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(1)

FORMULATION AND EVALUATION OF

DERMAL PATCHES OF GATIFLOXACIN

IN WOUND HEALING

THESIS

submitted to

The Tamilnadu Dr. M.G.R. Medical University, Chennai-600 032, India

As a partial fulfillment of the requirement for the Award of the Degree of

DOCTOR OF PHILOSOPHY

(Faculty of Pharmacy)

by

D. PRABU,

M.Pharm.,

Under the guidance of

Prof. Dr. C.B. THARANI,

M.D.,

Institute of Pharmacology

Madras Medical College

Chennai-600 003

India

(2)

Prof. Dr. C.B. Tharani, M.D.,

Professor and Head,

Department of Pharmacology, Saveetha Medical College, Thandalam, Chennai-602 105, India.

CERTIFICATE

This is to certify that the thesis entitled ‘FORMULATION AND

EVALUATION OF DERMAL PATCHES OF GATIFLOXACIN IN WOUND

HEALING’ is a bonafied thesis work of independent research carried out by Mr.

D.PRABU, M.Pharm., for the award of the degree of DOCTOR OF PHILOSOPHY

(Faculty of Pharmacy) under my supervision and guidance in the Institute of

Pharmacology, Madras Medical College, Chennai-3 and this thesis has not previously

formed the basis for the award of any degree, diploma, associateship, fellowship or

other similar title.

(3)

Prof. Dr. N. Narayanan, M.Pharm., Ph.D.,

Director - PG Studies, Jaya College of Pharmacy, Thiruninravur, Chennai-602 024, India.

CERTIFICATE

This is to certify that the thesis entitled ‘FORMULATION AND

EVALUATION OF DERMAL PATCHES OF GATIFLOXACIN IN WOUND

HEALING’ is a bonafied thesis work of independent research carried out by Mr.

D.PRABU, M.Pharm., for the award of the degree of DOCTOR OF PHILOSOPHY

(Faculty of Pharmacy) under my supervision and co-guidance in the Institute of

Pharmacology, Madras Medical College, Chennai-3 and this thesis has not previously

formed the basis for the award of any degree, diploma, associateship, fellowship or

other similar title.

(4)

DECLARATION

I hereby declare that the Ph.D., thesis entitled ‘FORMULATION AND

EVALUATION OF DERMAL PATCHES OF GATIFLOXACIN IN WOUND

HEALING’ submitted to Tamilnadu Dr.M.G.R. Medical University, Chennai-32,

is a record of independent work carried out by me in the Institute of

Pharmacology, Madras Medical College, Chennai under the supervision and

guidance of Prof. Dr. C.B. THARANI, M.D., and under the co-guideship of

Prof. Dr. N. NARAYANAN, M.Pharm., Ph.D.,. This thesis has not formed the

basis for the award of any degree, diploma, associateship, fellowship or other

similar title.

(5)

ACKNOWLEDGEMENT

I would like to express my sincere gratitude to respected Dean,

Dr. V. Kanagasabai, M.D., Madras Medical College, Chennai for providing the necessary requisites and facilities for my research work.

I take this opportunity with pride and immense pleasure in expressing my

deep sense of gratitude to my guide, Prof. Dr. C.B. Tharani, M.D., Professor

and Head, Department of Pharmacology, Saveetha Medical College, Chennai for

her critical, constructive, skillfull and innovative guidance.

I am extremely grateful for the patience and forbearance of my co-guide,

Prof. Dr. N. Narayanan, M.Pharm., Ph.D., Professor and Head, Department of Pharmaceutics, Jaya College of Pharmacy, Chennai, for helping me to complete

this thesis work by giving valuable suggestions and guidance. I am greatly

indebted to him for his parental affection, constant support, innovative ideas and

for bestowing the fruits of his vast experience over me for completing this work.

I express my gratefulness toDr. Nandhini., M.D.,Director and Professor, Institute of Pharmacology, Madras Medical College, Chennai, for sincere words

of encouragement and constant motivation throughout my research work.

I express my sincere gratitude to Prof. Dr. N. N. Rajendran, M.Pharm.,

Ph.D, Director of PG studies and Research, Swami Vivekananda College of

Pharmacy, Thiruchengode, for his valuable suggestions.

I extend my heartful thanks to Dr. M. Nappinnai, M.Pharm., Ph.D.,

Professor, Department of Pharmaceutics, Mohamed Sathak A.J. College of

Pharmacy, Chennai, for her valuable suggestions. Her support in so many ways

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I express my sincere gratitude to Dr. B. S. Lakshmi, M.Tech., Ph.D.,

Asst.Professor, Centre for Biotechnology, Anna University, Chennai, for her

constant encouragement and help.

I express my sincere thanks to Dr. Vijayalakshmi, M.D., D.C.P.,

Pathologist, Government Hospital, Royapettah, Chennai for helping me in

histopathological studies.

I am grateful to Mr. N. Venkatesan, Mr. D. Selvaraj, Mrs. N. Nalini,

and all other analyst of Anna University, Chennai.

I express my heartfelt thanks to all the teaching and non-teaching staff at

Institute of Pharmacology, Madras Medical College, Chennai, for their whole

hearted support during the period of my research work.

I am very much thankful to my friends Miss. U.M. Dhanalekshmi,

Mr. D. Anbalagan, Mr. B. Ponrasu, Mr. D. Babuand Mrs. B. Lakshmi Priya

for their moral support and sustained encouragement to help in all matters.

I wish to express my sincere thanks to Mr. Nagarajan, Students Xerox,

Chennai, who enabled me to bring this dissertation in to fine shape.

I express my love and soulful gratitude to my family for their keen support

and encouragement.

(7)

Dedicated to

My

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CONTENTS

Page No.

I

INTRODUCTION

1

1. Human skin 2

2. Functions of the skin 3

3. Wound 4

4. Categorization of wounds 4

5. Wound healing 6

6. Chronic wound healing 9

7. Infection as a challenge in wound healing 9

8. Potential wound pathogens 10

9. The microbial colonies 12

10. Antimicrobial agents-the role in wound management 13

11. Fluoroquinolones 14

12. Need for topical antimicrobial therapy 15

13. Ideal characteristics of wound dressing 17

14. Polymeric materials as wound dressing 17

15. Polysaccharide hydrogels 18

16. Selection of candidate drug 20

17. Selection of polymers 21

II

DRUG AND EXCIPIENTS PROFILE

22

1. Drug profile-Gatifloxacin 22

2. Excipients profile 25

III

AIM AND OBJECTIVES OF THE WORK

38

IV

REVIEW OF LITERATURE

40
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VI

MATERIALS AND METHODS

58

A. IDENTIFICATION OF GATIFLOXACIN 60

1. Solubility studies of Gatifloxacin

2. Fourier Transform Infrared (FT-IR) spectrum of

Gatifloxacin

3. Assay of Gatifloxacin

B. PREFORMULATION STUDIES 61

1. Gatifloxacin-polymer compatibility studies using

Fourier Transform Infrared (FT-IR) spectrum

2. Gatifloxacin-polymers compatibility studies using

Differential Scanning Calorimetry (DSC)

C. PREPARATION OF GATIFLOXACIN LOADED

DERMAL PATCHES 62

D. PRELIMINARY EVALUATION OF

GATIFLOXACIN LOADED DERMAL PATCHES 68

1. Fourier Transform Infrared (FT-IR) Spectroscopy

2. Differential Scanning Calorimetry (DSC)

3. Physical appearance

4. Surface pH

5. Folding endurance

6. Measurement of tensile strength of the dermal

patches

7. Measurement of swelling behavior

E. EVALUATION OF IN VITRO AND EX VIVO

PARAMETERS 70

1. Estimation of Gatifloxacin

2. Uniformity of Gatifloxacin content

3. Thickness measurement

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5. Percentage moisture absorption

6. Percentage moisture loss

7. Water vapour transmission rate (WVTR)

8. Contact angle measurement

9. SEM study

10. Microbial penetration study

11. Oxygen penetration measurement

12. Dispersion characteristics / wet integrity test

13. In vitro degradation test

14. In vitro Gatifloxacin release study 15. Bioadhesive strength measurements

16. Haemocompatibility study

16.1 Thrombus formation test

16.2 Haemolysis assay

F. EVALUATION OF CYTOCOMPATIBILTY AND

RESIDUAL GLUTARALDEHYDE CONTENT 80

1. Cytocompatibilty evaluation

2. Residual glutaraldehyde content

G. EVALUATION OF IN VITRO ANTIMICROBIAL

EFFICIENCY, IN VIVO AND STABILITY STUIDES 83

1. In vitro antimicrobial efficiency 2. In vivo studies

2.1 Primary skin irritancy test

2.2 Intracutaneous test

2.3 Systemic injection test

2.4 Wound healing evaluation

2.4.1 Biochemical analysis

2.4.1.1 Estimation of total protein

2.4.1.2 Estimation of total DNA

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2.4.1.4 Estimation of hexosamine

2.4.2 Histopathological studies

3. Stability studies

VII

RESULTS AND ANALYSIS

96

VIII

DISCUSSION

211

IX

SUMMARY AND CONCLUSION

221

X

BIBLIOGRAPHY

223
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ABBREVIATIONS

AO : amstrong

amu : atomic mass unit

C : degree Celsius

eV : electronvolt

% : percentage

ml : millilitre

l : microlitre

mM : millimole

g : grams

h : hours

mg : milligram

kg : kilogram

rpm : revolution per minute

min : minutes

mm Hg : millimetres of mercury

M : mole

mJ : millijoule

mm : millimetre

N : newton

nm : nanometre

sec : seconds

S.D : standard deviation

kPa : kilopascal

RH : relative humidity

Kv : kilovolt

g : microgram

MPa : megapascal

w/v : weight/volume

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1

Mankind has been covering wounds with a variety of materials to heals

them since times immemorial. Sumerian cuneiform tablets before 2000 BC

describe the application of poultices formed of mud, milk and plants to wounds

and Egyptian papyruses from 1550 BC to 1650 BC provide specific details of

how to wash the wound, prepare and apply plasters of honey, plant fibers, animal

fat and then bandage the wound1. Materials used to cover wounds since Egyptian

times have only slowly evolved from readily available materials in nature to

materials specifically designed by man to provide particular benefits for wound

healing. In the past quarter century, the evolution of wound dressing materials

has increased exponentially. The development and dissemination of later wound

treatments can be traced from the ancient Egyptians, via the Greeks to Roman

medicine, but the history of progress in wound care during the middle ages to the

present time is incomplete2. Although topical antimicrobial agents were utilised

in wound care for a long time during the 19thcentury the discovery of chemical

preservatives and disinfectants, as well as a better understanding of the nature of

infection and inflammation, allowed increased control of wound infection3.

In particular, the use of carbolic acid by Joseph Lister in operating theatres from

1865, significantly reduced mortality rates associated with surgical procedures.

Later, when it was accepted that micro organisms were the causative agents of

infections, it became possible to consider more specific targeting. Paul Ehrlich

began the search for chemicals with selective toxicity for infections, rather than

non-specific inhibitors, such as antiseptics and disinfectants4.

The discovery and development of antibiotics during the 20th century

provided potent antimicrobial agents with high specificity, which revolutionised

clinical therapy and marked the decline of many former remedies. However, the

relentless emergence of antibiotic resistant strains of pathogens, often with

multiple antibiotic resistance, together with the retarded discovery of novel

antibiotics has led to the need to find alternative treatments5. Faced with the

prospect of increased prevalence of antibiotic resistant pathogens and the

diminished effectiveness of current therapies, careful consideration of treatment

(15)

2

Future wound care products to promote wound healing are likely to be

sophisticated formulations that incorporate not only antimicrobial components,

but also designed to maintain a moist wound environment and optimise the

wound environment to promote healing. It was generally assumed by the health

care manufacturing community that this improvement in wound healing seen in

the acute wound would also be realized in the chronic wound. The first

semi-occlusive dressings for chronic wound management were introduced in the early

1980s6. The ideal wound dressing needs to ensure that the wound remains moist

with exudates, but not macerated and free of infection, while fulfilling

prerequisites concerning structure and biocompatibility7. Furthermore, they

should be non-cytotoxic and non-antigenic, guaranteed uniform cell distribution,

maintain cell viability, phenotype and should induce migration and proliferation

of epithelial cells, fibroblasts and endothelial cells, as well as the synthesis of

extracellular matrix components required for wound repair8. In addition, wound

dressings should exhibit ease of application, removal and proper adherence, in

order to ensure that there will be no areas of non-adherence left to create

fluid-filled pockets for bacterial proliferation9.

1.

Human skin

Skin, being the largest and highly complex organ in the human body is the

most affected organ in injuries. Skin is also known as the cutis or integument10

and has a surface area of 1.5-2 m2. It is well known and well understood that

skin provides thermal regulation, prevents dehydration through evaporative water

loss and acts as a barrier against chemical and infectious insult11.

The structure is composed of three layers, the stratified epithelium

(epidermis) separated from an underlying tissue stroma (dermis) by a well

characterized basement membrane (Fig. 1). There is a continuous process of

proliferation, maturation and death of cells in the epidermis, which is divided

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[image:16.595.105.504.134.358.2]

3

Fig. 1 The structure of human skin

The basement membrane is a dynamic structure of uniform thickness,

which is at the junction of the epidermis and underlying connective tissue.

Basement membrane stabilizes the epidermis mechanically by its

hemidesmosomal structure. The dermal matrix, which provides considerable

strength to skin by virtue of the arrangement of collagen fibers has specialized

components and structures. Collagenous mesh work, is interwoven with varying

contents of elastin fibers, proteoglycons (GAG being predominantly hyaluronic

acid and dermatan sulfate with some chondroitin-6-sulphate and heparin

sulphate), fibronectin and other components. In dermis, blood vessels, lymphatic

vessels, nerves, sebaceous and sweat glands and hair follicles are also present12.

2.

Functions of the skin

13

Containment of body fluids and tissues

Protection from harmful external stimuli

Barrier function

Microbial barrier

(17)

4 Radiation barrier

Thermal barrier

Electrical barrier

Reception of external stimuli

Tactile (Pressure)

Pain

Thermal

Regulation of body temperature

Synthesis and metabolism

Disposal of biochemical waste

Interspecies identification

Blood pressure regulation

3.

Wound

The wound has been defined as a disruption of normal anatomical

structure of a cell and more importantly, the function14. There are four basic

responses that can occur following an injury. Normal repair is the response

where there is a re-established equilibrium between scar formation and scar

remodeling. This is the typical response, which most humans experience

following injury. The pathological response to tissue injury stands in sharp

contrast to the normal repair response. In excessive healing there is too much

deposition of connective tissue that results in altered structure and thus loss of

function15.

4.

Categorization of wounds

Based on the nature of the repair process, wounds can be classified as

Acute wound

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5

4.1 Acute wound

Acute wounds are usually tissue injuries that heal completely, with

minimal scarring, within the expected time frame, usually 8-12 weeks16. The

primary causes of acute wounds include mechanical injuries due to external

factors such as abrasions and tears which are caused by frictional contact

between the skin and hard surfaces. Mechanical injuries also include penetrating

wounds caused by knives and gun shots and surgical wounds caused by surgical

incisions. Another category of acute wounds include burns and chemical injuries,

which arise from a variety of sources such as radiation, electricity, corrosive

chemicals and thermal sources. The temperature of the source and the exposure

time influence the degree of a thermal burn17. Burns will normally require

specialised care because of the associated trauma.

4.2 Chronic wound

Chronic wounds on the other hand arise from tissue injuries that heal

slowly and not healed beyond 12 weeks and often reoccur18. Such wounds fail to

heal due to repeated tissue insults or underlying physiological conditions such as

diabetes and malignancies, persistent infections, poor primary treatment and

other patient related factors19. This results in a disruption of the orderly sequence

of events during the wound healing process. Chronic wounds include decubitus

ulcers (bedsores) and leg ulcers (venous, ischaemic or traumatic origin).

Based on the number of skin layers affected can be classified as

Partial thickness wound

Full thickness wound

4.3 Partial thickness wound

Injury that affects the epidermal skin surface alone is referred to as a

(19)

6

dermal layers, including the blood vessels, sweat glands and hair follicles is

referred to as partial thickness wound20.

4.4 Full thickness wound

Full thickness wounds occur when the underlying subcutaneous fat or

deeper tissues are damaged in addition to the epidermis and dermal layers21.

Wounds both acute and chronic that is difficult to heal are known as ‘complex

wounds’ with unique characteristics22. The properties of complex wounds from

their review can be summarised as extensive loss of the integument which

comprises skin, hair and associated glands, infection which may result in tissue

loss, tissue death or signs of circulation impairment and presence of pathological

conditions.

5.

Wound healing

Wound healing is the complex and dynamic process that results in the

restoration of anatomical continuity and function (Fig.2). Wound healing

progresses through a series of interdependent and overlapping stages in which a

variety of cellular and matrix components act together to reestablish the integrity

of damaged tissue and replacement of lost tissue23, 24. Wounds caused by trauma

or through surgery generally follow a well-defined wound healing process that

involves four main stages:

Haemostasis

Inflammation

Migration

Maturation

These stages overlap and the entire process can last for months. During

the coagulation phase after injury, platelets initiate the wound healing process by

releasing a number of soluble mediators, including platelet-derived growth factor

(20)

7

fibroblast growth factor (FGF) and transforming growth factor-b (TGF-b). These

rapidly diffuse from the wound and inflammatory cells are drawn to the area of

the injury. In general, growth factors are mitogens that stimulate proliferation of

wound cells (epithelial cells, fibroblasts, and vascular endothelial cells). Most

growth factors are also able to stimulate directed migration of target cells

(chemotaxis) and regulate differentiated functions of wound cells, such as

expression of extracellular matrix (ECM) proteins25, 26.

5.1 Haemostasis

Bleeding usually occurs when the skin is injured and serves to flush out

bacteria or antigens from the wound. In addition, bleeding activates haemostasis

which is initiated by exudate components such as clotting factors. Fibrinogen in

the exudate elicits the clotting mechanism resulting in coagulation of the

exudates (blood without cells and platelets) and, together with the formation of a

fibrin network, produces a clot in the wound, causing bleeding to stop. The clot

dries to form a scab to provide strength and support to the injured tissue.

Haemostasis therefore, plays a protective role as well as contributing to

successful wound healing27.

5.2 Inflammation

The inflammatory phase occurs almost simultaneously with haemostasis,

sometimes from within a few minutes of injury to 24 h and lasts for about 3 days.

It involves both cellular and vascular responses. The release of protein rich

exudates into the wound causes vasodilatation through release of histamine and

serotonin, allows phagocytes to enter the wound and engulf dead cells (necrotic

tissue). Platelets liberated from damaged blood vessels become activated as they

come into contact with mature collagen and form aggregates as part of the

(21)
[image:21.595.99.514.128.456.2]

8

Fig. 2 Phases of wound healing

(i) Haemostasis phase (ii) Inflammatory phase

(iii) Migratory phase (iv) Maturatory phase

5.3 Migration

The migration phase involves the movement of epithelial cells and

fibroblasts to the injured area to replace damaged and lost tissue. These cells

regenerate from the margins, rapidly growing over the wound under the dried

scab (clot) accompanied by epithelial thickening. The proliferative phase occurs

almost simultaneously or just after the migration phase (day 3 onwards) and

basal cell proliferation, which lasts between 2 and 3 days. Granulation tissue is

formed by the in-growth of capillaries and lymphatic vessels into the wound and

collagen is synthesised by fibroblasts giving the skin strength and form. By the

fifth day, maximum formation of blood vessels and granulation tissue has

(22)

9

wound. The fibroblast proliferation and collagen synthesis continues upto two

weeks28.

5.4 Maturation

Maturation phase (remodeling phase) involves the formation of cellular

connective tissue and strengthening of the new epithelium which determines the

nature of the final scar. Cellular granular tissue is changed to a cellular mass

from several months up to about 2 years29.

6.

Chronic wound healing

Chronic or non healing ulcers are characterized by defective remodeling

of the extracellular matrix, a failure to re-epithelialize and prolonged

inflammation30. The epidermis fails to migrate across the wound tissue and there

is hyper-proliferation at the wound margins that interferes with normal cellular

migration over the wound bed, probably through inhibition of apoptosis within

the fibroblast and keratinocyte cell populations. Fibroblasts obtained from

chronic ulcers show a decreased response to exogenous application of growth

factors such as PGDF-b and TGF-b31. In chronic wounds, cells accumulate that

are unresponsive to wound healing signals, therefore topical application of

growth factors is unlikely to lead to wound closure until adjacent cells that are

capable of responding to growth factors migrate into the wound32.

7.

Infection as a challenge in wound healing

Infection is the main cause of delayed healing in primarily closed

(surgical) wounds, traumatic and burn wounds and chronic skin ulcers. The

recognition of a surgical site infection (SSI) is relatively easy when an incised

wound presents with an extended, raised inflammatory margin (cellulitis) around

the wound, sometimes associated with lymphangitis, raised local or systemic

(23)

10

The nature of combat injuries is such that bacterial contamination is

frequently present in traumatic wounds. One of the natural purposes of free and

unimpeded bleeding from wounds is to flush out potentially contaminating

microorganisms that may have gained entry to the wound from the environment.

The quantitative tissue bacterial levels exceeding 105 bacteria per gram of wound

tissue have a deleterious effect on healing in acute traumatic and surgical

wounds, chronic wounds, and skin grafts35. The inappropriate and uncoordinated

inflammatory response relates to invasion of microorganisms through the

normally intact resistant skin barrier. The bacteria release toxins and proteases,

depending on their pathogenicity, which facilitates their spread. The host

response, locally and systemically may be overwhelmed, particularly in

immunosuppressed patients, leading to bacteraemia, systemic inflammatory

response syndrome, sepsis, organ failure or death36. Infection may also be

contained, as suppuration, or completely resolved depending on host response,

bacterial load and virulence.

8.

Potential wound pathogens

The majority of micro-organisms is less than 0.1 mm in diameter and can

therefore only be seen under a microscope. They can be categorised into different

groups, such as bacteria, fungi, protozoa and viruses, depending on their

structure and metabolic capabilities37(Table 1).

8.1 Bacteria

These are relatively simple cells, that can be further categorized based on

the differences in their shape and cell wall structure. Cocci (spherical shaped cells), Bacilli (rods) andSprirochaetes (spirals) can be arranged singly; however

Cocci and Bacilli can also be found in pairs, chains and irregular clusters. They can be visualised using a bacteriological staining process called Gram staining;

after Gram staining, Gram-positive bacteria are purple and Gram-negative

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11

Clostridia, require specialised stains. The growth and survival of all bacteria is dependent upon environmental factors, for example strict aerobes require oxygen

whereas anaerobes are rapidly killed by oxygen. It is important to note, however,

that both aerobes and anaerobes can survive in close proximity to each other and

that some can survive in both conditions by growing aerobically and then

switching to anaerobic metabolism in the absence of oxygen, these are known as

facultative anaerobes.

Table 1. The potential wound pathogens

Sl.No. Types Micro-organisms

1 Gram-positive cocci

Streptococcus pyogenes Staphylococcus aureus Enterococcus faecalis

2 Gram-negative aerobic rods Pseudomonas aeruginosa

3 Gram-negative facultative rods

Enterobacterspecies

Escherichia coli Klebsiellaspecies

Proteusspecies

4 Anaerobes Bacteroides

Clostridium

5 Fungi Yeasts (Candida)

Aspergillus

The microbes Staphylococcus aureus, Streptococcus pyogenes,

Corynebacterium spp., Escherichia coli and Pseudomonas aeruginosaare some

important organisms causing wound infection. Among the most common

micro-organisms that cause wound infection are Staphylococcus aureus and

-hemolytic Streptococcus, which are considered “transient flora” of the skin.

Infected wounds heal more slowly and have an increased incidence of scarring.

(25)

12

8.2 Fungus

These are composed of larger, more complex cells than bacteria. They are

either single-celled yeasts or multi-cellular organisms with a nuclei contained

within a cell membrane. Fungus can be responsible for superficial infections of

the skin, nails and hair. Although they have been isolated from wounds, they are

rarely pathogenic in this setting41.

8.3 Protozoa

These are single celled organisms within a fragile membrane and without

a cell wall. They are most significantly associated with infected skin ulcers.

8.4 Viruses

These are composed of genetic material (nucleic acid) enclosed within a

protein coat or a membranous envelope. Although viruses do not generally cause

wound infections, bacteria can infect skin lesions formed during the course of

certain viral diseases. It is important to remember that different micro-organisms

can exist in polymicrobial communities and this is often the case within the

margins of a wound42.

9.

The microbial colonies

The bacterial colonies may induce scarring, resulting in wound bursting,

reduction of oxygen tension and destruction of existing tissue matrix. Still, less

attention has been given to the contribution of dressings capable of controlling

the clinical outcome43, 44. Contaminated or colonized wounds should heal after

adequate perfusion is established, non-viable tissue is removed, a moist

environment is maintained and exudate controlled. Routine piston syringe

irrigation with saline is sufficient for wound cleansing. Antiseptics or

disinfectants (Povidone iodine, chlorhexidine, alcohol, acetic acid, sodium

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13

care. However, their use is indicated in difficult-to-treat wounds. Critical

colonization indicates a situation in which the bacterial balance exceeds the

ability of host defenses to clear the bacterial biofilm and normal healing is

impeded. Comprehensive wound care must include cleansing, debridement and

exudate management. A topical antimicrobial to decrease bioburden should be

added to a wound that fails to heal or continues to produce exudates despite the

comprehensive care.

10.

Antimicrobial agents - the role in wound management

Quality of care is a critical requirement for wound healing. Strategies that

optimise the tissue repair process have evolved with advances in understanding

of the wound healing process45. Although the type of open wound management

must be individualised for each wound, cleansing bacteria, soil and other debris

from traumatic wounds, as well as surgical debridement cannot be over

emphasised. Debridement removes tissue heavily contaminated by soil

infection-potentiating fractions and bacteria and excises devitalised tissues that impair the

wound’s ability to resist infection46.

10.1 Topical wound cleansers

The skin and wound cleansers are designed as topical solutions with

varying degrees of antimicrobial activity, wound cleansers may also be

antimitotic and adversely affect normal tissue repair and cleansers are most toxic

to fibroblasts. The effects of antiseptic treatment on fibroblasts are more

encompassing than just toxicity47. Keratinocyte monolayers, representing the in vivo basal layer of the epidermis that epithelialises the wound surface after injury, are more sensitive to wound cleansers such as hydrogen peroxide and

(27)

14

10.2 Topical wound antiseptics

Repeated and excessive treatment of wounds with antiseptics without

proper indications may have negative outcomes or promote a microenvironment

similar to those found in chronic wounds. However, when applied at the proper

times and concentrations, some classes of antiseptics may provide a tool for the

clinician to drive the wound bed in desired directions. Wound management

strategies address the delicate balance between cytotoxicity and cellular

activities. Irritation of intact healthy tissue could seriously impact the rate and

quality of tissue repair. Although the removal of antiseptics from the wound bed

management arsenal cannot be advocated, care should be used when

administering these products47. Despite cytotoxicity data, most antiseptics have

not been shown to clearly impede healing, especially newer formulations like

cadexomer iodine (rapid healing) and novel silver delivery systems. These

compounds appear to be relatively safe and efficient in preventing infection in

human wounds48.

10.3 Topical wound antibiotics

Antibiotics are now generally accepted that they are essential for the

management of clinically infected wounds, the choice of antibiotic to be used is

not always apparent49. Only after a comprehensive assessment process including

consideration of patient characteristics, the results of microbiological

investigations and the identification of both the nature and location of the wound,

the most appropriate antibiotic can be identified. Resistance to antibiotics has

become a serious problem in recent years particularly with the rise of epidemic

strains of methicillin resistant Staphylococcus aureus. The overuse of

broad-spectrum antibiotics will only serve to exacerbate the situation.

11.

Fluoroquinolones

As there is an increase in antimicrobial resistance, strategies for the

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15

with infectious diseases including those of skin and skin structures.

Fluoroquinolones are an important class of antimicrobial agents that are useful

for the treatment of patients with skin and skin structure infections. The

fluoroquinolones are an unique class of antibiotics with a broad spectrum of

activity against Gram-positive and Gram-negative aerobes and anaerobes50. The

fluoroquinolones are suitable for treating skin infections, both uncomplicated and

complicated, due to their broad spectrum and rapid bactericidal activity.

The fluoroquinolones are many and varied in their structure, activity and

pharmacology. Agents available throughout the world include Amifloxacin,

Ciprofloxacin, Cinoxacin, Enoxacin, Fleroxacin, Gatifloxacin, Gemifloxacin,

Grepafloxacin, Levofloxacin, Lomefloxacin, Moxifloxacin, Nalidixic acid,

Nitroxoline, Norfloxacin, Ofloxacin, Pefloxacin, Rufloxacin, Sparfloxacin,

Temafloxacin, Tosufloxacin and Trovafloxacin. The fluoroquinolones offer

several advantages over Penicillin and Cephalosporin -Lactums and Macrolides.

The newer agents, Levofloxacin, Gatifloxacin and Moxifloxacin are all

administrered once-daily, which may improve patient compliance. Their broad

spectrum activity and the agents for the management of skin infections must be

considered carefuly in a societal context. Diabetic foot infections, surgical

wounds and other infections with uncertain bacterial aetiology or polymicrobic

causes are situations in which fluoroquinolones may offer the most advantages

over other antibiotics. Their excellent tissue penetration, rapid bactericidal

activity and oral dosage form may reduce the necessity or length of

hospitalization51.

12.

Need for topical antimicrobial therapy

Systemic antimicrobials are administered when local measures fail to

control chronic wound infection. Continued topical antimicrobial therapy is

advised as systemic antimicrobials do not reach therapeutic levels in the

relatively a vascular infected wound tissue52. Topical antimicrobial agents are

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16

treatment of primary and secondary pyodermas. The ideal topical agent should

have a broad spectrum of activity against common skin pathogens. Traditionally,

the injured area should be covered with antimicrobial cream once or twice each

day. However, the patients frequently suffer from a considerable amount of

discomfort with the application of such topical drugs in the form of cream.

Furthermore, a substantial nursing effort is required for the replacement of

wound dressings. Recently, wound dressings or artificial skin containing

antibiotics have been developed for the inhibition of wound infection. The

delivery of antimicrobial agents to local wound sites may be a preferred option to

systematic administration for several reasons. Antimicrobial doses needed to

achieve sufficient systemic efficiency often results in toxic reactions such as the

cumulative cell and organ toxicity53.

The use of dressing to deliver antibiotic to wound sites can provide tissue

compatibility, low occurrence of bacterial resistance and reduced interference

with wound healing. The use of lower antimicrobial doses within the dressings

also reduced the risk of systemic toxicity in a considerable amount. In addition,

local delivery from dressings can overcome the problem of ineffective systemic

antimicrobial therapy resulting from poor blood circulation at the extremities in

diabetic foot ulcer. These devices incorporate antibiotics in the wound dressing

together with hydrogel film artificial skin. Wound infection can be decreased

with the treatment of wound dressings that incorporate antimicrobials. The

laborious replacement of wound dressings and the damage inflicted on the newly

formed epithelium can be avoided. Recently, dressings that contain and release

antimicrobial agents at the wound surface have entered the marketplace. These

dressings usually provide a continuous or sustained release of the antimicrobial

agent at the wound surface to provide a long-lasting antimicrobial action in

combination with maintenance of physiologically moist environment for healing.

In the present study, the objective is to develop a hydrogel wound dressing that

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17

13.

Ideal characteristics of wound dressing

Sterile and non-toxic

To adsorb wound odour

To immobilize the wound

To provide thermal insulation

To remove drainage and debris

Non-allergenic and non-sensitizing

To promote physical patient comfort

To promote tissue recontraction process

Free from particulate and toxic products

Able to protect the wound from secondary infection

To provide a moisturized wound healing environment

To protect the wound and new tissue growth from mechanical injury.

14.

Polymeric materials as wound dressing

There are a handful of advanced wound dressings that are composed of

biological materials as opposed to synthetic polymers. These biomaterials are

typically extracellular matrix components and are designed to have an impact in

the local wound environment beyond moisture management. A variety of carriers

have been explored to modify the response to drugs that are delivered topically to

the wound. These include gels, nanoparticles, polymer matrices, liposomes and

the dermal film system54. Provision of a matrix to sustain drug release in the

wound can be achieved in several ways. One of them is hydrogel membrane and

can serve as a drug reservoir. It appears to be extremely effective way of

maintaining a therapeutic concentration of drug on the surface for considerable

periods of time. In addition, the ability of hydrogel to release an entrapped drug

into aqueous medium and to regulate the release of drug by control of swelling

and cross-linking makes them particularly suitable for controlled release

applications. Hydrogels can be applied for the release of both hydrophilic and

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18

Hydrogels are three dimensional, hydrophilic cross-linked, polymeric

networks that have capacity to swell by absorbing water or biological fluids.

Hydrogels can be synthesized by using hydrophilic monomers, polymers or

copolymers, depending on the type of the monomers or polymers or the

composition of the copolymers. Their hydrophilicity and their swelling capacity

as a result of hydrophilicity may differ. The cross-linking ratio is one of the most

important factors that affect the swelling of hydrogels56. Hydrogels are ideal

biopolymeric pharmaceutical forms for the treatment of skin wounds. They have

low interfacial tension, high molecular and oxygen permeability, good

moisturizing and mechanical properties that resemble physiological soft tissue57.

For this reasons, polysaccharides are having hydrogel forming properties have

been considered to be advantageous in its application as a wound dressing

material58. Since then, the use of dressings that keep wound tissues moist has

been associated with increased healing rates, improved cosmesis, reduced pain,

reduced infection and reduced overall health care costs59.

From a realistic point of view, the need of the h is not only an ideal skin

substitute, but also an affordable one. In other words, the product price should

not exaggerate expenses incurred by hospital stay and related medical care. At an

experimental level different approaches have generated a vast score of products

showing promise for wound healing.Among the numerous polymers that have

been proposed for the preparation of hydrogels. Polysaccharides have a number

of advantages over the synthetic polymers which were initially employed in the

field of Pharmacy. The synthetic polymers have certain disadvantages such as

high cost, toxicity, environmental pollution during synthesis, non-renewable

sources, side effects and poor patient compliance60.

15.

Polysaccharide hydrogels

In recent years, a number of studies have greatly contributed to our

present understanding of polysaccharidic hydrogel networks, with numerous

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19

versatility in modified drug delivery, more recent progresses have been made in

the use of hydrogels as matrices for the encapsulation of living cells, as

biologically friendly scaffolds for tissue engineering and for the controlled

release of antimicrobials. For these purposes, polysaccharides have been widely

used to prepare wound healing materials (Table 2).

Table 2. Classification of polysaccharides

1. Natural polysaccharides Marine origin/algae polysaccharides Plant polysaccharides Animal polysaccharides Microbial Polysaccharides Agar Laminarin Alginic acid Carrageenans (1) Shrubs/tree exudates Gum arabica Gum ghatti Gum karaya Khaya gum Albizia gum Gum tragacanth Chitin Chitosan Chondroitin sulfate Hyaluronic acid Dextran Curdian Pullulan Zanflo Emulsan Krestin Gellan gum Scleroglucan Xanthan gum

Baker’s yeast glycan Schizophyllan Lentinan (2)Seed gums

Guar gum Starch

Locust bean gum Amylase cellulose (3)Extracts

Pectin Larch gum (4) Tuber and roots

Potato starch

2. Semi synthetics polysaccharides

Starch derivatives Cellulose derivatives

Heta starch Starch acetate Starch phosphates

Methyl Cellulose (MC)

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20

Indeed, polysaccharides are abundant and readily available from

renewable sources such as the algae and plant kingdoms, cultures of microbial

selected strains, as well as through recombinant deoxyribonucleic acid (DNA)

techniques61. Thus, they have a large variety of composition and properties that

cannot be easily mimicked in a chemical laboratory and the ease of their

production makes numerous polysaccharides cheaper than synthetic polymers.

Advantage of polysaccharides

Biodegradable

High biocompatibility

Non-toxicity, low cost

Environmental friendly processing

Local availability

Better patient tolerance as well as public acceptance

Disadvantage of polysaccharides

Easy microbial contamination and uncontrolled rate of hydration

Batch to batch variation

However, this can be prevented by proper handling and the use of

preservatives.

16.

Selection of candidate drug

The choice of drug for dermal delivery should be done after giving careful

consideration.

The drug should not produce any allergic response or cutaneous

irritation.

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21

Oral administration leads to side effects. So, the local delivery of the

drug by topical administration may enable the maintenance of a high

local antimicrobial concentration for an extended duration of release

without causing systemic toxicity. Based on the above mentioned

reasons, Gatifloxacin is considered to be a potential drug candidate for

topical wound dressing.

17. Selection of polymers

The polymers were selected depending upon their solubility, their film

forming capacity, biocompatibility and their non-interference in the estimation

procedure. In the present study, chitosan, sodium alginate, xanthan gum, gellan

gum, hydroxypropyl methylcellulose (HPMC) and hydroxypropyl cellulose

(HPC) were selected. Since, they exhibited required film characters as compared

(35)
(36)

22

1. DRUG PROFILE

Name :Gatifloxacin62-66

Chemical name :1-cyclopropyl-6-fluoro-1,4-dihydro-8-methoxy-7-(3-methyl piperazin-1-yl)-4-oxo-quinoline-3-carboxylic acid.

Chemical structure

Empirical formula : C19H22FN3O4 Molecular weight :375.39

Melting point :182-185°C

Functional category : Antimicrobial agent

Description

It is a white to light yellow crystalline powder and odourless.

Solubility

Solubility of Gatifloxacin is pH dependent, with maximum aqueous

solubility (40 to 60 mg/ml) occurring in a pH range of 2 to 5.

Pharmacokinetic properties

Absorption

Gatifloxacin is well absorbed from the gastrointestinal tract after oral

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23

bioavailability of Gatifloxacin is 96 %. Peak plasma concentration of

Gatifloxacin usually occur 1-2 h after oral dosing. The mean steady-state peak

and trough plasma concentrations attained following a dosing regimen of 400 mg

once daily are approximately 4.2 µg/ml and 0.4 µg/ml, respectively, for oral

administration.

Distribution

Serum protein binding is approximately 20 % in volunteers and is

concentration independent. The mean volume of distribution at steady-state

(Vdss) ranged from 1.5 to 2.0 L/kg. Gatifloxacin is widely distributed throughout

the body into many body tissues and fluids. Rapid distribution of Gatifloxacin

into tissues results in higher Gatifloxacin concentrations in most target tissues

than in serum.

Metabolism

Gatifloxacin undergoes limited biotransformation in humans with less

than 1 % of the dose excreted in the urine as ethylenediamine and

methylethylenediamine metabolites. Human studies indicate that Gatifloxacin is

not an enzyme inducer; therefore, Gatifloxacin is unlikely to alter the metabolic

elimination of itself or other co-administered drugs.

Excretion

Gatifloxacin is excreted as unchanged drug primarily by the kidney. More

than 70 % of an administered Gatifloxacin dose was recovered as unchanged in

the urine within 48 h following oral and intravenous administration and 5 % was

recovered in the feces. The mean elimination half-life of Gatifloxacin ranges

from 7 to 14 h and is independent of dose and route of administration. Renal

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24

Mechanism of action

Bactericidal action of Gatifloxacin depends on blocking of bacterial

Deoxyribonucleic acid (DNA) replication by binding itself to an enzyme called

DNA gyrase, which allows the untwisting required to replicate one DNA double

helix into two. Notably the drug has 100 times higher affinity for bacterial DNA

gyrase than for mammalian. It is active against both Gram-positive and

Gram-negative bacteria. It should be used only to treat or prevent infections that

are proven or strongly suspected to be caused by bacteria. The bactericidal action

of Gatifloxacin results from inhibition of the enzymes topoisomerase II

(DNA gyrase) and topoisomerase IV, which are required for bacterial DNA

replication, transcription, repair and recombination.

Drug interactions

No P450 interactions have been observed with Gatifloxacin.

Co-administration with multivalent cations significantly decreases Gatifloxacin

absorbance from the gut.

Adverse drug reactions

Gatifloxacin is generally well tolerated, with most common side effects

like dizziness, headache, nausea, diarrhoea, hepatic damage, hypoglycemia,

arthropathies and tendonitis.

Therapeutic indications

For the treatment of bronchitis, sinusitis, community-acquired pneumonia

and skin infections (abscess and wounds).

Dosage and administration

Eye drops - 0.3% w/v eye drops.

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25

Injections - Gatifloxacin intravenous injection is available in 40 ml (400 mg)

single use vials as a sterile, preservative-free aqueous solution.

2. EXCIPIENTS PROFILE

2.1 Chitosan67

Synonyms

Deacetylated chitin, deactylchitins, poly - D -glucosamine, poly- (1,4 -

- glucopyranosamine).

Chemical name : Poly- (1, 4) -2- amino -2- deoxy-D-glucose.

Structural formula

Empirical formula : (C6H11O4N)· n Molecular weight :10000-1000000

pH :4-6

Density :1.35-1.4 g/cm2

Description

Chitosan is natural high molecular polysaccharide extracted from the sea

shrimp and crab shell, as food additive and raw material for pharmacy. It is

white powder, harmful, odourless, pollutive, corrosive,

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26

Solubility

Sparingly soluble in water, practically insoluble in ethanol (95 %), other

organic solvents, and neutral or alkali solutions at pH above approximately 6.5.

Chitosan dissolves readily in dilute and concentrated solutions of most organic

acids and to some extent in mineral inorganic acid.

Functional category

Coating agent, disintegrant, film forming agent, mucoadhesive, tablet

binder and thickening agent.

Applications in pharmaceutical formulation

Chitosan is used in cosmetics and is under investigation for use in a

number of pharmaceutical formulations. The suitability and performance of

chitosan as a component of pharmaceutical formulations for drug delivery

applications has been investigated in numerous studies. These include controlled

drug delivery applications, use as a component of mucoadhesive dosage forms,

rapid release dosage forms, improved peptide delivery, colonic drug delivery

systems and use for gene delivery. Chitosan has been processed into several

pharmaceutical forms including gels, films, beads, microspheres, tablets and

coating for liposomes.

Incompatibilities

Chitosan is incompatible with strong oxidizing agents.

2.2 Sodium alginate67

Synonyms

Algin, alginic acid, E401, Kelcosol, Keltone, Protanal and sodium

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27

Chemical name

6-(2-carboxy-4,5-dihydroxy-6-methoxyoxan-3-yl)oxy-4,5-dihydroxy-3

methoxyoxane -2 carboxylic acid.

Structural formula

Empirical formula : (C6H7NaO6)n Molecular weight : 10000-600000

pH : 7.2 for a 1% w/v aqueous solution

Density : 1.601 g/cm3

Description

Sodium alginate occurs as an odorless and tasteless, white to pale

yellowish brown colored powder.

Solubility

Practically insoluble in ethanol (95%), ether, choloform, and ethanol/

water mixtures in which the ethanol content is greater than 30 %. Also,

practically insoluble in other organic solvents and aqueous acidic solutions in

which the pH is less than 3. Slowly soluble in water, forming a viscous colloidal

solution.

Functional category

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28

Applications in pharmaceutical formulation

Sodium alginate is used in a variety of oral and topical pharmaceutical

formulations. In tablet formulations, sodium alginate may be used as both a

binder and disintegrant and it has been used as diluents in capsule formulations.

Sodium alginate has also been used in the preparation of sustained release oral

formulations since it can delay the dissolution of a drug from tablets, capsules

and aqueous suspensions. In topical formulations, sodium alginate is widely used

as a thickening and suspending agent in a variety of pastes, creams, gels and as a

stabilizing agent for oil in water emulsions. Therapeutically, sodium alginate has

been used in a hemostatic agent in surgical dressings. Alginate dressings, used to

treat exuding wounds, often contain significant amounts of sodium alginate as

this improves the gelling properties. Sponges composed of sodium alginate and

chitosan produce a sustained drug release and may be useful as wound dressings

or as tissue engineering matrices.

Incompatibilities

Sodium alginate is incompatible with acridine derivatives, crystal violet,

phenyl mercuric acetate, phenyl mercuric nitrate, calcium salts, heavy metals and

ethanol.

2.3 Xanthan gum67

Synonyms

Corn sugar gum; E415; Keltrol; polysaccharide B-1459; Vanzan NF;

Xantural.

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29

Structural formula

Empirical formula : (C35H49O29)n

Molecular weight : Approximately 2 x 106

pH : 6.0 - 8.0 for a 1 % w/v aqueous solution.

Bulk density : 1.5 g/cm3

Description

Xanthan gum occurs as a cream or white colored, odorless, free flowing

and fine powder.

Solubility

Practically insoluble in ethanol and ether; soluble in cold or warm water.

Functional category

Stabilizing agent, suspending agent and thickening agent.

Applications in pharmaceutical formulation

Xanthan gum is widely used in oral and topical pharmaceutical

formulations, cosmetics, and foods as a suspending and stabilizing agent. It is

also used as a thickening, suspending agent and emulsifying agent. xanthan gum

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30

been incorporated in an ophthalmic liquid dosage form, which interacts with

mucin, thereby helping in the prolonged retention of the dosage form in the

precorneal area. Xanthan gum can be used to increase the bio adhesive strength

in vaginal formulations and as a binder in colon specific drug delivery systems.

Xanthan gum is also used a hydrocolloid in the food industry, and in cosmetics

and it has been used as a thickening agent in shampoo.

Incompatibilities

Xanthan gum is an anionic material and is not usually compatible with

cationic surfactants, polymers or preservatives as precipitation occurs.

2.4 Gellan gum68,69

Synonyms

E418, Gellan, K9A-40, Gelrite, FG2250, Gelrite(R), Gellan gum, Gelrite

(TM).

Structural formula

Molecular weight : Approximately 500,000

pH : 3.5-10

Bulk density : Approximately 836 kg/m3

Description

Off white powder of exocellular hetero polysaccharide produced by

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31

Solubility

Soluble in water, insoluble in ethanol.

Functional category

Stabilizing agent, suspending agent, tablet and capsule disintegrant, tablet

binder and thickening agent.

Applications in pharmaceutical formulation

Gellan gum is used in a variety of oral and topical pharmaceutical

formulations. In tablet formulations, gellan gum may be used as both a binder

and disintegrant and it has been used as a diluent in capsule formulations. gellan

gum has also been used in the preparation of sustained release oral formulations

since it can delay the dissolution of a drug from tablets, capsules and aqueous

suspensions. In topical formulations, gellan gum is widely used as a thickening

and suspending agent in a variety of pastes, creams, gels and as a stabilizing

agent for oil in water emulsions. It has been used in the formulation of

nanoparticles. The adhesiveness of hydrogels prepared from gellan gum has been

investigated and drug releases from oral mucosal adhesive tablets and buccal

gels, based on gellan gum have been reported.

Incompatibilities

Gellan gum is an anionic material and is not usually compatible with

cationic surfactants, polymers or a preservative as precipitation occurs.

2.5 Hydroxypropyl methylcellulose67

Synonym

Benecel, hydroxypropyl methylcellulose, HPMC, hypromellosum,

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32

Chemical name

2[6[4,5bis(2hydroxypropoxy)2(2hydroxypropoxymethyl)6methoxyoxan3yl]oxy4,5dimethoxy2(methoxymethyl)oxan3yl] oxy 6

-(hydroxymethyl)-5 methoxyoxane-3,4-diol.

Structural formula

Empirical formula : C32H60O19 Molecular weight : 748.80 g/mol

pH : 5-8 (2 % w/w solution)

Bulk density : 0.341 g/cm3

Description

Hydroxypropylmethylcellulose is an odorless and tasteless, white or

creamy-white fibrous or granular powder.

Solubility

Soluble in cold water, practically insoluble in hot water, chloroform,

ethanol (95 %) and ether, but soluble in mixtures of ethanol and

dichloromethane, mixtures of methanol and dichloromethane and mixtures of

water and alcohol.

Functional category

Bioadhesive material, coating agent, controlled release agent, emulsifying

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33

solubilizing agent, suspending agent, sustained release agent, tablet binder and

thickening agent.

Applications in pharmaceutical formulations

Hydroxypropyl methylcellulose is widely used in oral, ophthalmic, nasal,

and topical pharmaceutical formulations. Hydroxypropyl methylcellulose used as

a thickening agent to vehicles for eye drops and artificial tear solutions.

Incompatibilities

It is incompatible with some oxidizing agents. Since it is non-ionic,

hydroxypropyl methylcellulose will not complex with metallic salts or ionic

organics to form insoluble precipitates.

2.6 Hydroxypropyl Cellulose67

Synonyms

Cellulose, hydroxypropyl ether, E463, hyprolose, Klucel, Methocel,

Nisso HPC, oxypropylated cellulose.

Chemical name : 2-hydroxypropyl ether

Structural formula

Empirical formula :C36H70O19 Molecular weight :100 g/mol

pH : 5.0 - 8.5

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34

Description

Slightly hygroscopic, white or off-white, almost odourless, granular or

fibrous powder.

Solubility

Hydroxypropyl cellulose is freely soluble in water below 38°C, forming a

smooth, clear,colloidal solution. In hot water, it is insoluble and is precipitated

as a highly swollen floc at a temperature between 40 and 45°C. Hydroxypropyl

cellulose is soluble in many cold or hot polar organic solvents such a dimethyl

formamide, dimethyl sulfoxide, dioxane, ethanol (95 %), methanol, propan-2-ol

(95 %) and propylene glycol. Practically insoluble in aliphatic hydrocarbons;

aromatic hydrocarbons, carbon tetrachloride, petroleum distillates glycerin and

oils.

Functional category

Coating agent, emulsifying agent, stabilizing agent, suspending agent,

tablet binder and thickening agent.

Applications in pharmaceutical formulation

HPC can be used as thickening agent, tablet binding, modified release and

film coating. Buccal delivery formulations containing HPC and polyacrylic acid

have been in use for many years with various ratios of the two polymers. HPC

offer interesting characteristics as controlled release matrices.

Incompatibilities

Hydroxypropyl cellulose in solution demonstrates some incompatibility

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35

2.7 Glycerin67

Synonyms

Croderol, E422, glycerine, 1,2,3 propanetriol, Glycon G-100,

trihydroxypropane glycerol.

Chemical name :Propane-1,2,3-triol.

Structural formula

Empirical formula : C3H8O3 Molecular weight : 92.10

pH : neutral to litmus

Density : 1.2656 g/cm3 at 15° C

Solubility : Miscible in water.

Description

Glycerin is a clear, colorless, odorless, viscous, hygroscopic liquid; it has

a sweet taste, approximately 0.6 times as sweet as sucrose.

Functional category

Antimicrobial preservative, emollient, humectants, plasticizer solvent,

sweetening agent and tonicity agent.

Applications in Pharmaceutical formulation

Glycerin is used in wide variety of pharmaceutical formulations including

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formulations and cosmetics, glycerin is used primarily for its humectants and

emollient properties. In oral solutions, glycerin is used as a solvent, sweetening

agent, antimicrobial preservative and viscosity increasing agent. It is also used

as a plasticizer and in film coatings. Glycerin is additionally used in topical

formulations such as creams and emulsions. Glycerin is used as a plasticizer of

gelatin in the production of soft gelatin capsules and gelatin suppositories.

Glycerin is employed as a therapeutic agent in a variety of clinical applications

and is also used as a food additive.

Incompatibilities

Glycerin may explode if mixed with strong oxidizing agents such as

chromium trioxide, potassium chlorate, or potassium permanganate.

2.8 Glutaraldehyde70,71

Synonyms

1,5-Pentanedial, 1,5-Pentanedione, Dioxopentane, Glutaral, Glutaralum,

Glutardialdehyde, Glutarol, Pentane-1, 5-dial, Pentanedial.

Chemical name : Glutaraldehyde, 1,5-Pentanedial.

Structural formula

Empirical formula : C5H8O2 Molecular weight : 100.12 g/mol

pH : 2.5-4.6

Density : 1.06 g/ml

Solubility : Soluble in water, alcohol, benzene

Description : Colorless liquid

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37

Application in pharmaceutical formulations

Glutaraldehyde has been also used for several decades as an effective

cross-linking agent for many applications including enzyme, cell immobilization,

polymeric drug delivery system and stabilization of protein crystals.

Glutaraldehyde is a chemical frequently used as a disinfectant and sterilizing

agent against bacteria and viruses (2% solution), an embalming fluid and tissue

fixative, a component of leather tanning solutions, and an intermediate in the

production of certain sealants, resins, dyes and electrical products.

Incompatibilities

(52)
(53)

38

The emergence of infection is associated with a large variety of wound

occurrences ranging from traumatic skin tears, burns and chronic ulcers

complications following surgery and device implantations. If the wound setting

manages to overcome the micro-organism invasion by a sufficient immune

response then the wound should heal. If not, the formation of an infection can

seriously limit the wound healing process. Evidence of increasing bacterial

resistance is on the rise and complications associated with infections are

therefore expected to increase. The main goal in treating various types of wound

infections is to decrease the bacterial load in the wound to a level that enables

wound healing processes to take place. Traditionally, the injured area should be

covered with antimicrobial cream once or twice every day. However, the patients

frequently suffer from discomfort during the application of topical drug in a

cream form. Furthermore, a substantial nursing effort is required for the

replacement of wound dressings. Recently, wound dressings or artificial skins

containing antibiotics have been developed for the inhibition of wound infection.

Wound infection can be decreased with the treatment of wound dressings, which

contain antimicrobials and the laborious replacement of wound dressings and the

damage inflicted on the newly formed epithelium can be avoided.

Fluoroquinolones, an effective and widely used antimicrobial agent for

wound and injuries in humans is employed as a active antibacterial drug for the

treatment of infected wounds. The newer fluoroquinolone, Gatifloxacin is a

broad spectrum antibiotic used for the treatment of infected ulcer, cellulitis,

traumatic wound, post operative wounds and burn infections. Currently these

problems are managed by administration of oral tablets. But, it can cause side

effects like tendonitis, central nervous system related effects like dizziness, head

ache and hypoglycemia. The local delivery of the drug by topical administration

may enable the maintenance of a high local antibiotic concentration for an

extended duration of release without causing systemic toxicity. Hence, a local

wound dressing that is biocompatible and produces a local effect with sustained

(54)

39 The objective of the present study is

To prepare and characterize a topically and locally effective, sustained

release Gatifloxacin loaded polymeric dermal patches.

To investigate the influence of polysaccharide polymers on the drug

release.

To evaluate in vitro biodegradability, biocompatibility and antimicrobial potency.

To compare the prepared formulations and to select the best based on

essential characteristics.

To investigate the skin toxicological evaluation using various models.

To assess the wound healing effect of Gatifloxacin loaded polymeric

dermal patches.

(55)
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40

Goldstein et al.72 determined the efficacy of Gatifloxacin compared to those of other quinolones against aerobic and anaerobic isolated from skin and

soft tissue samples of human and animal bite wound infections. The observations

revealed that fluoroquinolones especially fourth generation fluoroquinolones

have clinical efficacy in bite wounds.

Saleem et al.73 investigated the effect of topical gel formulations of 1% w/w Gatifloxacin developed by using different gelling agents like carbopol

934, Hydroxy Propyl Methyl Cellulose (HPMC) and sodium alginate. The

physicochemical properties were tested and in vitro release showed slow and extended release for a longer period of time. The gel formulations subjected to

antimicrobial assay showed higher efficacy than silver sulfadiazine. It was

concluded that topical gel with HPMC as gellant possessed good antimicrobial

and faster wound healing activity.

Martin and Zeigler74 reviewed the antimicrobial effect of

fluoroquinolones for uncomplicated and complicated skin and skin structure

infections and observed the fluoroquinolones especially newer agents,

Gatifloxacin and Moxifloxacin, possess higher potency against Gram positive

aerobes and Gram-negative anaerobes. It was concluded that fluoroquinolones

may reduce the antibiotic poly-pharmacy necessary to treat uncomplicated and

complicated infections in patients.

Blondeau et al.75 studied the in vitroactivity of fluoroquinolones against Gram-positive and Gram-negative organisms causing skin and skin structure

infections and concluded that second generation drugs have potent activity

against most Gram-negative organisms but less potent activity against

Staphylococci and Streptococci than third and fourth generation agents Gatifloxacin, Moxifloxacin, Gemifloxacin and Trorafloxacin. The MIC90 against

(57)

41

Tarshis et al.76 examined the effect of oral Gatifloxacin 400 mg/day in 121 patients and 500 mg oral levofloxacin 500 mg/day in 171 patients, in the

treatment of uncomplicated skin and soft tissue infections. The results concluded

that Gatifloxacin given once daily for 7 to 10 days was well tolerated and

effective as Levofloxacin given once daily for 7 to 10 days. The results showed

cure rate of 95 % for the Gatifloxacin treated patients and 88 % for the

Levofloxacin treated patients.

Nichols et al.77 comparatively evaluate Levofloxacin and Ciprofloxacin for uncomplicated skin and skin structure infections and the results was observed

clinical success of 98 % in Levofloxacin and 94 % in Ciprofloxacin treated

group.

Parish et al.78 investigated the safety and efficacy of Moxifloxacin and Cephalaxin in the treatment of uncomplicated skin infection and the resolution

and improvement was observed in 90 % of Moxifloxacin treated patients

compared with 91.5 % of Cephalexin treated patients.

Karchmel79 reported that fluoroquinolones appear to be highly efficacious

in the treatment of mild, uncomplicated and more severe, complicated skin and

skin structure infections. The older fluoroquinolones have excellent activity

against Gram-negative aerobic Bacilli and Psuedomonas. The newer quinolones developed to have enhanced activity against Gram-positive pathogens while

retaining broad spectrum against Gram-negative microorganisms.

Ball et al.80 reviewed the safety and tolerability of fluoroquinolones and concluded clinical data indicates that equivalency between compounds for

clinical outcomes, including microbiologic

Figure

Fig. 1 The structure of human skin
Fig. 2 Phases of wound healing
Table  18.  Surface pH of sodium alginate based dermal patches
Table  20.  Surface pH of gellan gum based dermal patches
+7

References

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