COMUNICACIONES FORMATO PÓSTER
VALIDATION OF A MICROEMULSION ELECTROKINETIC METHOD FOR THE LIPOPHILICITY DETERMINATION OF ACIDIC COMPOUNDS
Xavier Subirats, Lídia Redón, Martí Rosés
Institute of Biomedicine (IBUB) and Department of Chemical Engineering and Analytical Chemistry, Universitat de Barcelona
Martí i Franquès 1-11, 08028 Barcelona [email protected]
Lipophilicity, which represents the affinity of a molecule for a lipophilic environment, is a relevant physicochemical property to be determined in the drug discovery and design process [1], since it plays a fundamental role on drug absorption, distribution, metabolism, excretion, and toxicity (ADMET). The lipophilicity of a compound is commonly measured by its distribution behavior in a
n-octanol/water biphasic system. It is normally referred to unionized species, even in the case of compounds with acid/base properties, and reported as the logarithm of the partition ratio (log Po/w). Besides its importance in drug development, given that lipophilicity is a critical parameter for chemical safety assessment, according to the REACH Regulation ((EC) No 1907/2006) log Po/w values must be reported for any organic compound produced in quantities of one tonne or more per year. Two test procedures are described in the Test Methods Regulation ((EC) No 440/2008): a direct measurement via the shake-flask method [2] and a correlation approach using the HPLC method [3]. However, other experimental methods can be used provided that they show an acceptable level of quality assurance [4].
Several chromatographic methods were proposed for lipophilicity determination, mainly using reversed-phase columns and buffered mobile phases containing acetonitrile as organic modifier [5]. Although these approaches are significantly time-saving, they normally require the introduction of molecular descriptors for hydrogen-bond acidity [5–8] and are less accurate (±0.5 [3]) than shake-flask methods (±0.3 [2]). Microemulsion electrokinetic chromatography (MEEKC) is a very interesting alternative for lipophilicity measurement, given that the oil droplets acting as pseudostationary phases are better surrogates of n-octanol/water systems than reversed-phase columns. In fact, MEEKC measurements can be accurately correlated with log Po/w without the need of molecular descriptors [9,10].
In the present work a high-throughput methodology for log Po/w determination of acidic compounds (pKa > 3) was proposed and validated using conventional CE instruments with UV detection and uncoated fused silica capillaries. The ME consisted of 1.3% (w/v) SDS, 8.15% (v/v) 1-butanol, 1.15% (v/v) heptane, and 20 mM phosphoric acid, pH 2.0. 3-methylbenzoic acid, phenobarbital, barbital, and thiouracil were proposed as calibration standards, allowing the measurement of log
Po/w values in the range comprised between -1.54 and 4.01 with a prediction accuracy not worse than 0.4.
[1] J.A. Arnott, S.L. Planey. Expert Opin. Drug Discov. 7 (2012) 863–875.
[2] OECD, Test No. 107: Partition Coefficient (n-octanol/water): Shake Flask Method, OECD Publishing, 1995. [3] OECD, Test No. 117: Partition Coefficient (n-octanol/water), HPLC Method, OECD Publishing, 2004. [4] ECHA, Guidance on Information Guidance on Information Requirements and Chemical Safety Assessment.
Chapter R.7a: Endpoint specific guidance, 2016.
[5] K. Valkó, Physicochemical and Biomimetic Properties in Drug Discovery, Wiley, Hoboken, NJ, USA, 2014. [6] J.M. Pallicer, S. Pous-Torres, J. Sales, M. Rosés, C. Ràfols, E. Bosch. J. Chromatogr. A. 1217 (2010) 3026–3037. [7] J.M. Pallicer, R. Pascual, A. Port, M. Rosés, C. Ràfols, E. Bosch. Eur. J. Pharm. Sci. 48 (2013) 484–493.
[8] X. Subirats, M. Rosés, E. Bosch. J. Pharm. Biomed. Anal. 127 (2015) 26–31. [9] Y. Ishihama, Y. Oda, K. Uchikawa, N. Asakawa. Anal. Chem. 67 (1995) 1588–1595.
PO-FC-02
APPLICATION OF QbD APPROACH AND NIR TECHNOLOGY FOR THE QUALIFICATION OF A FREEZE-DRYING PROCESS
G. Clua1,2, L. Garcia1,2, S. Nikolic1, E.Jo1, J. Coello 2 and Maspoch S2
1Center of Excellence in Lyophilization, Reig Jofre Group
2Department of Chemistry, Universitat Autonoma de Barcelona, 08193 Bellaterra,
In the pharmaceutical industry, freeze-drying is used to transform solutions of active ingredients, with or without excipients, in sterile solid products which are more stable. The definition of a freeze-drying process that maximizes the speed of sublimation while preserving the quality of the product is of great industrial interest. In the framework of Quality by Design (hereinafter QbD) and using a risk based approach, historical data analysis was combined with new experimental studies in order to define a broader knowledge space and propose a design space for the sublimation phase of the freeze-drying process. The design space was defined as a combination and multidimensional interaction of process parameters that describes a region in which the quality of the product is preserved.
A Doehlert design of experiments was executed with 2 factors (temperature and pressure) and the sublimation time, appearance and reconstitution time were evaluated as responses. The product complies with the specifications throughout the experimental regions. Then, the results of sublimation time were adjusted to a MLR model. The model fits perfectly to a linear regression (R2 = 0,996) and has a high predictive capacity (Q2 =0,967). Regarding the coefficients, the temperature factor is the predominant to predict the duration of the sublimation. Finally, the obtained model was used to predict the optimum conditions and justify the operational settings. The newly developed process was scaled-up to the industrial plant and a manufacturing batch at the border of the proposed design space was put into stability studies.
After the development and successful scale-up, the process was qualified. The increased number of samples for residual water analysis was handled by means of near infrared spectroscopy due to its capability to determine large number of samples in a non-invasive and non-destructive analysis, giving an accurate result and requiring minimal or no sample preparation. It was used to perform a moisture mapping to statistically assess the variability among distinct positions, shelves, and freeze-dryers, and establish the correct sampling plan during routine production. For this purpose, a near infrared model was developed and validated according to the methodology recommended in EMA guidance and ICH Q2. After, the predicted residual water content results were plotted in a 3D representation of the freeze-dryers chamber to visualize the spatial distribution of the residual vials in the vials inside the freeze-dryers. The project was developed in collaboration with the Spanish Medicines Agency (AEMPS).
PO-FC-03
DETERMINATION OF POLYCYCLIC AROMATIC HYDROCARBONS IN