Drug acts in the body by virtue of certain qualities in them which are similar or dissimilar to the qualities present in different constituents in the body. In a very generalized form the effects of drugs have been summed up to be excitation (Vriddhi) and depression (Ksahya). These two general effects are brought about on the basis of the principles of similar (Samanya) and dissimilar (Vishesha). But then the defect or the deformity involves the systemic chain of pathogenic events leading on to the localization and manifestation of disease. Obviously, therefore, the pathogenic events should be dismantled at a particular site so as to break the chain and cure the disease. Different sites obviously include different Dushyas and Srotamsi along with their Adhisthan or Adhikaran. The ancient Rishis, therefore, thought of different prominent qualities in a drug by which it may act at particular site or at a particular pathogenic state. Since the pathogenic events do not simply imply the transport of pathogenic Dosha from Koshta to the
Basic concepts of Ayurvedic pharmacology 122 Dhatus, certain chemical changes and functional disturbances at each stage of Samprapti or pathogenesis were thought of. Secondly Dosha, Dushya and srotamsi involved in the pathogenesis have otherwise definite and distinct function to perform in the body in a close cooperative state. Keeping the quality and action of Dosha, Dushya and srotamsi in relation to pathogenic site, it becomes imperative for the scientists to explain drug action at different states of Samprapti and at different sites with different and defined qualities. If certain actions were to be ascribed to certain qualities they were to be named ‘Virya’ as the scientists were committed to the definition that anything of a drug that acts in the body should be called Virya. In view of this concept, Ashtavidha Virya becomes relevant as it goes to explain actions by Snigdha-Ruksha at the level of Koshta, Sheeta-Ushna at the level of srotamsi and Guru –Laghu at the level of Dhatu. Let us now recall the statement of Charak about how drug acts –
Whatever, therefore, substances do, whether by virtue of their nature as substance, or by virtue of both, their substantive and qualitative natures, in any given time, at any given place, having been administered in a given mode, with a given result in view – all that is their action. Whereby they act is the potency. Wherein they act is the time. How they act is the mode, what they achieve is the result (Ch. Su. 26/13).
The above statement asserts the importance of the substances as obviously qualities without substances are inconceivable. In the above statement two words attract our attention – Dravya Prabhavat and Gunaprabhavat. This implies that certain actions may not be explainable on the basis of qualities of the drugs. This idea corresponds to ‘Isomerism’
which is appropriately christened as Prabhava in Rasapanchaka. The
Basic concepts of Ayurvedic pharmacology 123 remaining Rasa, Vipaka, Guna, Virya are implied by ‘Guna Prabavata’. The statement further adds the consideration of Adhikarana and also the actions and results. It is, therefore, imperative for us to explain the mode of action in relation to the site of action. The mode of action according to us would be to rectify the discordance in the Dosha, Dushya and Srotamsi and these even though present throughout the body have certain prominence and locations.
This is one aspect. The another aspect is that the drug acts by virtue of Rasa, Vipaka, Guna and Virya. If the drug acts by Virya (ENA KURVANTI TAT VIRYAM) and if the drug action as per the foregoing statement is done by Guna Prabhava, some of the prominent Gunas should be involved in explaining the actions through Rasa, Vipaka and Virya. And this postulation is true because even the Rasa and Vipaka are said to exert their influences on the tongue or on the Koshta mala and mutra by virtue of qualities they have.
This is the main basis on which Ashtavidha Virya Vada stands and this is why, on an overall assessment of the relevant facts and literature, we are tempted to prefer Ashtavidha Virya Vada to explain drug action in Ayurveda. However this does not amount to deny the Dwividha Virya Vada as it is also included in Ashtavada. Being a clinician Maharshi Charak seems to attach more importance to Dwividha Virya Vada. But he himself never condemns the Ashtavidha Virya Vada. When different but unconflicting approaches are made to one problem, a comprehensive approach is preferable and this is what makes us to support Ashtavidha Virya Vada.
A comprehensive study of the general and specific principles of drug in Ayurveda reveals one fact beyond doubt that drugs act by Virya which is entertained and interpreted in different ways keeping in view the chemical, biological and therapeutic equivalences including Rasapanchak vis-à-vis the Dwividha and Asthavidha Viryas with special reference to the mode of
Basic concepts of Ayurvedic pharmacology 124 action, selective affinity and therapeutic utility. At the very outset the Virya has been divided in two groups – chintya Virya incorporating the Rasa, Vipaka, Guna and Virya and the Achitya Virya denoting the Prabhava. The scientific rationality rests with the Rasapanchaka sineque non for drug action finding its final expression in Dwividh or Ashtavidha Virya pari pasu the therapeutic utility envisaged in shadupakrama. There is, inter alia, a relationship between these principal postulates at the chemical and therapeutic levels, their independent identity - not withstanding. The concept of Ashtavidha Virya is a comprehensive, nonetheless, all – inclusive approach to drug action, which purports to dismantle the Samprapti at any particular stage so as to avail of the ultimate desired therapeutic effect. In the preceding pages it is attempted to collaborate and corroborate Raspanchaka with Ashtavidha Virya in relation to Samprarti Vighatana. The preference to Ashavidha Virya depends on its being inclusive of Dwividha Virya. An attempt has been made to define and determine specific place with specific function on the one hand and specific quality, the specific therapeutic utility the other. Thus the whole chain of Samprapti, inevitably and invariably involving the Doshas, the Dushyas and Srotamsi has been located at the level of Koshta (Dosha), Srotas and Dhatu. Each of these three require to be corrected by stimulating or depressing as the case may be and, therefore, six most potent qualities have been picked up to be named as and included in Virya – Snigdha – Ruksha at the level of Koshta, Sheeta – Ushna at the level of Srotas and Guru-Laghu at the level of Dhatus. Moreover to insure drug identification along with its primary qualities and their local actions the Mrudu and Tikshna Gunas have also been accepted as Viryas at the tongue level. Thus Ashtavidha Virya encompasses all the aspects of drug action. The Shadwidhopakramas are but the expression of Ashtavidha Virya in therapeutic parlance. There is no controversy or contention between
Basic concepts of Ayurvedic pharmacology 125 Ashtavidha and Dwividha ViryaVada, as the former, ipso facto, includes the latter.
At length, it is now clear that a multi-farious and synthetic approach, on the applicability of various concepts of drug action was adopted in Ayurveda, showing thereby that these schools are not contradictory but they are rather supplementary to one another.