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=== Introduction ===

=== Introduction ===

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The scope of Ayurveda was envisaged by the acharyas under three key principles: ''hetujnana'' (knowledge of etiology), ''lingajnana'' (symptomatology) and ''aushadhajnana'' (knowledge of therapeutics). Etiology includes the immediate and distant causes of diseases. Symptomatology includes the signs and symptoms of diseases and health. In continuation of the series on ''annapana chatushka'' (tetrad on dietetics), the present chapter is on understanding the basic principles of Ayurvedic pharmacology (''aushadhajnana''). ''Aushadhajnana'' encompasses materia medica and therapeutics. ''Dravya'' (matter), ''guna'' (quality), ''karma'' (action), ''samanya'' (that which results in similarity), ''vishesha'' (that which results in exclusivity) and ''samavaya'' (inseparable or permanent relationship or concomitance) constitute ''karana'' (causes, reasons or means) for achieving good health by restoration of ''dhatu samyata'' (equilibrium of ''dosha,'' tissue elements).  

The scope of [[Ayurveda]] was envisaged by the acharyas under three key principles: ''hetujnana'' (knowledge of etiology), ''lingajnana'' (symptomatology) and ''aushadhajnana'' (knowledge of therapeutics). Etiology includes the immediate and distant causes of diseases. Symptomatology includes the signs and symptoms of diseases and health. In continuation of the series on ''annapana chatushka'' (tetrad on dietetics), the present chapter is on understanding the basic principles of Ayurvedic pharmacology (''aushadhajnana''). ''Aushadhajnana'' encompasses materia medica and therapeutics. ''Dravya'' (matter), ''guna'' (quality), ''karma'' (action), ''samanya'' (that which results in similarity), ''vishesha'' (that which results in exclusivity) and ''samavaya'' (inseparable or permanent relationship or concomitance) constitute ''karana'' (causes, reasons or means) for achieving good health by restoration of ''dhatu samyata'' (equilibrium of ''dosha,'' tissue elements).  

''Dravyas'' are of three categories - some alleviate ''doshas,'' some vitiate ''dhatus,'' and some are good for the maintenance of positive health. ''Dravyas'' act with the help of their inherent qualities (''guna''). ''Dravya'' acts by its nature or with the help of its inherent qualities. It is emphasized that no medicine should be prescribed for incurable diseases and curable conditions should be treated with ''bheshaja'' (medicine) possessing opposite qualities (to those of the conditions being treated), administered with due regard to ''desha'' (the area or region where the drugs are produced or collected), ''matra'' (appropriate dose) and ''kala'' (seasonal variations as well as the age of the patient). The success of the treatment primarily depends on the principles involved in processing and prescribing the drugs that are collectively called ''paradi gunas'' (10 general attributes). The key factor responsible for the manifestation of the effect of the drug is referred to as ''veerya''. ''Veerya'' is the power that performs ''karya'' (work or activity). The site of action of one drug is referred as ''adhikarana'', and bodily components like ''dosha, dhatu, mala, agni, srotas'' and mind may be considered as ''adhisthanas''. ''Upaya'' indicates the mode of administration and the consequent outcome of the ''upaya'' is ''phalam'' (which ideally should be the restoration of equilibrium of all the functions of body and mind). About principles of drug action ''rasa, guna, veerya, vipaka'' and ''prabhava'' are considered to be the prime factors that trigger the drug’s actions. This is referred to as ''gunaprabhava'' (literally, effects of the qualities).

''Dravyas'' are of three categories - some alleviate ''doshas,'' some vitiate ''dhatus,'' and some are good for the maintenance of positive health. ''Dravyas'' act with the help of their inherent qualities (''guna''). ''Dravya'' acts by its nature or with the help of its inherent qualities. It is emphasized that no medicine should be prescribed for incurable diseases and curable conditions should be treated with ''bheshaja'' (medicine) possessing opposite qualities (to those of the conditions being treated), administered with due regard to ''desha'' (the area or region where the drugs are produced or collected), ''matra'' (appropriate dose) and ''kala'' (seasonal variations as well as the age of the patient). The success of the treatment primarily depends on the principles involved in processing and prescribing the drugs that are collectively called ''paradi gunas'' (10 general attributes). The key factor responsible for the manifestation of the effect of the drug is referred to as ''veerya''. ''Veerya'' is the power that performs ''karya'' (work or activity). The site of action of one drug is referred as ''adhikarana'', and bodily components like ''dosha, dhatu, mala, agni, srotas'' and mind may be considered as ''adhisthanas''. ''Upaya'' indicates the mode of administration and the consequent outcome of the ''upaya'' is ''phalam'' (which ideally should be the restoration of equilibrium of all the functions of body and mind). About principles of drug action ''rasa, guna, veerya, vipaka'' and ''prabhava'' are considered to be the prime factors that trigger the drug’s actions. This is referred to as ''gunaprabhava'' (literally, effects of the qualities).

*''Rasa'' (taste) of any substance is six in number, and the source element for the manifestation of all forms of tastes is ''jala mahabhuta''.

*''Rasa'' (taste) of any substance is six in number, and the source element for the manifestation of all forms of tastes is ''jala mahabhuta''.

*According to the science of Ayurveda, all matter (animate or inanimate) is made up of the five ''mahabhutas'' (five basic elements).

*According to the science of [[Ayurveda]], all matter (animate or inanimate) is made up of the five ''mahabhutas'' (five basic elements).

*The matter is the substratum of ''rasa''.

*The matter is the substratum of ''rasa''.

*There is nothing in the world which does not have therapeutic value, and at the same time, everything cannot be used for the treatment of every disease.  

*There is nothing in the world which does not have therapeutic value, and at the same time, everything cannot be used for the treatment of every disease.  

====== ''Prabhava'' ======

====== ''Prabhava'' ======

It is quite apparent that the ''acharyas'' formulated the hypothesis that explained the workings of drugs after observing various activities. In the context of the failure of the hypothetical principles to explain the drug action in a rational way, the concept of ''prabhava'' was formulated which may be interpreted as an empirical principle. Drugs with similar chemical structure should have similar actions. But it is not possible to predict the activity of a drug entirely by its chemical structure. Drugs with similar structures but having entirely different effects are known as isomers, for example, Antazoline and Tolazoline appear chemically similar but former is an antihistamine and the latter is an adrenergic blocking agent. Conversely, many dissimilar chemical agents have similar action, for example, phenobarbitone, chloralhydrate, and paraldehyde are all depressants of the central nervous system. The concept of ''prabhava'' may be interpreted using the concept of isomerism<ref>Dwarkanath C.,The Fundemental Principles of Ayurveda, Chaukhambha Sanskrit Series, Varanasi; 2009: pp-180 </ref>.

It is quite apparent that the ''acharyas'' formulated the hypothesis that explained the workings of drugs after observing various activities. In the context of the failure of the hypothetical principles to explain the drug action in a rational way, the concept of ''prabhava'' was formulated which may be interpreted as an empirical principle. Drugs with similar chemical structure should have similar actions. But it is not possible to predict the activity of a drug entirely by its chemical structure. Drugs with similar structures but having entirely different effects are known as isomers, for example, Antazoline and Tolazoline appear chemically similar but former is an antihistamine and the latter is an adrenergic blocking agent. Conversely, many dissimilar chemical agents have similar action, for example, phenobarbitone, chloralhydrate, and paraldehyde are all depressants of the central nervous system. The concept of ''prabhava'' may be interpreted using the concept of isomerism<ref>Dwarkanath C.,The Fundemental Principles of [[Ayurveda]], Chaukhambha Sanskrit Series, Varanasi; 2009: pp-180 </ref>.

=== References ===

=== References ===