In Ayurvedic classics the concept of Agni is well elaborated; considering the Physiological point of view, Agni is the basic essential in digestive process.

Any food substance or medicine has an interaction with Agni for its metabolism and absorption. Agni itself is a vast and individualized concept making its action different with each biotype. This leads to a different and unique pattern of drug interaction or possible mode of interaction depending on the biotype and associated Agni factor as described in Ayurveda. The Vata dominant people will show more variability in the digestive period as compared with other constitutions; similarly Pitta dominant people will show fast metabolism and Kapha dominant people will show a slow metabolic processes considering their Agni as per the concept of Prakriti. With consideration of pharmacological point of view drug metabolism comes under the domain of Pharmacokinetics or in other words how body handles the drug. It includes drug absorption, distribution, metabolism and excretion.

This concept of Ayurveda with consideration of Agni and biotype is an influential factor on drug metabolism. As discussed earlier, Vata dominant people will show unpredictable drug absorption, Pitta prakriti people will show a faster drug absorption and metabolism compared to others. While the Kapha prakriti will have a comparatively slower drug metabolism. Usually drug metabolism helps to eliminate the drug through excretory pathways mostly from kidneys as urine. The rapid absorption of the drug helps to achieve faster drug concentration and faster drug distribution in various bodily compartments thus drug distribution in various tissues is a rapid process. In Pitta dominant people the fate of drug in, through and out of the body will be the fastest of all. They will metabolize the drug faster than the other biotypes.

Hence higher dose of a drug will cause the adverse reactions or side effects commonly observed in Pitta dominant people, especially when the drug is expected hot in potency. These people are highly reactive to the triggering factors making their body react faster with the drugs.

Long term adverse effects will be commonly observed in Kapha dominant people. Kapha people may require a larger dose to achieve EC 50 and its efficacy. Considering these aspects, selection of a proper drug as per constitution is utmost important.

It is considered that for effective drug action absorption is must; it is pharmacologically true in modern perspective. However when the drugs come in contact with human sensory organs, they modify their physiological processes through the Vata regulation. Vata is the principal of movement and Gati and Gandhian (Motor and Sensory) are controlled by Vata.

Veerya Concept shows similarity with the principal of Drug Potency with the weight to weight comparison of a drug action. Veerya and Vipak concepts are determined by physiological modifications through the drugs. Gamitva concept of Ayurveda explains the drug affinity, drug receptors and their binding with the drugs. Gamitva is attractive force in between the drug molecules and tissues. Receptors have specificity for particular drug components. Ayurvedic physiology explains that the similar factors show affinity towards each other and vice versa. Here structural complimentary features like lock and key methods should be considered. Drugs either modify the electrical activity of the cells or they modify the secretions. In tissues like muscles and nerves the Action Potentials are generated through the modification of various channels. These electrical activities, secretary functions are nothing but the Vata regulation.

Prabhav can be explained on the basis of pharmacological principles on individual drug. In day to day practice it has been observed that people are taking multiple drugs from the different pathies; in this situation the drug interactions are beyond our imagination. Hence it is essential to keep 2 -3 hours gap in between two types of drugs. Ayurvedic therapeutics advocates the different time schedule for the drug administration to target specific body parts which are under control of different subtypes of Vata. Ayurveda has also recommended specific schedule to target the drug in specific pathogenesis or in disease E.g. in Tamak Shwas frequent dose is recommended. Consumption of drugs or medicine on empty stomach is recommended for Rasayan purpose; while drugs given before meal are indicated to target the lower part of the body which is under control of Apan Vayu.

This wisdom of Ayurvedic experts in those days was incredible. Different drug vehicles are recommended in Ayurvedic Classics. These vehicles modify the Pharmacokinetics and pharmaco-dynamics in a favorable manner. In an experiment at a laboratory it has been observed that the absorption of Tamra bhasma was maximum with Lemon Juice followed by Kumari asavum. Even the ascorbic acid didn’t help to increase the drug absorption which was included in the same study.

Experts have explained Shodhan, Maran and Amrutikaran for various metals. From above experimental observations one can easily understand that all the processes recommended in the classics were not only for removing the toxic components and only preparation of the organic drugs, rather they were utilized stringently for drug potency, efficacy and proper drug targeting to a desired site of action.

Ayurveda students should learn their science in a holistic manner and should use it in their clinical practice. Also be open to let the experts from other system of medicine take efforts to understand Ayurvedic therapeutics in their own scientific perspective.