ABSTRACT
Vipak is the transformed state of an ingested substance after digestion. This is also called Nisthapak, as opposed to Awasthapak or prapaka. Vipak is said to take place at the time of division of 'rasa' and 'mala' after digestion is completed but, as a matter of fact, it is finalized after the next 'paka' by bhutagnis in the liver where most of the drugs are metabolized. Virya is the potency by which the drug acts. Virya is more dominant in drugs, while rasa is more dominant in dietetic substances. Virya is interpreted differently in terms of guna,karma, or dravaya but the first view is accepted in practice. According to this, gunas potent enough to produce action are termed virya. The specific potency of a drug is known as prabhava. Thus, it is seen that two drugs, though having similar rasa, vipaka, and virya, differ in action.
