Vipaka and its working in the process of digestion and how it affects the action of various drugs
Charaka wrote ‘Everything in the universe has medicinal application’. Agnivesha told his teacher that he was not able to locate any plant without medicinal application. Before the evident of modern medicine, the man was completely dependent upon medicinal plants for curing as well as preventing diseases. Ancient scholars preserved their work on medicinal plants in form of Nighantus. Later on the subject Dravyaguna came into existence and it has a significant place in Ayurvedic system of medicine. Scholars of the western countries wrote Materia Medica, the term coined for the subject dealing with the study of drugs derived from natural source. Materia Medica has been largely replaced by term Pharmacognosy.
It deals with the study of drugs derived from natural (plant, animal or marine) origin. In the recent past, the study of Dravyaguna has become more important because of global acceptance of Ayurvedic system of medicine. Ayurveda has its viewpoint, as far as drug formulation is concerned. Ayurveda decribes, Rasa, Guna,Virya, Vipaka, Prabhava and Karma, for all medicinal drugs or agents and these represent the pharmacological aspects of formulation used in Ayurveda.
Charka Samhita and Sushruta Samhita are Ayurvedic classics of medicine and surgery respectively. The botanical identity of the medicinal plant is of utmost importance as numbers of plants documented with the same name. Drug identity is a bit controversial subject in Ayurveda, although most of the plants described in Ayurvedic texts have been assigned Latin names. Ayurveda was practiced in a commentary form and students were taken to forests for the identity of the plant. We are dependent on herbal vendors and folklore medicine for tracing valuable remedies.
Charka has classified Dravya into the following categories:-
- According to origin, plant and animal source.
- According to pharmacologial activity like bronchodilator, laxative, lithontriptic.
Ayurveda is an interdisciplinary science, and medicine, yoga, meditation, gem and metaphysical approach are integral part of it. When we discuss the drug action, Ayurveda, unlike Allopathic uses the drug as a whole. Drugs are dispensed as pharmacopoeial preparations such as as aromatic water, powder, infusion, decoction, ointment, syrups or confections Dravyaguna deals with the study of drugs derived from nature and Rasa-Shastra deals with study of minerals. Drug formulation in Ayurveda is based on following seven parameters:
- Dravya (Substance)
- Rasa (Taste)
- Guna (Property)
- Virya (Potency)
- Vipaka (Post-digestion effect)
- Prabhva (Therapeutics)
- Karma (Pharmacological activity)
Dravya is described as a substance used for medicinal purpose. According to Ayurvedic theory, every component of the universe is dravya and has medicinal value. Drugs derived from herbs, minerals and animal source, are included among dravya. Charaka Samhita, the Ayurvedic treatise on medicine, has mentioned dravya to be the nucleus of Ayurvedic pharmacy.
Vipaka is defined as the final taste of a drug, which is encountered after exposure to digestive enzymes. It is comparable with the metabolism of the drug. Alternatively, vipaka can be defined as the final outcome of the biotransformation of the rasa (taste) of a dravya through the action of digestive enzymes (comparable with jatharagni). Although, number of theories have been put forward, but generalized view is that vipaka is of three types; sweet, sour and pungent.
Vipaka of Dravyaguna can be compared with pharmacokinrics, a brach of pharmacology, the study of drugs. The process of vipaka is initiated in grahani, the first part of the small intestine. According to Charaka’s view point, the work of is evident at Vipaka works at level of koshtagni or humour. This statement falls well in the category of human physiology. Sushrut describes that site of action of guru and laghu Vipaka is at dhatu (tissue) level, which more or less fits in clinical level.
The Vipaka of Various Tastes are Tabulated Below
| Taste | Vipaka (Post digestion effect) |
| Sweet | Sweet |
| Sour | Sour |
| Salt | Sweet |
| Pungent | Pungent |
| Bitter | Pungent |
| Astringent | Pungent |
Table 1: It shows vipaka of six tastes
Action of Different Types of Vipaka
| Vipaka (Post digestion effect) | Actions |
| Madhura | Unctuous, heavy, aggravates Kapha, anabolic, spermopiotic, laxative and diuretic |
| Amla | Unctuous, light, aggravates Pitta, depleting effect on tissues, laxative and diuretic |
| Katu | Ununctuous, light, aggravates Vata, depleting effect on tissues and induces constipation |
Samanaya Pratyayarabdha Dravya
The drugs are classified according to potency as hot or cold. Every drug mentioned in Ayurvedic texts irrespective of the fact it is derived from plant or animal or marine source, has specific potency. In Ayurvedic language, such drugs are known as Samanaya pratyayarabdha dravya.
Vichitra Pratyayarabdha Dravya
Some drugs are exception to the concept of Samanaya pratyayarabdha. Depending on metabolic and chemical changes a substance goes in human body, the configuration of a substance changes and taste or potency may change. In Ayurvedic language such drugs are known as Vichitra pratyayarabdha dravya. For instance sunthi (Zingiber officinale) has pungent taste but sweet in vipaka.
