The drug formulation in Ayurveda is based on two principles:

A. Use as single drug.

B. Use of more than two drugs.

When two or more herb are used in formulations, they are known as polyherbal formulations. Some time herbs are combined with mineral preparations also. The herbs often exist in crude state and Ayurveda describes method of purification of toxic herbs. The concept of polyherbalism is peculiar to Ayurveda although it is difficult to explain in term of modern parameters. Sanghar Samhita highlights the concept of synergism behind polyherbal formulations.

Ayurveda has fundamental aspects for drug formulation. The herbs are selected according to the disease; other herbs are used to prevent the side effects arising from chief herb. Typical formulations for fever inculde bitter herbs, like Parpatadi quath , Kirat-tikatadi quath . The polyherbal have been used for centuries and some like Triphala , Trikatu are integral part of formulations marketed for digestive disorders.

Today, chromatographic methods HPLC, GC, HPTLC are used for identifying active constituent of medicinal herbs. The scientific procedures have brought revolution in the field of herbal medicine, particularly in case of single plant based formulation. The concept of standardisation is fastly catching with herbal products based on active constituent.

Ayurveda strongly recommends the use of the plant as a whole. Rauwolfia serpentina ( Sarpagandha ), the biological source of antihypertensive alkaloid, reserpine, when used in powdered from, is devoid of unpleasant side effects.

Reserpine was once regarded as potent treatment of hypertension, was withdrawn due to unpleasant side effects. Sarpagandha adi churna, is traditional Ayurvedic remedy for hypertension and is still use by practitioners of Ayurveda with success.

Single plant based formulations may have better acceptance from quality control and standardisation aspects, but still not ample amount of evidence has accumulated to prove concept of standardisation of herbal drugs based on single constituent.

Hypericum perforatum , commonly known as bassant in Ayurveda, has shown clinical efficacy in mild to moderate depression. It has been concluded that neither hypericin nor hyperforin alone presents the anti depressant constituents of Hypericum perforatum , but other compounds like flavonoids and xanthones also contribute to the anti depressant activity.

Allium sativum (garlic) is used for the treatment of hyperlipidemia and hypertension. Ayurveda describes a formulation ? Rason Kalpa ' for treatment of rheumatic diseases. Modern research has thrown light on pharmacological activites of garlic and allicin and ajoene are considered to be the active constituent of garlic.

Garlic also contains compounds like triterpenoids and fructans have pharmacological activity and are believed to contribute to hypolipidemic and anti cancer effects of garlic.

Polyherbal formulations are difficult to standardize. The plant is a biosynthetic laboratory for chemical compounds like glycosides, alkaloids etc. These exert physiological and therapeutic effect. In 1500 B. C. Hippocrates, a Greek physician, prescribed leaves and bark from Salix alba (willow tree) to relieve fever and pain.

Researchers in the last century identified and isolated Salicin, a glycoside as active principle. From salicin, salicylic acid and finally aspirin was synthesized. Aspirin is known to cause gastric irritation and hypersensitivity. The plant when used alone does not cause gastric irritation, probably due to the presence of tannins.

It can be concluded that polyherbal formulations should not be dismissed only on the basis that they do not withstand modern research. Ayurveda and herbal medicine has roots in medicinal herbs and they have been practiced for centuries.

Herbal medicine is making dramatic comeback and increasing number of patients are visiting alternative medicine clinics. Side effects of synthetic medicine are alarming and recent time has seen risk of herbal ?herbal and herbal-synthetic drug interactions. Under the prevailing circumstances futher investigations into the concept of polyherbal formulations should be undertaken.

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