The attempt to develop potential drugs from plant based classical ayurvedic formulations would be more effective if the ancient disorders can be identified in contemporary terms or modern disorders discovered in ancient descriptions, feels Dr M S Valiathan, former Vice Chancellor of Manipal Academy of Higher Education. In his recent book "The Legacy of Caraka", Dr Valiathan observes that the search for new chemical entities and potential drugs from the old plants would undoubtedly become better focused by this approach.

Noting that Caraka's formulations for oral, nasal, dermal, rectal and other applications were based on hundreds of plants, Dr Valiathan said that the drug formulations in "Caraka Samhita" represented a large collective experience and formed the core of a national formulary in Caraka's time (1 A D). "A study of the burden of diseases in the Caraka Samhita is rewarding not only for the practicing ayurvedic physicians but also for a modern investigator who screens the old medicinal plants for new chemical entities. The present exercise is often a "hit or miss" because it seeks to study rarely known plants that had been used long ago for disorders that are even less known today," he explained.

"It is not often realized that medicinal plants continue to play an important role in the development of therapeutic agents today. At the global it is estimated that 130 drugs are single chemical entities derived from higher plants or modified synthetically. Similarly it is believed that 75 - 80 per cent of the world population (mainly in developing countries) depends on crude plant drug preparations for their healthcare needs. Obviously, accessibility to a large library of compounds is essential for drug discovery from plants. But the screening tends to become wasteful unless the numbers to be screened are reduced on a rational basis. It is in this context that the formulations mentioned in samhita assumes special importance," Dr Valiathan said.

According to Dr Valiathan "If diseases as recognized and known today could be disengaged from among the ancient descriptions, one would know the precise formulations that had been prescribed for those diseases and be in a position to prepare a purposeful shortlist of plant extracts for screening." The opportunities for developing drugs for treating a variety of diseases (particularly degenerative diseases) from the wealth of ayurvedic formulations and individual plants are vast, he noted.

"The Legacy of Caraka", published by Orient Longman Private Limited, is a paraphrase of all the 120 chapters of the original text, in contemporary idiom. A short introductory section contains Dr Valiathan's observations on some of Caraka's basic concepts and their relevance to the practice of medicine today. The book retells the samhita in a new format. Instead of adhering to the sequence of the sthanas in the original, the author has retold the samhita through thematically structured chapters, in contemporary idom.

Caraka Samhita is the foundational text of ayurveda, India's traditional system of medicine. Caraka, the physician extraordinare of ancient India, is believed to have lived in the first century AD, as a contemporary and companion of King Kanishka. Caraka Samhita was, in fact, a revision of an older text Agnivesa Tantra, which was written several centuries before Caraka's time. Caraka's revision became so popular that it was translated into Tibetan, Arabic, English and Indian languages. Recently, a digitized version was prepared by Professor Yamashita of Kyoto University, Japan. A Caraka club flourished in the early twentieth century in New York and included among its members, Sir William Osler.