The substance DK-1, which the scientists hope to use as a vaginal contraceptive in the form of a cream or pessary, has been isolated from the volatile fraction code-named NIM-76 separated from neem oil. According to M. Selvamurti, DIPAS director, the substance is a potent germicide at a concentration of less than 0.2 per cent.

Pharmacological and acute toxicity trials on rats, rabbits and guinea pigs, carried out at the Central Drug Research Institute in Lucknow, have cleared DK-1 for phase-one human trials, due to begin in November. Selvamurti says these will be followed by a large-scale trial in 1996.

The institute has transferred the technology to two Indian drug companies who will scale-up production of the neem contraceptive to produce the supplies needed during the phase-two trial and subsequent marketing. DIPAS scientists say that neem's historical role as part of Indian folklore may make it more socially acceptable as a contraceptive than conventional birth control pills.

Tests have shown that DK-1 is stable at 45'C. and has a shelf-life of at least six months. The neem isolate, says Selvamurti, has been subjected to the rigorous tests needed for pharmaceutical regulation. The contraceptive formulation will be licensed - unlike other herbal preparations, whose biological effects tend to show considerable variation.