Thailand's state drug-making agency said yesterday (Oct 16) it would begin immediate production of the Aids drug didanosine, one of the best-selling treatments for the disease. The decision follows a recent court order that limited Bristol-Myers Squibb's patent on the drug to certain dosage levels, and represents a significant expansion of the government's capacity to produce its own versions of Aids treatments. Bristol-Myers Squibb has two weeks to appeal against the ruling by a Thai court this month that the patent on didanosine extends only to doses between 5mg and 100mg.

So far, however, the US pharmaceuticals company has remained silent on its intentions. But Dr Thongchai Thawichachart, director of the Government Pharmaceutical Organisation (GPO), said legal experts had determined that the government did not need to wait or seek additional court clearance in order to begin making and selling didanosine tablets at dosage levels not protected by the Bristol patent. Sudarat Keyuraphan, Thailand's minister of health, also supported the move, he said. "We already have the technology, and after this court decision we are able to produce [without] violating the law," Dr Thongchai said. "It is the requirement of our country immediately for the Ddi tablets."

The GPO already produces didanosine in a powder form, but Dr Thongchai and Aids activists say the tablets will be easier for patients to take and have fewer side-effects. The agency will initially produce about 5,000 tablets a day, and will then scale up to produce greater quantities, all for domestic consumption. The pills will be sold at prices around Bt20 (29 pence) for a 125mg tablet, less than half the price Bristol now charges for its tablets. The government agency has been marketing a version of AZT, another Aids drug, since 1995 and this year it started producing a pill that combines three different Aids treatments. Last week, Thai Aids activists filed an additional lawsuit in Thailand challenging Bristol's patent over the drug on the grounds that the medicine lacks sufficient innovation to warrant patent protection.

Some 700,000 Thais are living with HIV/Aids, while 250,000 more have died. Dr Thongchai said about 50,000 people in the country had access to anti-retroviral drugs. Following a massive public awareness and condom distribution campaign that began in the early 1990s, Thailand is viewed as one of the success stories among developing countries in dealing with the Aids epidemic.

A recent report by advisers to the Central Intelligence Agency said: "The government has probably averted millions of HIV infections." Brazil is the only developing country to make anti-retroviral drugs available free to all patients. Most of them are produced by state- owned plants. Didanosine, sold under the brand-name Videx, is one of about 15 anti-retroviral drugs that have made Aids a treatable disease in the developed world. Bristol recorded revenues of $259m (‡167m) from the drug last year.