India’s Ranbaxy Laboratories Ltd. said the World Health Organisation (WHO) had re-included seven of its anti-AIDS generic drugs in its pre-qualification list after the drugs were taken off last year due to discrepancies in tests.

The WHO dropped three of Ranbaxy’s generics last August, saying they had not been proved to be equivalent to patented counterparts, and India’s top drug maker then withdrew its remaining eight antiretrovirals from the WHO list in November.

The WHO says generic drugs are key to treating AIDS in the developing world, with about half of those on AIDS drugs in poor countries taking generics - mostly made by Indian companies.

Ranbaxy said in a statement late on Thursday that it had used globally recognised contract research organisations to carry out bio-equivalence studies for its antiretrovirals. The drugs are manufactured at Ranbaxy’s plants, which have been approved by both the WHO and the U.S. Food and Drug Administration.

Ranbaxy said the drugs on the list are two combinations of lamivudine, nevirapine and stavudine, two combinations of lamivudine and stavudine, a combination of lamivudine and zidovudine and tablets of each of those two.

The WHO’s prequalification list aims to make it easier for countries to decide which medicines to buy when they are planning anti-AIDS campaigns.

Ranbaxy has also been seeking FDA approval to qualify for inclusion in U.S. programmes for AIDS drugs relief. The FDA has so far given it tentative approvals for three drugs.

There is currently a gap between the WHO approach to selecting medicines for the developing world and that of the United States, which requires all drugs supplied to its AIDS programmes to be FDA approved.

The WHO has about 80 drugs on its list whereas the FDA has approved only a handful of products.

The WHO estimates that Indian-made products combining two or three medicines in one pill have brought the cost of first-line AIDS therapy in Africa down to $140-$400 per patient per year compared with brand-name drugs which still cost $400-$600.