Mumbai: British drug maker GlaxoSmithKline Plc. has withdrawn its Indian patent application for its antiretroviral combination drug Trizivir, the second time in a year that it has pulled such a request.

Last year, the company had withdrawn a patent application for its popular anti-HIV combination drug Combivir following protests from health activists and non-government organizations.

Trizivir is a fixed-dose combination tablet containing three drugs, lamivudine, zidovudine and abacavir sulfate. Glaxo had received the US Food and Drug Administration approval for this first three-drug combination tablet for HIV treatment in 2005.

The firm, which currently holds patent right for this combination drug internationally, had applied for a patent in India in 2000 through the Patent Cooperation Treaty, an international patent law treaty, at the Kolkata patent office.

In 2006, Indian drug maker Cipla Ltd filed a pre-grant opposition against Glaxo application. Even as hearings have been going on, the Kolkata patent office informed Cipla on Tuesday that Glaxo has voluntarily withdrawn its application.

A Glaxo spokesperson would only say that “the company’s move is in public interest and is part of its policy of routine review of patent applications.”

The move is in sharp contrast to Novartis AG, which has fought a bitter legal battle over the rejected patent for its Glivec drug.

Cipla had opposed the Glaxo patent on the grounds that all the three drugs contained in this combination tablet are already known individually, so it does not qualify for a patent. “Under Section 3 (d) of the Indian Patents Act, combinations of known substances are not inventions and hence not patentable,” notes Cipla managing director Amar Lulla. “All the three drugs i.e. abacavir, lamivudine and zidovudine are known substances.”

Patented drugs for HIV treatment worldwide cost around $10,000-12,000 for a course, though many major drug companies, including Glaxo, have free-drug supply programmes to support AIDS patients in poor countries.

Cipla had triggered a significant price reduction in the world AIDS drug market by introducing cheap generic versions of these high cost drugs at one tenth of the price in HIV-prevalent countries, especially in Africa and some South Asian countries.

Lulla did say that Cipla had not “launched this formulation (the Glaxo drug combination)... as yet.”

Glaxo has been a market leader in the anti-HIV drug market worldwide with its single drug and combination brands. However, with the advent and widespread use of combined antiretroviral therapy over the past few years, Glaxo and other drug companies have created fixed-dose combinations, or FDCs, of AIDS drugs to provide added convenience for the patients by combining two or more single medications into one pill.

Such combined formulations have also become an innovative way for the drug industry to extend the life of patent protection for certain drugs.

In Glaxo’s case, it created Combivir, the two-drug combination consisting of its brands AZT, or zidovudine, and Epivir, or lamivudine, which was convenient for patients and also quickly became the most widely used and best selling AIDS therapy in the world.

As a result, Glaxo’s Combivir drove down demand for older, single medications. By some estimates, Glaxo sold only about $79 million of AZT in 2004, compared with 2004 combined sales of $1.4 billion for Combivir and Trizivir.

ch.unni@livemint.com