The opposition, represented by the lawyers' collective hiv/aids unit is based on technical and health grounds.
''We are opposing the patenting of combivir as it is not a new invention but simply the combination of two existing drugs. The granting of such a patent risks increases the cost of anti-retroviral treatment for many people living with hiv/aids thereby further increasing the burden on developing countries already struggling to treat patients,'' said K K Abraham, president of Inp+.
Combivir is a widely used fixed dose combination and is used extensively in projects run by international aid organisation medicines sans frontiers (msf). Almost all the combivir used by msf is generic. India, Burkina Faso, Mongolia, Central African Republic, Malawi, Peru, the Republic of Kyrgizstan, Cambodia, Ukraine are other countries identified by the global fund as using generic combivir, the two organisations said.
''Patents create monopolies on drug manufacture and prevent the production of such affordable generic alternatives,'' they said.
The availability of affordable quality generic versions of combivir and other anti-retroviral medicines has allowed developing countries to put more people on treatment and thus extend their lives, they added.
In India alone, there are 5.1 million people living with hiv/aids, many of whom receive generic drugs under the national hiv/aids treatment programme.
Decisions made by Indian patent offices are a question of life or death for people living with hiv/aids, who rely on the availability of affordable aids drugs and other essential medicines made by Indian generic manufacturers, the members of the two organisations added.
Last year, India changed its patent law to comply with the World Trade Organisation's trips agreement that governs trade agreements and intellectual property rights. Three weeks ago, India granted its first ever patent on a drug, Hepatitis C produced by Roche. Public interest groups are deeply concerned this will set a precedent leading to the patenting of other essential medicines including anti-retrovirals, sources said.
Besides combivir there are other patent applications of essential medicines waiting to be approved or rejected, including other anti-retrovirals and drugs for treating mental illness, tuberculosis and opportunistic infections, they further pointed out.
It was claimed that the new Indian patent law allows oppositions to a patent application before it is granted. Indian cancer patients and generic drug manufacturers recently opposed a novartis patent application for gleevec, an anti-cancer drug, on the grounds that the application claimed a new form of an old drug.
The patent was subsequently rejected by the patent office.
Petitioners are now demanding that the combivir patent application be rejected on similar grounds.