Sizable reductions in the cost of antiretroviral (ARV) medication in recent years have allowed millions of HIV-positive people in the developing world to access the life-prolonging drugs, but international humanitarian agency Médecins Sans Frontières (MSF) says those gains are facing a serious setback.

Newer and more effective ARV drugs, such as those recommended by the UN World Health Organisation (WHO) in its 2006 treatment guidelines, were much more expensive than older drugs, and would remain so, MSF warned, unless patent barriers were removed, allowing multiple manufacturers to produce them.

According to the 2007 MSF report, Untangling the Web of Price Reductions, released at the International AIDS Society conference in Sydney, Australia, on Wednesday, adopting the WHO's new recommended drug combination would increase the price of first-line treatment by around 500 percent and have a major impact on the budgets of AIDS programmes.

"WHO's new treatment guidelines include a less toxic, tenofovir-based drug [tenofovir disoproxil fumarate] - intended to replace stavudine in the combination of stavudine, lamivudine and nevirapine, used as first-line treatment in much of the developing world - but so far it remains extremely expensive," Karen Day, pharmacist with MSF's Campaign for Access to Essential Medicines, told IRIN/PlusNews.

WHO included tenofovir because of is efficacy, its excellent 'safety profile' and its ease of use: it can be included in once-daily regimens. However, according to MSF, its inclusion would raise the annual cost of treating an adult for one year in a developing country from US$99 to $487.

Governments or individuals who cannot afford tenofovir still have the option of using stavudine, but the WHO notes in its guidelines that the drug has a number of unpleasant side effects, such as lipoatrophy (loss of fat from specific areas of the body, such as the face, arms, legs and buttocks), and a buildup of excess lactic acid that leaves the patient feeling ill.

"It is important to begin planning to move away from ... [stavudine]-containing regimens, so as to avoid or minimise the predictable toxicities associated with this drug," the 2006 WHO guidelines advised.

As growing numbers of people become resistant to first-line ARV regimens, there is a constant need for new second-line drugs to be developed, but these tend to be much more expensive and less widely available.

The prices of older ARV drugs have declined considerably because the lack of patents in developing countries with pharmaceutical manufacturing capacity, such as Thailand, India and Brazil, allowed for competition. But new legislation allows only patent holders to produce medicines that have come onto the market since 2005.

"There is therefore a serious risk that the price crisis seen five years ago, with life-saving ARVs priced out of reach of those in need, is set to return," the MSF report warned.

In terms of the World Trade Organisation's Trade Related Aspects of Intellectual Property Rights (TRIPS) agreements, countries can override drug patents during a public health emergency by issuing a 'compulsory license' to manufacture or import cheaper generic versions.

Thailand has taken advantage of TRIPS to issue compulsory licenses for two AIDS drugs, including the second-line medication, lopinavir, which is likely to fall significantly in price now that it can be imported or produced locally.

In the case of tenofovir, the competition created by multiple manufacturers producing it was the best hope for reducing the price, said MSF's Day. "But we are concerned that, so far, there has been no decision on several pending applications for patents to produce tenofovir in India."

Most HIV-infected people on ARVs in the developing world are taking generic versions of the drugs, manufactured mainly in India. But there has been pressure, most notably from the US, for less developed countries to adopt stronger protection for pharmaceutical companies' intellectual property rights, a move that could jeopardise millions of lives.

The Kenya AIDS NGO Consortium (KANCO), which advocates universal access to ARVS, said steep rises in the price of first-line drugs would endanger the lives of poor Kenyans.

"As it is, the Kenyan government is not getting any additional financing for these drugs, so it would mean far fewer Kenyans are able to access the medication," said Sammy Muraya, KANCO's media liaison. "And the average ... [citizen] cannot afford to spend over 400 [US] dollars a year on ARVs [bought from the private sector]."

He said KANCO would join other groups to lobby pharmaceutical companies to lower their prices, and for the US government to lift its ban on the purchase of non-US approved generic ARVs with money it donates to the President's Emergency Fund for AIDS Relief (PEPFAR), which also limits procurement of the cheapest drugs available for patients in the developing world.

ARV provision in Africa has increased dramatically in recent years: by June 2006 an estimated one million people in sub-Saharan Africa were on ARVs, according to UNAIDS, compared to just 100,000 in 2003.

However, this number still barely skims the surface - about 4.6 million sub-Saharan Africans are thought to be in need of ARVs, while in Asia only 235,000 people are on ARVs, a mere 16 percent of those who need them.