US researchers are claiming a breakthrough in the design of anti-HIV treatments.

A Purdue University team says a new type of protease inhibitor drug, effective against treatment-resistance strains of the virus, will be on the market in a matter of months – and that even more effective variants are set to follow.

Last month, the Food and Drug Administration, granted accelerated approval for the new treatment, Johnson & Johnson’s Prezista (darunavir - formerly known as TMC-114), for use in adults whose HIV infection is not responding to other antiretroviral drugs. Darunavir will be given with low-dose ritonavir, an existing protease inhibitor, in combination with other active anti-HIV agents.

Lead researcher Arun Ghosh, a professor of molecular pharmacology at Purdue said: “We have created a conceptually new class of protease inhibitors to combat drug resistance.”

Eight protease inhibitors are currently on the market and have greatly improved the quality of life for those suffering from HIV. However, side-effects and viral resistance have emerged in many patients.

The Purdue researchers claim that treatment with darunavir has fewer associated side effects because the dose required is significantly less than those for existing protease inhibitors. The molecule also is smaller than current protease inhibitors and is more easily absorbed and tolerated by the body, according to research results.

"I think that this drug will have a sizeable impact on the current therapy for AIDS and HIV infection," said Dr Hiroaki Mitsuya, the principal investigator of the Experimental Retrovirology Section at the National Cancer Institute, who collaborated with Dr Ghosh in the drug’s development. In Phase III clinical trials, the majority of patients receiving darunavir showed higher CD4 counts with relatively few side effects. Many were treated for a year or more without showing significant resistance to the drug.

Details of the research will appear in the August 24 issue of the Journal of Medicinal Chemistry.