Gilead Sciences developing a new HIV drug booster

Gilead Sciences, the US drugs firm that manufactures the biggest-selling HIV drugs in the world, tenofovir, FTC and Atripla recently announced it has initiated human studies of a product that could replace ritonavir as an antiretroviral boosting agent in some fixed-dose combinations.

The drug is currently known as GS 9350. It is is a once-daily, heat-stable compound that can be coformulated with other drugs such as tenofovir and Gilead’s developmental integrase inhibitor elvitegravir (which must currently be boosted with ritonavir to maintain high blood levels).

Human studies with the drug have just begun. 

All currently licensed protease inhibitors apart from nelfinavir (Viracept) are usually boosted with a low dose of ritonavir, and Abbott’s protease inhibitor lopinavir is coformulated with a low dose of ritonavir in the product Kaletra.

Ritonavir, even at low doses can causes increases in triglyceride levels, which must sometimes be controlled with medication or even result in switches to other drugs. It may also play a role in the gastrointestinal problems such as diarrhoea, flatulence and nausea experienced by some people taking protease inhibitors.

Gilead’s aim is to coformulate GS 9350 in a single tablet with its investigational integrase inhibitor elvitegravir, tenofovir and emtricitabine. The company says that preliminary studies have shown this is possible. This would provide the world with a second triple combination pill. Gilead, BMS and Merck recently launched the world’s first triple combination pill; Atripla.