Bevirimat

Bevirimat is a anti-HIV drug derived from a betulinic acid-like compound, first isolated from Syzygium claviflorum, a Chinese herb. It is believed to inhibit HIV by a novel mechanism, so-called maturation inhibition. It is not currently FDA-approved, but is undergoing clinical trials conducted by the pharmaceutical company Panacos.

Clinical trials
In December 2007, some results of the Phase IIb trial were released. Thomson Financial News reported that, "some patients respond 'very well' to the drug, while another population 'does not respond as well at current dose levels.'" Panacos said it intends to add a group to the study at a higher dosage.

Pharmacokinetics
According to the only currently available study, "the mean terminal elimination half-life of bevirimat ranged from 56.3 to 69.5 hours, and the mean clearance ranged from 173.9 to 185.8 mL/hour."

Mechanism of action
Bevirimat targets the gag polyprotein precursor, the main structural protein responsible for assembly and budding of virion particles. By binding to the gag polyprotein, bevirimat prevents its cleavage by the protease enzyme into functional subunits. Unlike the protease inhibitors, bevirimat binds the gag protein, not the protease enzyme. The resulting virus particles are structurally defective and are incapable of spreading infection around the body. For unknown reasons, protease inhibitor-resistant HIV-1 was hypersensitive to bevirimat in vitro.