Which drug acts as a pharmacokinetic enhancer for certain HIV protease inhibitors?

Cobicistat serves as a pharmacokinetic enhancer for specific HIV protease inhibitors by inhibiting the cytochrome P450 3A (CYP3A) enzyme system. This inhibition leads to increased concentrations of the protease inhibitors in the bloodstream, enhancing their effectiveness while allowing for lower dosages.

By temporarily blocking the metabolism of these drugs, cobicistat improves their pharmacokinetics without providing any direct antiviral activity on its own. This makes it a valuable component in HIV treatment regimens, particularly when combined with protease inhibitors, as it helps maintain optimal therapeutic levels, increasing the chances of a successful treatment outcome.

Other options mentioned do not have this role. For instance, dolutegravir is an integrase strand transfer inhibitor, entecavir is an antiviral primarily used for hepatitis B, and tenofovir is a nucleotide reverse transcriptase inhibitor used to treat HIV and hepatitis B but does not act to enhance the pharmacokinetics of protease inhibitors.