People currently taking the protease inhibitor (PI) Lexiva (fosamprenavir) in conjunction with the PI Norvir (ritonavir) may now lower their Norvir dose from 200 mg per day to 100 mg, according to the Food and Drug Administration (FDA).

Norvir is commonly used to “boost” blood levels of Lexiva and many other HIV drugs. Until today’s FDA approval, the recommended once-daily dose of the Norvir-boosted Lexiva combination was 1,400 mg of Lexiva with 200 mg of Norvir for people new to PI therapy. Research found, however, that Lexiva in combination with a lower dose of Norvir, 100 mg, was just as effective and resulted in fewer side effects.

The newly approved dose of Norvir with Lexiva only applies to people who have not previously taken a PI and who wish to use Lexiva once a day. The recommended dosing in people who have used other PIs in the past remains 700 mg of Lexiva plus 100 mg of Norvir twice daily.