New classes of antiretrovirals aren’t gushing out of the pipeline today, but you can spot plenty of old stand-bys in new get-ups. The latest makeover: Agouron’s buff, 625-mg update of its protease inhibitor, nelfinavir (Viracept). FDA-approved in April, it slashes the 250-mg version’s pill count—from 10 to four—with the same twice-daily dosing.

Fewer pills can mean better adherence, and that’s grand. But some pipeline insiders worry that the new version may cause even more diarrhea than its bowel-loosening predecessor because of its greater bioavailability (how much of, and how fast, your body can process a substance). Richard Ogden, Agouron’s senior director of scientific development, told POZ their research shows “no increase in the frequency of diarrhea” at higher doses.

The new model joins the old on shelves this fall, and Ogden says many patients will be advised to switch. Only HIVers who do so will be able to tell if the new pill is the charm—or the Charmin.