Reyataz (atazanavir) can now be safely used in some circumstances with stomach-acid-reducing proton-pump inhibitors (PPIs), a drug class formerly prohibited with Reyataz, according to recent update to the protease inhibitor’s packaging information authorized by the U.S. Food and Drug Administration. However, PPIs and other heartburn and gastric reflux (GERD) medications still need to be used carefully if they are combined with Reyataz—and not at all in some cases.

Because Reyataz requires acid in the stomach to be broken down and absorbed into the bloodstream, there have long been concerns about using acid reflux medications like antacids and the more powerful H2-receptor antagonists (Zantac, Tagemet and Pepcid, for example) and PPIs (Propulsid, Nexium, Prevacid, Prilosec and Protonix, for example). Since the approval of Reyataz in 2003, there have been warnings against using it with PPIs. H2-receptor antagonists could be used, but taken either 12 hours before or after Reyataz.

While the revised packaging information continues to warn against treatment-experienced patients using PPIs with Reyataz, combining these drugs is now possible for people who are on their first HIV treatment regimen, also known as treatment-naive patients. Treatment-naive patients who wish to use a PPI must be taking Reyataz at a dose of 300mg combined with a 100mg dose of Norvir (ritonavir) and food. They must take the PPI 12 hours before taking Reyataz, and the PPI dose must not exceed the equivalent of 20mg of Prilosec.

The new prescribing information also offers new guidelines for combining Reyataz with H2-receptor antagonists. Treatment-naive patients who wish to take an H2-receptor antagonist must be taking Reyataz at a dose of 300mg combined with a 100mg dose of Norvir along with food, and they should take Reyataz at the same time as the H2-receptor antagonist or 10 hours after. This means that if a person takes Pepcid at 8:00 a.m., they should either take Reyataz at the same time, or wait to take it until at least 6:00 p.m. Also, the dose of the H2-receptor antagonist should not exceed the equivalent of 40mg of Pepcid.

Treatment-experienced patients should follow the same guidelines for combining Reyataz with an H2-receptor antagonist, with two exceptions. First, the dose of the H2-receptor antagonist should not exceed the equivalent of 20mg of Pepcid. Second, if they are taking tenofovir (found in Viread, Truvada and Atripla) along with an H2-receptor antagonist, they should increase their dose of Reyataz to 400mg.

Usage recommendations for antacids—such as Tums or Pepto-Bismol—remains the same: Take them two hours before or after Reyataz.