Drugs that increase gastric pH are predicted to reduce the
plasma levels of
atazanavir, and possibly also
amprenavir. Tipranavir levels are decreased by up to 30% by
antacids (containing aluminium/magnesium hydroxide).
The manufacturers of
atazanavir recommend that it should be given 2 hours before or one hour after buffered medicinal products. This would include didanosine buffered tablets and
antacids. The manufacturer of
amprenavir recommends that it should not be given within one hour of antacids, and the manufacturer of
tipranavir recommends that it should not be given within 2 hours of
antacids.