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Drug-Drug Interactions: Aluminum- and Magnesium-Containing Antacids Not Recommended with Raltegravir
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I have previously discussed the interactions between polyvalent cations (eg, aluminum, calcium, iron, and magnesium) and the integrase inhibitors ( The package label of each integrase inhibitor provides specific recommendations about the concurrent use of cation-containing agents.

Recent data show antacids containing aluminum and magnesium on substantially lower plasma raltegravir levels even when the antacid is taken up to 6 hours before or after the raltegravir: The Cmin of raltegravir is reduced 63% if taken at the same time as an Al-Mg hydroxide antacid, about 60% if the antacid is given 2 or 4 hours before or 2 or 4 hours after raltegravir, and 50% if it is given 6 hours before or 6 hours after raltegravir. AUC and Cmax values also were depressed.

Based on these data, the prescribing information for raltegravir has been changed to say that either coadministration or staggered administration of raltegravir and aluminum and/or magnesium-hydroxide antacids is not recommended.

Similar PK studies of the other integrase inhibitors with these antacids in which dosing is separated by 4 to 6 or more hours have not been reported, but pending these it would seem wise to avoid antacids that contain aluminum or magnesium in patients taking any of the integrase inhibitors.