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June 14, 2000

Effect of Ritonavir on Saquinavir Metabolism—Reply

Author Affiliations

Phil B.FontanarosaMD, Deputy EditorIndividualAuthorStephen J.LurieMD, PhD, Contributing EditorIndividualAuthor

JAMA. 2000;283(22):2936-2937. doi:10.1001/jama.283.22.2931

In Reply: We agree that there should be attention to dose adjustments for drug combinations (including saquinavir SGF and ritonavir) for which there are substantial effects on the metabolism of one drug by the other. The data in our table are accurate as presented and are as cited in the current (2000) package insert for saquinavir SGF.1 However, the more recent data described by Dr Buss2 using a higher dose of saquinavir SGF (800 mg, twice daily) in combination with ritonavir, 200 or 400 mg, twice daily, found increases in AUCs for saquinavir SGF of 1589% and 2158%, respectively. Both sets of data are accurate but represent different dosing regimens of the saquinavir SGF and ritonavir combination. Table 2 of our article provides some examples of possible dose changes in these situations.