Hydroxychloroquine Rifampicin

A woman with discoid lupus, controlled by hydroxychloroquine, rapidly relapsed when rifampicin was started. Disease control was regained when the hydroxychloroquine dosage was doubled. 

This seems to be the first and only report of this interaction, but what happened is consistent with the way rifampicin interacts with many other drugs. If rifampicin is added to hydroxychloroquine, the outcome should be well monitored. Be alert for the need to increase the hydroxychloroquine dosage. 

Harvey CJ, Bateman NT, Lloyd ME, Hughes GRV. Influence of rifampicin on hydroxychloroquine. Clin Exp Rheumatol ( 995) 13, 536. 

Drug interactions The extent to which vitamin D supplementation alters drug effectiveness and toxicity in humans has been systematically reviewed. Bile acid sequestrants and lipase inhibitors were found to inhibit the absorption of vitamin D from the gut. Statins, rifampicin, isoniazid, hydroxychloroquine, antiepileptics, corticosteroids, immimo-suppressive and chemotherapeutic agents, antiretroviral drugs and H2 receptor antagonists interfered with vitamin D metabolism. The interaction between vitamin D and thiazide diuretics could result in hypercalcaetnia. Vitamin D supplementation decreases concentrations of atorvastatin, and could cause hypercalcaetnia in elderly individuals or tixose with compromised renal function or hyperparathyroidism [84 ]. 

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