Tamoxifen Allopurinol

Calcium channel blockers and prostaglandins have been used to reduce the nephrotoxic effects of cyclosporin during kidney transplantation.201 Interleukin-2 should be taken cautiously when coadministered with NSAIDs.202 Coadministration of tamoxifen with allopurinol and anticoagulants should be monitored carefully.203... 

A single case report describes allopurinol hepatotoxicity in a man given tamoxifen. 

An elderly man who had been taking allopurinol 300 mg daily for 12 years developed fever and marked increases in his serum levels of lactic dehydrogenase and alkaline phosphatase within a day of starting to take tamoxifen 10 mg twice daily. He rapidly recovered when the allopurinol was stopped. The reasons for the reaction are not understood, but the authors suggested that the increased hepatotoxic effect may have resulted from tamoxifen inhibiting allopurinol metabolism, thereby increasing the serum levels of allopurinol and its metabolite. The general importance of this isolated report is not known. 

Shah KA, Levin J, Rosen N, Greenwald E, Zumoff B. Allopurinol hepatotoxicity potentiated by tamoxifen. NY State J Med ( 9S2) 82, 1745-6. 

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