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Phenytoin-Induced Methadone Withdrawal
- THEODORE G. TONG, Pharm.D.;
- SUSAN M. POND, M.B., M.D.;
- MARY JEANNE KREEK, M.D.;
- NARGIS F. JAFFERY, Ph.D.; and
- NEAL L. BENOWITZ, M.D.
Abstract
Methadone-maintained volunteers experienced moderately severe opiate withdrawal symptoms within 3 or 4 days of beginning phenytoin in therapeutic doses. The area under the methadone plasma concentration-time curve decreased while the ratio of the pyrrolidine-to-metabolite excretion in urine to this area increased significantly. This suggests that phenytoin accelerates methadone metabolism. Methadone dosing adjustments should be anticipated when phenytoin is initiated or discontinued in methadone-maintained patients.
Article and Author Information
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▸From the Medical Service, San Francisco General Hospital Medical Center, and the Divisions of Clinical Pharmacy and Clinical Pharmacology and the Drug Dependence Research Center, Langley Porter Institute, University of California, San Francisco, California; and the Rockefeller University, New York, New York.
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Grant support: by grants DA4RG012, DA01696, and DA01138 from the National Institute on Drug Abuse; Clinical Research Center Grants RR00083 and RR00102 from the National Institutes of Health; and Research Scientist Award DA00049 from the Health and Human Services Alcohol, Drug Abuse, and Mental Health Administration-National Institute of Drug Abuse to Dr. Kreek.
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▸Requests for reprints should be addressed to Susan Pond, M.B., M.D.; San Francisco General Hospital, 5H4, 1001 Potrero Avenue; San Francisco, CA 94110.
- © 1981 American College of Physicians
