Drug Interaction Report

MONITOR: Theoretical concerns exist that isotretinoin and phenytoin may have additive effects on bone loss. Decreased bone mineral density (osteomalacia, osteopenia, osteoporosis) and bone fractures have been reported with chronic use of either agent alone. However, no formal clinical trials have been conducted to evaluate whether there is an interactive effect on bone loss during coadministration. Isotretinoin did not alter the pharmacokinetics of phenytoin in a study of seven healthy volunteers.

MANAGEMENT: Caution is advised when isotretinoin and phenytoin are used together, particularly in patients with a history of osteomalacia, osteoporosis, or other disorders of bone metabolism. Bone-related laboratory and radiological tests should be considered.

GENERALLY AVOID: The combined use of ethanol and isotretinoin may result in a disulfiram-like reaction. The mechanism has not been established.

MANAGEMENT: Alcohol consumption should be avoided during isotretinoin therapy.