描述
Fluconazole inhibits CYP3A4-mediated tamsulosin metabolism, substantially increasing tamsulosin exposure and the risk of hypotension and syncope.
机制
CYP3A4 is a major route of tamsulosin metabolism; potent inhibition by fluconazole increases tamsulosin AUC significantly, amplifying alpha-1 adrenoceptor blockade-mediated vasodilation.
临床意义
Controlled drug interaction studies with strong CYP3A4 inhibitors show clinically significant tamsulosin concentration increases; symptomatic hypotension and dizziness are the primary safety concerns.
处理措施
Advise patient on orthostatic hypotension precautions when fluconazole is prescribed concurrently; consider whether the antifungal indication can be treated with a less potent CYP3A4 inhibitor if tamsulosin is critical.