Tolterodine Fluoxetine

The increases in tolterodine levels were not considered to be clinically relevant, and no routine dosage adjustment of tolterodine dosage was considered necessary when given with duloxetine. Consider also Urinary antimuscarinics Tolterodine + Fluoxetine , p.l290. 

Tolterodine undergoes hepatic metabolism involving CYP450 2D6 and 3A4 isoenzymes. Therefore, elimination can be impaired by CYP450 3A4 inhibitors including fluoxetine, sertraline, fluvoxamine, macrolide antibiotics, imidazoles, and grapefruit juice. 

Fluoxetine Fluoxetine is a potent inhibitor of cytochrome P450 2D6 activity. No dose adjustment is required when tolterodine and fluoxetine are coadministered. 

Although fluoxetine can markedly inhibit the metabolism of tolterodine in some patients this is unlikely to cause a clinically important increase in the effects of tolterodine. 

BrynneN, Svanstrfim C, Aberg-Wistedt A, HallenB, BertlissonL. Fluoxetine inhibits the me-tabolism of tolterodine—pharmacokinetic implications and proposed clinical relevance. BrJ Clin Pharmacol (1999) 48, 553-63. 

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