Tolterodine extended-release

Potent CYP3A4 Inhibitors: Coadministration may increase systemic exposure to tolterodine tartrate extended-release capsules. Reduce tolterodine tartrate extended-release capsules dose to 2 mg once daily. ( 7.2 ) Other Anticholinergics (antimuscarinics): Concomitant use with other anticholinergic agents may increase the frequency and/or severity of dry mouth, constipation, blurred vision, and other anticholinergic pharmacological effects. (7.6 )

7.1 Potent CYP2D6 Inhibitors Fluoxetine, a potent inhibitor of CYP2D6 activity, significantly inhibited the metabolism of tolterodine immediate release in CYP2D6 extensive metabolizers, resulting in a 4.8-fold increase in tolterodine AUC. There was a 52% decrease in C max and a 20% decrease in AUC of 5-hydroxymethyl tolterodine (5-HMT), the pharmacologically active metabolite of tolterodine [ see CLINICAL PHARMACOLOGY ( 12.1 ) ]. The sums of unbound serum concentrations of tolterodine and 5-HMT are only 25% higher during the interaction. No dose adjustment is required when tolterodine and fluoxetine are co-administered [ see CLINICAL PHARMACOLOGY (12.3) ] .

7.2 Potent CYP3A4 Inhibitors Ketoconazole (200 mg daily), a potent CYP3A4 inhibitor, increased the mean C max and AUC of tolterodine by 2- and 2.5-fold, respectively, in CYP2D6 poor metabolizers. For patients receiving ketoconazole or other potent CYP3A4 inhibitors such as itraconazole, clarithromycin, or ritonavir, the recommended dose of tolterodine tartrate extended-release capsules is 2 mg once daily [ see DOSAGE AND ADMINISTRATION ( 2.2) and CLINICAL PHARMACOLOGY ( 12.3) ].

7.3 Other Interactions No clinically relevant interactions have been observed when tolterodine was co-administered with warfarin, with a combined oral contraceptive drug containing ethinyl estradiol and levonorgestrel, or with diuretics [ see CLINICAL PHARMACOLOGY ( 12.3 ) ] .

7.4 Other Drugs Metabolized by Cytochrome P450 Isoenzymes In vivo drug-interaction data show that tolterodine immediate release does not result in clinically relevant inhibition of CYP1A2, 2D6, 2C9, 2C19, or 3A4 as evidenced by lack of influence on the marker drugs caffeine, debrisoquine, S-warfarin, and omeprazole [ see CLINICAL PHARMACOLOGY ( 12.3 ) ] .

7.5 Drug-Laboratory-Test Interactions Interactions between tolterodine and laboratory tests have not been studied.

7.6 Other Anticholinergics The concomitant use of tolterodine tartrate extended-release capsules with other anticholinergic (antimuscarinic) agents may increase the frequency and/or severity of dry mouth, constipation, blurred vision, somnolence, and other anticholinergic pharmacological effects.

8.1 Pregnancy Risk Summary There are no available data with tolterodine tartrate extended-release capsules use in pregnant women to inform drug-associated risks. In animal reproduction studies, oral administration of tolterodine and its 5-HMT metabolite to pregnant mice during organogenesis did not produce adverse developmental outcomes at doses approximately 9 to 12 times the clinical exposure at a dose of 20 mg/kg/day; however, higher doses produced adverse developmental outcomes (see Data) . In the U.S. general population, the estimated background rate of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Data Animal Data No anomalies or malformations were observed after oral administration of tolterodine to pregnant mice during organogenesis at approximately 9 to 12 times the clinical exposure to the pharmacologically active components of tolterodine tartrate extended-release capsules (based on the AUC of tolterodine and its 5-HMT metabolite at a dose of 20 mg/kg/day). At 14 to 18 times the clinical exposure (doses of 30 to 40 mg/kg/day) in mice, tolterodine was embryo-lethal, caused reduced fetal weight, and increased the incidence of fetal abnormalities (cleft palate, digital abnormalities, intra-abdominal hemorrhage, and various skeletal abnormalities, primarily reduced ossification).

Pregnant rabbits administered tolterodine subcutaneously at about 0.3 to 2.5 times the clinical exposure (dose of 0.8 mg/kg/day) did not show any embryotoxicity or teratogenicity.