TOLTERODINE Drug Interactions: What You Need to Know

INTERACTIONS

• 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 <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.1) ]</span> . 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 <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.3) ]</span> .

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 <span class="opacity-50 text-xs">[see Dosage and Administration (2.2) and Clinical Pharmacology (12.3) ]</span> .

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 <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.3) ]</span> .

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 <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.3) ]</span> .

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.

Drug Interactions

Potent CYP2D6 Inhibitors Fluoxetine is a selective serotonin reuptake inhibitor and a potent inhibitor of CYP2D6 activity. In a study to assess the effect of fluoxetine on the pharmacokinetics of tolterodine immediate release and its metabolites, it was observed that fluoxetine significantly inhibited the metabolism of tolterodine immediate release in 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). Fluoxetine thus alters the pharmacokinetics in patients who would otherwise be CYP2D6 extensive metabolizers of tolterodine immediate release to resemble the pharmacokinetic profile in poor metabolizers. The sums of unbound serum concentrations of tolterodine immediate release and 5-HMT are only 25% higher during the interaction. No dose adjustment is required when tolterodine and fluoxetine are co-administered. Potent CYP3A4 Inhibitors The effect of a 200 mg daily dose of ketoconazole on the pharmacokinetics of tolterodine immediate release was studied in 8 healthy volunteers, all of whom were CYP2D6 poor metabolizers. In the presence of ketoconazole, the mean C max and AUC of tolterodine increased by 2- and 2.5-fold, respectively. Based on these findings, other potent CYP3A4 inhibitors may also lead to increases of tolterodine plasma concentrations. For patients receiving ketoconazole or other potent CYP3A4 inhibitors such as itraconazole, miconazole, clarithromycin, ritonavir, the recommended dose of tolterodine tartrate extended-release capsules is 2 mg daily [see Dosage and Administration (2.3) ] . Warfarin In healthy volunteers, coadministration of tolterodine immediate release 4 mg (2 mg bid) for 7 days and a single dose of warfarin 25 mg on day 4 had no effect on prothrombin time, Factor VII suppression, or on the pharmacokinetics of warfarin.

Oral Contraceptives

Tolterodine immediate release 4 mg (2 mg bid) had no effect on the pharmacokinetics of an oral contraceptive (ethinyl estradiol 30 µg/levonorgestrel 150 µg) as evidenced by the monitoring of ethinyl estradiol and levonorgestrel over a 2-month period in healthy female volunteers.

Diuretics

Coadministration of tolterodine immediate release up to 8 mg (4 mg bid) for up to 12 weeks with diuretic agents, such as indapamide, hydrochlorothiazide, triamterene, bendroflumethiazide, chlorothiazide, methylchlorothiazide, or furosemide, did not cause any adverse electrocardiographic (ECG) effects. Effect of Tolterodine on Other Drugs Metabolized by Cytochrome P450 Enzymes Tolterodine immediate release does not cause clinically significant interactions with other drugs metabolized by the major drug-metabolizing CYP enzymes. 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. In vitro data show that tolterodine immediate release is a competitive inhibitor of CYP2D6 at high concentrations (Ki 1.05 µM), while tolterodine immediate release as well as the 5-HMT are devoid of any significant inhibitory potential regarding the other isoenzymes.

Tolterodine tartrate extended-release capsules are contraindicated in patients with urinary retention, gastric retention, or uncontrolled narrow-angle glaucoma. Tolterodine tartrate extended-release capsules are also contraindicated in patients with known hypersensitivity to the drug or its ingredients, or to fesoterodine fumarate extended-release tablets which, like tolterodine tartrate extended-release capsules, are metabolized to 5-hydroxymethyl tolterodine. ( 4 ) Tolterodine tartrate extended-release capsules are contraindicated in patients with urinary retention, gastric retention, or uncontrolled narrow-angle glaucoma. Tolterodine tartrate extended-release capsules are also contraindicated in patients with known hypersensitivity to the drug or its ingredients, or to fesoterodine fumarate extended-release tablets which, like tolterodine tartrate extended-release capsules, are metabolized to 5-hydroxymethyl tolterodine [ see WARNINGS AND PRECAUTIONS ( 5.2 ), ( 5.3 ), ( 5.4 ) ] .

AND PRECAUTIONS

• Anaphylaxis and angioedema requiring hospitalization and emergency medical treatment have occurred with the first or subsequent doses of tolterodine tartrate extended-release capsules. ( 5.1 )
• Urinary Retention: use caution in patients with clinically significant bladder outflow obstruction because of the risk of urinary retention. ( 5.2 )
• Gastrointestinal Disorders: use caution in patients with gastrointestinal obstructive disorders or decreased gastrointestinal motility because of the risk of gastric retention. ( 5.3 )
• Controlled Narrow-Angle Glaucoma: use caution in patients being treated for narrow-angle glaucoma. ( 5.4 )
• Central Nervous System Effects: Somnolence has been reported with tolterodine tartrate extended-release capsules. Advise patients not to drive or operate heavy machinery until they know how tolterodine tartrate extended-release capsules affect them. ( 5.5 )
• Myasthenia Gravis: use caution in patients with myasthenia gravis. ( 5.8 )
• QT Prolongation : consider observations from the thorough QT study in clinical decisions to prescribe tolterodine tartrate extended-release capsules to patients with a known history of QT prolongation or to patients who are taking Class IA (e.g., quinidine, procainamide) or Class III (e.g., amiodarone, sotalol) antiarrhythmic medications. ( 5.9 )

5.1 Angioedema Anaphylaxis and angioedema requiring hospitalization and emergency medical treatment have occurred with the first or subsequent doses of tolterodine tartrate extended-release capsules. In the event of difficulty in breathing, upper airway obstruction, or fall in blood pressure, tolterodine tartrate extended-release capsules should be discontinued and appropriate therapy promptly provided.

5.2 Urinary Retention Administer tolterodine tartrate extended-release capsules with caution to patients with clinically significant bladder outflow obstruction because of the risk of urinary retention [ see CONTRAINDICATIONS ( 4 ) ].

5.3 Gastrointestinal Disorders Administer tolterodine tartrate extended-release capsules with caution in patients with gastrointestinal obstructive disorders because of the risk of gastric retention. Tolterodine tartrate extended-release capsules, like other antimuscarinic drugs, may decrease gastrointestinal motility and should be used with caution in patients with conditions associated with decreased gastrointestinal motility (e.g., intestinal atony) [ see CONTRAINDICATIONS ( 4 ) ].

5.4 Controlled Narrow-Angle Glaucoma Administer tolterodine tartrate extended-release capsules with caution in patients being treated for narrow-angle glaucoma [ see CONTRAINDICATIONS ( 4 ) ].

5.5 Central Nervous System Effects Tolterodine tartrate extended-release capsules are associated with anticholinergic central nervous system (CNS) effects <span class="opacity-50 text-xs">[see Adverse Reactions ( 6.2 )]</span> including dizziness and somnolence <span class="opacity-50 text-xs">[see Adverse Reactions ( 6.1 )]</span> . Patients should be monitored for signs of anticholinergic CNS effects, particularly after beginning treatment or increasing the dose. Advise patients not to drive or operate heavy machinery until the drug&apos;s effects have been determined. If a patient experiences anticholinergic CNS effects, dose reduction or drug discontinuation should be considered.

5.6 Hepatic Impairment The clearance of orally administered tolterodine immediate release was substantially lower in cirrhotic patients than in the healthy volunteers. For patients with mild to moderate hepatic impairment (Child-Pugh Class A or B), the recommended dose for tolterodine tartrate extended-release capsules is 2 mg once daily. Tolterodine tartrate extended-release capsules are not recommended for use in patients with severe hepatic impairment (Child-Pugh Class C) [ see DOSAGE AND ADMINISTRATION ( 2.2 ) and USE IN SPECIFIC POPULATIONS ( 8.6 ) ] .

5.7 Renal Impairment Renal impairment can significantly alter the disposition of tolterodine and its metabolites. The dose of tolterodine tartrate extended-release capsules should be reduced to 2 mg once daily in patients with severe renal impairment (CCr: 10 to 30 mL/min). Patients with CCr&lt;10 mL/min have not been studied and use of tolterodine tartrate extended-release capsules in this population is not recommended [ see DOSAGE AND ADMINISTRATION (2.2) and USE IN SPECIFIC POPULATIONS ( 8.7 ) ].

5.8 Myasthenia Gravis Administer tolterodine tartrate extended-release capsules with caution in patients with myasthenia gravis, a disease characterized by decreased cholinergic activity at the neuromuscular junction.

5.9 Use in Patients with Congenital or Acquired QT Prolongation In a study of the effect of tolterodine immediate release tablets on the QT interval [ see CLINICAL PHARMACOLOGY ( 12.2 ) ], the effect on the QT interval appeared greater for 8 mg/day (two times the therapeutic dose) compared to 4 mg/day and was more pronounced in CYP2D6 poor metabolizers (PM) than extensive metabolizers (EMs). The effect of tolterodine 8 mg/day was not as large as that observed after four days of therapeutic dosing with the active control moxifloxacin. However, the confidence intervals overlapped. These observations should be considered in clinical decisions to prescribe tolterodine tartrate extended-release capsules to patients with a known history of QT prolongation or to patients who are taking Class IA (e.g., quinidine, procainamide) or Class III (e.g., amiodarone, sotalol) antiarrhythmic medications. There has been no association of Torsade de Pointes in the international post-marketing experience with tolterodine tartrate immediate release tablets or tolterodine tartrate extended-release capsules.