Tolterodine Tartrate Extended Release 2 mg Capsule, Extended Release, 500-count — NDC 59762-0047-3 (Billing 59762-0047-03)

12 CLINICAL PHARMACOLOGY

12.1Mechanism of Action Tolterodine acts as a competitive antagonist of acetylcholine at postganglionic muscarinic receptors. Both urinary bladder contraction and salivation are mediated via cholinergic muscarinic receptors. After oral administration, tolterodine is metabolized in the liver, resulting in the formation of 5-hydroxymethyl tolterodine (5-HMT), the major pharmacologically active metabolite.

5-HMT, which exhibits an antimuscarinic activity similar to that of tolterodine, contributes significantly to the therapeutic effect. Both tolterodine and 5-HMT exhibit a high specificity for muscarinic receptors, since both show negligible activity or affinity for other neurotransmitter receptors and other potential cellular targets, such as calcium channels.

12.2Pharmacodynamics Tolterodine has a pronounced effect on bladder function. Effects on urodynamic parameters before and 1 and 5 hours after a single 6.4 mg dose of tolterodine immediate release were determined in healthy volunteers. The main effects of tolterodine at 1 and 5 hours were an increase in residual urine, reflecting an incomplete emptying of the bladder, and a decrease in detrusor pressure.

These findings are consistent with an antimuscarinic action on the lower urinary tract. Cardiac Electrophysiology The effect of 2 mg BID and 4 mg BID of tolterodine immediate release tablets on the QT interval was evaluated in a 4-way crossover, double-blind, placebo- and active-controlled (moxifloxacin 400 mg QD) study in healthy male (N=25) and female (N=23) volunteers aged 18–55 years. Study subjects [approximately equal representation of CYP2D6 extensive metabolizers (EMs) and poor metabolizers (PMs)] completed sequential 4-day periods of dosing with moxifloxacin 400 mg QD, tolterodine 2 mg BID, tolterodine 4 mg BID, and placebo.

The 4 mg BID dose of tolterodine immediate release (two times the highest recommended dose) was chosen because this dose results in tolterodine exposure similar to that observed upon coadministration of tolterodine 2 mg BID with potent CYP3A4 inhibitors in patients who are CYP2D6 poor metabolizers [see Drug Interactions (7.2) ] . QT interval was measured over a 12-hour period following dosing, including the time of peak plasma concentration (T max ) of tolterodine and at steady state (Day 4 of dosing). Table 2 summarizes the mean change from baseline to steady state in corrected QT interval (QT c ) relative to placebo at the time of peak tolterodine (1 hour) and moxifloxacin (2 hour) concentrations.

Both Fridericia’s (QT c F) and a population-specific (QT c P) method were used to correct QT interval for heart rate. No single QT correction method is known to be more valid than others. QT interval was measured manually and by machine, and data from both are presented.

The mean increase of heart rate associated with a 4 mg/day dose of tolterodine in this study was 2.0 beats/minute and 6.3 beats/minute with 8 mg/day tolterodine. The change in heart rate with moxifloxacin was 0.5 beats/minute. Table 2.

Mean (CI) change in QTc from baseline to steady state (Day 4 of dosing) Drug/Dose N QT c F (msec) (manual) QT c F (msec) (machine) QT c P (msec) (manual) QT c P (msec) (machine) Tolterodine 2 mg BID At T max of 1 hr; 95% Confidence Interval. 48 5.01 (0.28, 9.74) 1.16 (-2.99, 5.30) 4.45 (-0.37, 9.26) 2.00 (-1.81, 5.81) Tolterodine 4 mg BID 48 11.84 (7.11, 16.58) 5.63 (1.48, 9.77) 10.31 (5.49, 15.12) 8.34 (4.53, 12.15) Moxifloxacin 400 mg QD At T max of 2 hr; 90% Confidence Interval. 45

19.26The effect on QT interval with 4 days of moxifloxacin dosing in this QT trial may be greater than typically observed in QT trials of other drugs. (15.49, 23.03) 8.90 (4.77, 13.03) 19.10 (15.32, 22.89) 9.29 (5.34, 13.24) The reason for the difference between machine and manual read of QT interval is unclear. The QT effect of tolterodine immediate release tablets appeared greater for 8 mg/day (two times the therapeutic dose) compared to 4… [Excerpted — this section continues on DailyMed.]

12.1Mechanism of Action Tolterodine acts as a competitive antagonist of acetylcholine at postganglionic muscarinic receptors. Both urinary bladder contraction and salivation are mediated via cholinergic muscarinic receptors. After oral administration, tolterodine is metabolized in the liver, resulting in the formation of 5-hydroxymethyl tolterodine (5-HMT), the major pharmacologically active metabolite.

5-HMT, which exhibits an antimuscarinic activity similar to that of tolterodine, contributes significantly to the therapeutic effect. Both tolterodine and 5-HMT exhibit a high specificity for muscarinic receptors, since both show negligible activity or affinity for other neurotransmitter receptors and other potential cellular targets, such as calcium channels.

12.3Pharmacokinetics Absorption In a study with 14 C-tolterodine solution in healthy volunteers who received a 5 mg oral dose, at least 77% of the radiolabeled dose was absorbed. C max and area under the concentration-time curve (AUC) determined after dosage of tolterodine immediate release are dose-proportional over the range of 1 to 4 mg. Based on the sum of unbound serum concentrations of tolterodine and 5-HMT (“active moiety”), the AUC of tolterodine extended release 4 mg daily is equivalent to tolterodine immediate release 4 mg (2 mg bid).

C max and C min levels of tolterodine extended release are about 75% and 150% of tolterodine immediate release, respectively. Maximum serum concentrations of tolterodine extended release are observed 2 to 6 hours after dose administration. Effect of Food There is no effect of food on the pharmacokinetics of tolterodine extended release.

Distribution Tolterodine is highly bound to plasma proteins, primarily α 1 -acid glycoprotein. Unbound concentrations of tolterodine average 3.7% ± 0.13% over the concentration range achieved in clinical studies. 5-HMT is not extensively protein bound, with unbound fraction concentrations averaging 36% ± 4.0%.

The blood to serum ratio of tolterodine and 5-HMT averages 0.6 and 0.8, respectively, indicating that these compounds do not distribute extensively into erythrocytes. The volume of distribution of tolterodine following administration of a 1.28 mg intravenous dose is 113 ±

26.7L. Metabolism Tolterodine is extensively metabolized by the liver following oral dosing. The primary metabolic route involves the oxidation of the 5-methyl group and is mediated by the cytochrome P450 2D6 (CYP2D6) and leads to the formation of a pharmacologically active metabolite, 5-HMT.

Further metabolism leads to formation of the 5-carboxylic acid and N -dealkylated 5-carboxylic acid metabolites, which account for 51% ± 14% and 29% ± 6.3% of the metabolites recovered in the urine, respectively. Variability in Metabolism A subset of individuals (approximately 7% of Caucasians and approximately 2% of African Americans) are poor metabolizers for CYP2D6, the enzyme responsible for the formation of 5-HMT from tolterodine. The identified pathway of metabolism for these individuals (“poor metabolizers”) is dealkylation via cytochrome P450 3A4 (CYP3A4) to N -dealkylated tolterodine.

The remainder of the population is referred to as “extensive metabolizers.” Pharmacokinetic studies revealed that tolterodine is metabolized at a slower rate in poor metabolizers than in extensive metabolizers; this results in significantly higher serum concentrations of tolterodine and in negligible concentrations of 5-HMT. Excretion Following administration of a 5 mg oral dose of 14 C-tolterodine solution to healthy volunteers, 77% of radioactivity was recovered in urine and 17% was recovered in feces in 7 days. Less than 1% (< 2.5% in poor metabolizers) of the dose was recovered as intact tolterodine, and 5% to 14% (<1% in poor metabolizers) was recovered as 5-HMT.

A summary of mean (± standard deviation) pharmacokinetic parameters of tolterodine extended release and 5-HMT in extensive (EM) and poor (PM) metabolizers is provided in Table 3. These data were obtained following single and multiple doses of tolterodine extended release administered daily to 17 healthy male volunteers (13 EM, 4 PM). Table 3.

Summary of Mean (±SD) Pharmacokinetic Parameters of Tolterodine Extended Release and its Active Metabolite (5-Hydroxymethyl Tolterodine) in Healthy Volunteers C max = Maximum serum concentration; t max = Time of occurrence of C max ; C avg = Average serum concentration; t 1/2 = Terminal elimination half-life. Tolterodine 5-Hydroxymethyl Tolterodine t max Data presented as median (range). (h) C max (µg/L) C avg (µg/L) t 1/2 (h) t max (h) C max (µg/L) C avg (µg/L) t 1/2 (h) Single dose 4 mg Parameter dose-normalized from 8 to 4 mg for the single-dose data.

EM 4 (2–6) 1.3 (0.8) 0.8 (0.57) 8.4 (3.2) 4 (… [Excerpted — this section continues on DailyMed.]

12.2Pharmacodynamics Tolterodine has a pronounced effect on bladder function. Effects on urodynamic parameters before and 1 and 5 hours after a single 6.4 mg dose of tolterodine immediate release were determined in healthy volunteers. The main effects of tolterodine at 1 and 5 hours were an increase in residual urine, reflecting an incomplete emptying of the bladder, and a decrease in detrusor pressure.

These findings are consistent with an antimuscarinic action on the lower urinary tract. Cardiac Electrophysiology The effect of 2 mg BID and 4 mg BID of tolterodine immediate release tablets on the QT interval was evaluated in a 4-way crossover, double-blind, placebo- and active-controlled (moxifloxacin 400 mg QD) study in healthy male (N=25) and female (N=23) volunteers aged 18–55 years. Study subjects [approximately equal representation of CYP2D6 extensive metabolizers (EMs) and poor metabolizers (PMs)] completed sequential 4-day periods of dosing with moxifloxacin 400 mg QD, tolterodine 2 mg BID, tolterodine 4 mg BID, and placebo.

The 4 mg BID dose of tolterodine immediate release (two times the highest recommended dose) was chosen because this dose results in tolterodine exposure similar to that observed upon coadministration of tolterodine 2 mg BID with potent CYP3A4 inhibitors in patients who are CYP2D6 poor metabolizers [see Drug Interactions (7.2) ] . QT interval was measured over a 12-hour period following dosing, including the time of peak plasma concentration (T max ) of tolterodine and at steady state (Day 4 of dosing). Table 2 summarizes the mean change from baseline to steady state in corrected QT interval (QT c ) relative to placebo at the time of peak tolterodine (1 hour) and moxifloxacin (2 hour) concentrations.

Both Fridericia’s (QT c F) and a population-specific (QT c P) method were used to correct QT interval for heart rate. No single QT correction method is known to be more valid than others. QT interval was measured manually and by machine, and data from both are presented.

The mean increase of heart rate associated with a 4 mg/day dose of tolterodine in this study was 2.0 beats/minute and 6.3 beats/minute with 8 mg/day tolterodine. The change in heart rate with moxifloxacin was 0.5 beats/minute. Table 2.

Mean (CI) change in QTc from baseline to steady state (Day 4 of dosing) Drug/Dose N QT c F (msec) (manual) QT c F (msec) (machine) QT c P (msec) (manual) QT c P (msec) (machine) Tolterodine 2 mg BID At T max of 1 hr; 95% Confidence Interval. 48 5.01 (0.28, 9.74) 1.16 (-2.99, 5.30) 4.45 (-0.37, 9.26) 2.00 (-1.81, 5.81) Tolterodine 4 mg BID 48 11.84 (7.11, 16.58) 5.63 (1.48, 9.77) 10.31 (5.49, 15.12) 8.34 (4.53, 12.15) Moxifloxacin 400 mg QD At T max of 2 hr; 90% Confidence Interval. 45

19.26The effect on QT interval with 4 days of moxifloxacin dosing in this QT trial may be greater than typically observed in QT trials of other drugs. (15.49, 23.03) 8.90 (4.77, 13.03) 19.10 (15.32, 22.89) 9.29 (5.34, 13.24) The reason for the difference between machine and manual read of QT interval is unclear. The QT effect of tolterodine immediate release tablets appeared greater for 8 mg/day (two times the therapeutic dose) compared to 4 mg/day.

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. Tolterodine’s effect on QT interval was found to correlate with plasma concentration of tolterodine.

There appeared to be a greater QT c interval increase in CYP2D6 poor metabolizers than in CYP2D6 extensive metabolizers after tolterodine treatment in this study. This study was not designed to make direct statistical comparisons between drugs or dose levels. There has been no association of Torsade de Pointes in the international post-marketing experience with tolterodine tartrate extended-release capsules [see Warnings and Precautions (5.7) ] .

14 CLINICAL STUDIES Tolterodine tartrate extended-release capsules 2 mg were evaluated in 29 patients in a Phase 2 dose-effect study. Tolterodine tartrate extended-release capsules 4 mg were evaluated for the treatment of overactive bladder with symptoms of urge urinary incontinence and frequency in a randomized, placebo-controlled, multicenter, double-blind, Phase 3, 12-week study. A total of 507 patients received tolterodine tartrate extended-release capsules 4 mg once daily in the morning and 508 received placebo.

The majority of patients were Caucasian (95%) and female (81%), with a mean age of 61 years (range, 20 to 93 years). In the study, 642 patients (42%) were 65 to 93 years of age. The study included patients known to be responsive to tolterodine immediate release and other anticholinergic medications, however, 47% of patients never received prior pharmacotherapy for overactive bladder.

At study entry, 97% of patients had at least 5 urge incontinence episodes per week and 91% of patients had 8 or more micturitions per day. The primary efficacy assessment was change in mean number of incontinence episodes per week at week 12 from baseline. Secondary efficacy measures included change in mean number of micturitions per day and mean volume voided per micturition at week 12 from baseline.

Patients treated with tolterodine tartrate extended-release capsules experienced a statistically significant decrease in number of urinary incontinence per week from baseline to last assessment (week 12) compared with placebo as well as a decrease in the average daily urinary frequency and an increase in the average urine volume per void. Mean change from baseline in weekly incontinence episodes, urinary frequency, and volume voided between placebo and tolterodine tartrate extended-release capsules are summarized in Table 4.

Table 4. 95% Confidence Intervals (CI) for the Difference between Tolterodine Tartrate Extended-Release Capsules (4 mg daily) and Placebo for Mean Change at Week 12 from Baseline Intent-to-treat analysis. SD = Standard Deviation.

Tolterodine Tartrate Extended-Release Capsules (n=507) Placebo (n=508) 1 to 2 patients missing in placebo group for each efficacy parameter. Treatment Difference, vs. Placebo (95% Cl) Number of incontinence episodes/week Mean Baseline Mean Change from Baseline 22.1 –11.8 (SD 17.8) 23.3 –6.9 (SD 15.4) -4.8 The difference between tolterodine tartrate extended-release capsules and placebo was statistically significant.

(–6.9, –2.8) Number of micturitions/day Mean Baseline Mean Change from Baseline 10.9 –1.8 (SD 3.4) 11.3 –1.2 (SD 2.9) -0.6 (–1.0, –0.2) Volume voided per micturition (mL) Mean Baseline Mean Change from Baseline 141 34 (SD 51) 136 14 (SD 41) 20 (14, 26)

13 NONCLINICAL TOXICOLOGY

13.1Carcinogenesis, Mutagenesis, Impairment of Fertility Carcinogenicity studies with tolterodine were conducted in mice and rats. At the maximum tolerated dose in mice (30 mg/kg/day), female rats (20 mg/kg/day), and male rats (30 mg/kg/day), exposure margins were approximately 6-9 times, 7 times, and 11 times the clinical exposure to the pharmacologically active components of tolterodine tartrate extended-release capsules (based on AUC of tolterodine and its 5-HMT metabolite). At these exposure margins, no increase in tumors was found in either mice or rats.

No mutagenic or genotoxic effects of tolterodine were detected in a battery of in vitro tests, including bacterial mutation assays (Ames test) in 4 strains of Salmonella typhimurium and in 2 strains of Escherichia coli , a gene mutation assay in L5178Y mouse lymphoma cells, and chromosomal aberration tests in human lymphocytes. Tolterodine was also negative in vivo in the bone marrow micronucleus test in the mouse. In female mice treated for 2 weeks before mating and during gestation with 20 mg/kg/day (about 9-12 times the clinical exposure via AUC), neither effects on reproductive performance or fertility were seen.

In male mice, a dose of 30 mg/kg/day did not induce any adverse effects on fertility.