Tolterodine Tartrate (Page 3 of 6)

8.7 Hepatic Impairment

Liver impairment can significantly alter the disposition of tolterodine immediate release. In a study of tolterodine immediate release conducted in cirrhotic patients (Child-Pugh Class A and B), the elimination half-life of tolterodine immediate release was longer in cirrhotic patients (mean, 7.8 hours) than in healthy, young, and elderly volunteers (mean, 2 to 4 hours). The clearance of orally administered tolterodine immediate release was substantially lower in cirrhotic patients (1.0 ± 1.7 L/h/kg) than in the healthy volunteers (5.7 ± 3.8 L/h/kg). The recommended dose for patients with mild to moderate hepatic impairment (Child-Pugh Class A or B) is tolterodine tartrate extended-release capsules 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 WARNINGS AND PRECAUTIONS (5.4)].

10 OVERDOSAGE

Overdosage with tolterodine tartrate extended-release capsules can potentially result in severe central anticholinergic effects and should be treated accordingly.

ECG monitoring is recommended in the event of overdosage. In dogs, changes in the QT interval (slight prolongation of 10% to 20%) were observed at a suprapharmacologic dose of 4.5 mg/kg, which is about 68 times higher than the recommended human dose. In clinical trials of normal volunteers and patients, QT interval prolongation was observed with tolterodine immediate release at doses up to 8 mg (4 mg bid) and higher doses were not evaluated [see WARNINGS AND PRECAUTIONS (5.9) and CLINICAL PHARMACOLOGY (12.2)].

A 27-month-old child who ingested 5 to 7 tolterodine immediate release 2 mg tablets was treated with a suspension of activated charcoal and was hospitalized overnight with symptoms of dry mouth. The child fully recovered.

11 DESCRIPTION

Tolterodine tartrate extended-release capsule contain tolterodine tartrate, USP. The active moiety, tolterodine, is a muscarinic receptor antagonist. The chemical name of tolterodine tartrate, USP is (R)-N,N-diisopropyl-3-(2-hydroxy-5-methylphenyl)-3-phenylpropanamine L-hydrogen tartrate. The molecular formula of tolterodine tartrate, USP is C26 H37 NO7 ,. Its structure is:

structure

Tolterodine tartrate, USP is white to off-white powder with a molecular weight of 475.6. The pKa value is 9.87 and the solubility in water is 14.83 mg/mL. It is soluble in methanol, and sparingly soluble in water. The partition coefficient (Log D) between n-octanol and water is 1.83 at pH 7.3.

Tolterodine tartrate extended-release capsules 4 mg for oral administration contains 4 mg of tolterodine tartrate, USP. Inactive ingredients are microcrystalline cellulose, hypromellose, ethyl cellulose, medium chain triglycerides and oleic acids.

The capsule shell contains FD&C Blue 2, titanium dioxide and gelatin.

Tolterodine tartrate extended-release capsules 2 mg for oral administration contains 2 mg of tolterodine tartrate, USP. Inactive ingredients are microcrystalline cellulose, hypromellose, ethyl cellulose, medium chain triglycerides and oleic acids.

The capsule shell contains FD&C Blue 2, iron oxide yellow, titanium dioxide and gelatin.

Both the 2 mg and 4 mg capsule strengths are imprinted with a pharmaceutical grade printing ink that contains shellac, titanium dioxide, propylene glycol, and simethicone.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism 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 5HMT 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.

12.2 Pharmacodynamics

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 tartrate 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 to 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 IR (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 (Tmax ) 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 (QTc) relative to placebo at the time of peak tolterodine (1 hour) and moxifloxacin (2 hour) concentrations. Both Fridericia’s (QTcF) and a population-specific (QTcP) 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 QT c from baseline to steady state (Day 4 of dosing) at Tmax (relative to placebo)

* At Tmax of 1 hr; 95% Confidence Interval. At Tmax of 2 hr; 90% Confidence Interval. The 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.
Drug/Dose N QTc F (msec) (manual) QTc F (msec) (machine) QTc P (msec) (manual) QTc P (msec) (machine)
Tolterodine 2 mg BID* 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 † 45 19.26‡(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 QTc 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 tablets or tolterodine tartrate extended-release capsules [see WARNINGS AND PRECAUTIONS (5.7)].

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