Clinical Pharmacology for VESIcare
Mechanism Of Action
Solifenacin is a competitive muscarinic receptor antagonist. Muscarinic receptors play an important role in several major cholinergically mediated functions, including contractions of urinary bladder smooth muscle.
Pharmacodynamics
Cardiac Electrophysiology
The effect of 10 mg and 30 mg solifenacin succinate (three times the maximum recommended dose) on the QT interval was evaluated at the time of peak plasma concentration of solifenacin in a multi-dose, randomized, double-blind, placebo and positive-controlled (moxifloxacin 400 mg) trial [see WARNINGS AND PRECAUTIONS]. After receiving placebo and moxifloxacin sequentially, subjects were randomized to one of two treatment groups. One group (n=51) completed 3 additional sequential periods of dosing with solifenacin succinate 10, 20, and 30 mg while the second group (n=25) in parallel completed a sequence of placebo and moxifloxacin. Study subjects were female volunteers aged 19 to 79 years. The 30 mg dose of solifenacin succinate (three times the highest recommended dose) was chosen for use in this study because this dose results in a solifenacin exposure that covers those observed upon coadministration of 10 mg VESIcare with strong CYP3A4 inhibitors (e.g., ketoconazole, 400 mg). Due to the sequential dose escalating nature of the study, baseline ECG measurements were separated from the final QT assessment (of the 30 mg dose level) by 33 days.
The median difference from baseline in heart rate associated with the 10 and 30 mg doses of solifenacin succinate compared to placebo was -2 and 0 beats/minute, respectively. Because a significant period effect on QTc was observed, the QTc effects were analyzed utilizing the parallel placebo control arm rather than the pre-specified intra-patient analysis. Representative results are shown in Table 2.
Table 2: QTc changes in msec (90% CI) from baseline at Tmax (relative to placebo)1
| Drug/Dose |
Fridericia method
(using mean difference) |
| Solifenacin succinate 10 mg |
2 (-3, 6) |
| Solifenacin succinate 30 mg |
8 (4, 13) |
| 1. Results displayed are those derived from the parallel design portion of the study and represent the comparison of Group 1 to time-matched placebo effects in Group 2. |
Moxifloxacin was included as a positive control in this study and, given the length of the study, its effect on the QT interval was evaluated in 3 different sessions. The placebo-subtracted mean changes (90% CI) in QTcF for moxifloxacin in the three sessions were 11 (7, 14), 12 (8, 17), and 16 (12, 21), respectively.
The QT interval prolonging effect of the highest solifenacin succinate dose (three times the maximum therapeutic dose) studied was not as large as that of the positive control moxifloxacin at its recommended dose. However, the confidence intervals overlapped, and this study was not designed to draw direct statistical conclusions between the drugs or the dose levels.
Pharmacokinetics
Absorption
After oral administration of VESIcare in healthy volunteers, peak plasma concentrations (Cmax) of solifenacin were reached within 3 to 8 hours after administration and, at steady-state, ranged from 32.3 to 62.9 ng/mL for the 5 and 10 mg VESIcare tablets, respectively. The absolute bioavailability of solifenacin is approximately 90%, with plasma concentrations of solifenacin proportional to the dose administered.
Effect of Food
VESIcare may be administered without regard to meals. A single 10 mg dose administration of VESIcare with food increased Cmax and AUC of solifenacin by 4% and 3%, respectively.
Distribution
Solifenacin is approximately 98% (in vivo) bound to human plasma proteins, principally to α1-acid glycoprotein. Solifenacin is highly distributed to non-CNS tissues, having a mean steady-state volume of distribution of 600 L.
Elimination
The elimination half-life (t1/2) of solifenacin following chronic dosing is approximately 45-68 hours.
Metabolism
Solifenacin is extensively metabolized in the liver. The primary pathway for elimination is by way of CYP3A4; however, alternate metabolic pathways exist. The primary metabolic routes of solifenacin are through N-oxidation of the quinuclidin ring and 4R-hydroxylation of the tetrahydroisoquinoline ring. One pharmacologically active metabolite (4R-hydroxy solifenacin), occurring at low concentrations and unlikely to contribute significantly to clinical activity, and three pharmacologically inactive metabolites (N-glucuronide and the N-oxide and 4R-hydroxy-N-oxide of solifenacin) have been found in human plasma after oral dosing.
Excretion
Following the administration of 10 mg of 14C-solifenacin succinate to healthy volunteers, 69% of the radioactivity was recovered in the urine and 23% in the feces over 26 days. Less than 15% (as mean value) of the dose was recovered in the urine as intact solifenacin. The major metabolites identified in urine were N-oxide of solifenacin, 4R-hydroxy solifenacin, and 4R-hydroxy-N-oxide of solifenacin and, in feces, 4R-hydroxy solifenacin.
Specific Populations
Geriatric Patients
Multiple dose studies of VESIcare in geriatric volunteers (65 to 80 years) showed that Cmax, AUC and t1/2 values of solifenacin were 20-25% higher compared to the younger adult volunteers (18 to 55 years). [see Use In Specific Populations].
Patients With Renal Impairment
In studies with solifenacin succinate 10 mg, there was a 2.1-fold increase in AUC and a 1.6-fold increase in t1/2 of solifenacin in patients with severe renal impairment compared to subjects with normal renal function [see Use In Specific Populations].
Patients With Hepatic Impairment
In studies with solifenacin succinate 10 mg, there was a 2-fold increase in the t1/2 and a 35% increase in AUC of solifenacin in patients with moderate hepatic impairment compared to subjects with normal hepatic function [see Use In Specific Populations]. VESIcare has not been studied in patients with severe hepatic impairment.
Drug Interaction Studies
Strong CYP3A4 Inhibitors
In a crossover study, following blockade of CYP3A4 by coadministration of the strong CYP3A4 inhibitor, ketoconazole 400 mg once daily for 21 days, the mean Cmax and AUC of solifenacin increased by 1.5 and 2.7-fold, respectively [see DOSAGE AND ADMINISTRATION and DRUG INTERACTIONS].
CYP3A4 Inducers
Because solifenacin is a substrate of CYP3A4, inducers of CYP3A4 may decrease the concentration of solifenacin.
Warfarin
In a crossover study, subjects received a single oral dose of warfarin 25 mg on the 10th day of dosing with either solifenacin succinate 10 mg or matching placebo once daily for 16 days. For R-warfarin, when it was coadministered with solifenacin succinate, the mean Cmax increased by 3% and AUC decreased by 2%. For S-warfarin, when it was coadministered with solifenacin succinate, the mean Cmax and AUC increased by 5% and 1%, respectively.
Oral Contraceptives
In a crossover study, subjects received 2 cycles of 21 days of oral contraceptives containing 30 ug ethinyl estradiol and 150 ug levonorgestrel. During the second cycle, subjects received additional solifenacin succinate 10 mg or matching placebo once daily for 10 days starting from the 12th day of receipt of oral contraceptives. For ethinyl estradiol, when it was administered with solifenacin succinate, the mean Cmax and AUC increased by 2% and 3%, respectively. For levonorgestrel, when it was administered with solifenacin succinate, the mean Cmax and AUC decreased by 1%.
Digoxin
In a crossover study, subjects received digoxin (loading dose of 0.25 mg on day 1, followed by 0.125 mg from days 2 to 8) for 8 days. Consecutively, they received solifenacin succinate 10 mg or matching placebo with digoxin 0.125 mg for an additional 10 days. When digoxin was coadministered with solifenacin succinate, the mean Cmax and AUC increased by 13% and 4%, respectively.
Drugs Metabolized By Cytochrome P450 Enzymes
In vitro studies demonstrated that, at therapeutic concentrations, solifenacin does not inhibit CYP1A1/2, 2C9, 2C19, 2D6, or 3A4 derived from human liver microsomes.
Animal Toxicology And/Or Pharmacology
Juvenile Animal Toxicology Data
Dose-related increased mortality without preceding clinical signs occurred in juvenile mice treated before weaning for a duration of 12 weeks, from day 10 after birth, with doses that achieved a pharmacological effect. Animals dosed from postnatal day 10 onwards had higher mortality compared to the mortality in adult mice. No increased frequency in mortality was observed in juvenile mice that were treated after weaning for a duration of 4 weeks, from day 21 after birth onwards. Plasma exposure at postnatal day 10 was higher than in adult mice; the systemic exposure at postnatal day 21 was comparable to the systemic exposure in adult mice.
Clinical Studies
VESIcare was evaluated in four twelve-week, double-blind, randomized, placebo-controlled, parallel group, multicenter clinical trials for the treatment of overactive bladder in adult patients having symptoms of urinary frequency, urgency, and/or urge or mixed incontinence (with a predominance of urge). Entry criteria required that patients have symptoms of overactive bladder for ≥ 3 months duration. These studies involved 3027 patients (1811 on VESIcare and 1216 on placebo), and approximately 90% of these patients completed the 12-week studies. Two of the four studies evaluated the 5 and 10 mg VESIcare doses (Studies 1 and 2) and the other two evaluated only the 10 mg dose (Studies 3 and 4). All patients completing the 12-week studies were eligible to enter an open-label, long-term extension study (Study 5) and 81% of patients enrolling completed the additional 40-week treatment period. The majority of patients were Caucasian (93%) and female (80%) with a mean age of 58 years.
The primary endpoint in all four trials was the mean change from baseline to 12 weeks in number of micturitions/24 hours. Secondary endpoints included mean change from baseline to 12 weeks in number of incontinence episodes/24 hours, and mean volume voided per micturition.
The efficacy of VESIcare was similar across patient age groups and gender. The mean reduction in the number of micturitions per 24 hours was significantly greater with VESIcare 5 mg (2.3; p < 0.001) and VESIcare 10 mg (2.7; p < 0.001) compared to placebo (1.4). The mean reduction in the number of incontinence episodes per 24 hours was significantly greater with VESIcare 5 mg (1.5; p < 0.001) and VESIcare 10 mg (1.8; p < 0.001) treatment groups compared to the placebo treatment group (1.1). The mean increase in the volume voided per micturition was significantly greater with VESIcare 5 mg (32.3 mL; p < 0.001) and VESIcare 10 mg (42.5 mL; p < 0.001) compared with placebo (8.5 mL).
The results for the primary and secondary endpoints in the four individual 12-week clinical studies of VESIcare are reported in Tables 3 through 6.
Table 3: Mean Changes from Baseline to Week 12 in Efficacy Endpoints in Study 1
| Parameter |
Placebo (N=253)
Mean (SE) |
VESIcare
5 mg
(N=266)
Mean (SE) |
VESIcare
10 mg
(N=264)
Mean (SE) |
| Urinary Frequency (Number of Micturitions/24 hours)1 |
| Baseline |
12.2 (0.26) |
12.1 (0.24) |
12.3 (0.24) |
| Reduction |
1.2 (0.21) |
2.2 (0.18) |
2.6 (0.20) |
| P value vs. placebo |
|
< 0.001 |
< 0.001 |
| Number of Incontinence Episodes/24 hours2 |
| Baseline |
2.7 (0.23) |
2.6 (0.22) |
2.6 (0.23) |
| Reduction |
0.8 (0.18) |
1.4 (0.15) |
1.5 (0.18) |
| P value vs. placebo |
2.7 (0.23) |
< 0.01 |
< 0.01 |
| Volume Voided per Micturition [mL]2 |
| Baseline |
143.8 (3.37) |
149.6 (3.35) |
147.2 (3.15) |
| Increase |
7.4 (2.28) |
32.9 (2.92) |
39.2 (3.11) |
| P value vs. placebo |
|
< 0.001 |
< 0.001 |
1. Primary endpoint
2. Secondary endpoint |
Table 4: Mean Changes from Baseline to Week 12 in Efficacy Endpoints in Study 2
| Parameter |
Placebo (N=281)
Mean (SE) |
VESIcare
5 mg
(N=286)
Mean (SE) |
VESIcare
10 mg
(N=290)
Mean (SE) |
| Urinary Frequency (Number of Micturitions/24 hours)1 |
| Baseline |
12.3 (0.23) |
12.1 (0.23) |
12.1 (0.21) |
| Reduction |
1.7 (0.19) |
2.4 (0.17) |
2.9 (0.18) |
| P value vs. placebo |
|
< 0.001 |
< 0.001 |
| Number of Incontinence Episodes/24 hours2 |
| Baseline |
3.2 (0.24) |
2.6 (0.18) |
2.8 (0.20) |
| Reduction |
1.3 (0.19) |
1.6 (0.16) |
1.6 (0.18) |
| P value vs. placebo |
|
< 0.01 |
0.016 |
| Volume Voided per Micturition [mL]2 |
| Baseline |
147.2 (3.18) |
148.5 (3.16) |
145.9 (3.42) |
| Increase |
11.3 (2.52) |
31.8 (2.94) |
36.6 (3.04) |
| P value vs. placebo |
|
< 0.001 |
< 0.001 |
1. Primary endpoint
2. Secondary endpoint |
Table 5: Mean Changes from Baseline to Week 12 in Efficacy Endpoints in Study 3
| Parameter |
Placebo (N=309)
Mean (SE) |
VESIcare
10 mg
(N=306)
Mean (SE) |
| Urinary Frequency (Number of Micturitions/24 hours)1 |
| Baseline |
11.5 (0.18) |
11.7 (0.18) |
| Reduction |
1.5 (0.15) |
3.0 (0.15) |
| P value vs. placebo |
|
< 0.001 |
| Number of Incontinence Episodes/24 hours2 |
| Baseline |
3.0 (0.20) |
3.1 (0.22) |
| Reduction |
1.1 (0.16) |
2.0 (0.19) |
| P value vs. placebo |
|
< 0.001 |
| Volume Voided per Micturition [mL]2 |
| Baseline |
190.3 (5.48) |
183.5 (4.97) |
| Increase |
2.7 (3.15) |
47.2 (3.79) |
| P value vs. placebo |
|
< 0.001 |
1. Primary endpoint
2. Secondary endpoint |
Table 6: Mean Changes from Baseline to Week 12 in Efficacy Endpoints in Study 4
| Parameter |
Placebo (N=295)
Mean (SE) |
VESIcare
10 mg
(N=298)
Mean (SE) |
| Urinary Frequency (Number of Micturitions/24 hours)1 |
| Baseline |
11.8 (0.18) |
11.5 (0.18) |
| Reduction |
1.3 (0.16) |
2.4 (0.15) |
| P value vs. placebo |
|
< 0.001 |
| Number of Incontinence Episodes/24 hours2 |
| Baseline |
2.9 (0.18) |
2.9 (0.17) |
| Reduction |
1.2 (0.15) |
2.0 (0.15) |
| P value vs. placebo |
|
< 0.001 |
| Volume Voided per Micturition [mL]2 |
| Baseline |
175.7 (4.44) |
174.1 (4.15) |
| Increase |
13.0 (3.45) |
46.4 (3.73) |
| P value vs. placebo |
|
< 0.001 |
1. Primary endpoint
2. Secondary endpoint |