Vesicare

Overdose

Overdosage with VESIcare can potentially result in severe anticholinergic effects and should be treated accordingly. The highest dose ingested in an accidental overdose of solifenacin succinate was 280 mg in a 5-hour period. This case was associated with mental status changes. Some cases reported a decrease in the level of consciousness.

Intolerable anticholinergic side effects (fixed and dilated pupils, blurred vision, failure of heel-to-toe exam, tremors and dry skin) occurred on day 3 in normal volunteers taking 50 mg daily (5 times the maximum recommended therapeutic dose) and resolved within 7 days following discontinuation of drug.

In the event of overdose with VESIcare, treat with gastric lavage and appropriate supportive measures. ECG monitoring is also recommended.

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Undesirable effects

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

VESIcare has been evaluated for safety in 1811 patients in randomized, placebo-controlled trials. Expected adverse reactions of antimuscarinic agents are dry mouth, constipation, blurred vision (accommodation abnormalities), urinary retention, and dry eyes. The incidence of dry mouth and constipation in patients treated with VESIcare was higher in the 10 mg compared to the 5 mg dose group.

In the four 12-week double-blind clinical trials, severe fecal impaction, colonic obstruction, and intestinal obstruction were reported in one patient each, all in the VESIcare 10 mg group. Angioneurotic edema has been reported in one patient taking VESIcare 5 mg. Compared to 12 weeks of treatment with VESIcare, the incidence and severity of adverse reactions were similar in patients who remained on drug for up to 12 months.

The most frequent adverse reaction leading to study discontinuation was dry mouth (1.5%). Table 1 lists the rates of identified adverse reactions, derived from all reported adverse events, in randomized, placebo-controlled trials at an incidence greater than placebo and in 1% or more of patients treated with VESIcare 5 or 10 mg once daily for up to 12 weeks.

Table 1: Percentages of Patients with Identified Adverse Reactions, Derived from All Adverse Events Exceeding Placebo Rate and Reported by 1% or More Patients for Combined Pivotal Studies

Because these spontaneously reported events are from the worldwide postmarketing experience, the frequency of events and the role of solifenacin in their causation cannot be reliably determined.

The following events have been reported in association with solifenacin use in worldwide postmarketing experience:

General:peripheral edema, hypersensitivity reactions, including angioedema with airway obstruction, rash, pruritus, urticaria, and anaphylactic reaction;

Central Nervous:headache, confusion, hallucinations, delirium and somnolence;

Cardiovascular:QT prolongation; Torsade de Pointes, atrial fibrillation, tachycardia, palpitations;

Hepatic:liver disorders mostly characterized by abnormal liver function tests, AST (aspartate aminotransferase), ALT (alanine aminotransferase), GGT (gamma-glutamyl transferase);

Renal:renal impairment;

Metabolism and nutrition disorders: decreased appetite, hyperkalemia;

Dermatologic:exfoliative dermatitis and erythema multiforme;

Eye disorders:glaucoma;

Gastrointestinal disorders:gastroesophageal reflux disease and ileus;

Respiratory, thoracic and mediastinal disorders: dysphonia;

Musculoskeletal and connective tissue disorders: muscular weakness;

Pharmacodynamic properties

The effect of 10 mg and 30 mg solifenacin succinate 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. Subjects were randomized to one of two treatment groups after receiving placebo and moxifloxacin sequentially. One group (n=51) went on to complete 3 additional sequential periods of dosing with solifenacin 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 co-administration of 10 mg VESIcare with potent CYP3A4 inhibitors (e.g. ketoconazole, 400 mg). Due to the sequential dose escalating nature of the study, baseline EKG 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)*

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 appeared greater for the 30 mg compared to the 10 mg dose of solifenacin. Although the effect of the highest solifenacin dose (three times the maximum therapeutic dose) studied did not appear as large as that of the positive control moxifloxacin at its therapeutic dose, the confidence intervals overlapped. This study was not designed to draw direct statistical conclusions between the drugs or the dose levels.

Pharmacokinetic properties

After oral administration of VESIcare to healthy volunteers, peak plasma levels (Cmax) of solifenacin are 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%, and plasma concentrations of solifenacin are proportional to the dose administered.

VESIcare may be administered without regard to meals. A single 10 mg dose administration of VESIcare with food increased Cmax and AUC by 4% and 3%, respectively.

Solifenacin is approximately 98% (in vivo) bound to human plasma proteins, principally to ∞1-acid glycoprotein. Solifenacin is highly distributed to non-CNS tissues, having a mean steady-state volume of distribution of 600L.

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 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.

Following the administration of 10 mg of 14C-solifenacin succinate to healthy volunteers, 69.2% of the radioactivity was recovered in the urine and 22.5% 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. The elimination half-life of solifenacin following chronic dosing is approximately 45-68 hours.

Date of revision of the text

Fertility, pregnancy and lactation

There are no adequate and well-controlled studies in pregnant women.

Reproduction studies have been performed in mice, rats and rabbits. After oral administration of 14C-solifenacin succinate to pregnant mice, drug-related material was shown to cross the placental barrier. No embryotoxicity or teratogenicity was observed in mice treated with 1.2 times (30 mg/kg/day) the expected exposure at the maximum recommended human dose [MRHD] of 10 mg. Administration of solifenacin succinate to pregnant mice at 3.6 times and greater (100 mg/kg/day and greater) the exposure at the MRHD, during the major period of organ development resulted in reduced fetal body weights. Administration of 7.9 times (250 mg/kg/day) the MRHD to pregnant mice resulted in an increased incidence of cleft palate. In utero and lactational exposures to maternal doses of solifenacin succinate of 3.6 times (100 mg/kg/day) the MRHD resulted in reduced peripartum and postnatal survival, reductions in body weight gain, and delayed physical development (eye opening and vaginal patency). An increase in the percentage of male offspring was also observed in litters from offspring exposed to maternal doses of 250 mg/kg/day. No embryotoxic effects were observed in rats at up to 50 mg/kg/day ( < 1 times the exposure at the MRHD) or in rabbits at up to 1.8 times (50 mg/kg/day) the exposure at the MRHD. Because animal reproduction studies are not always predictive of human response, VESIcare should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Interaction with other medicinal products and other forms of interaction

In a crossover study, following blockade of CYP3A4 by coadministration of the potent 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.

In a crossover study, subjects received a single oral dose of warfarin 25 mg on the 10th day of dosing with either solifenacin 10 mg or matching placebo once daily for 16 days. For R-warfarin when it was coadministered with solifenacin, the mean Cmax increased by 3% and AUC decreased by 2%. For S-warfarin when it was coadministered with solifenacin, the mean Cmax and AUC increased by 5% and 1%, respectively.

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 10 mg or matching placebo once daily for 10 days starting from 12th day of receipt of oral contraceptives. For ethinyl estradiol when it was administered with solifenacin, the mean Cmax and AUC increased by 2% and 3%, respectively. For levonorgestrel when it was administered with solifenacin, the mean Cmax and AUC decreased by 1%.

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 10 mg or matching placebo with digoxin 0.125 mg for additional 10 days. When digoxin was coadministered with solifenacin, the mean Cmax and AUC increased by 13% and 4%, respectively.