SOLIFENACIN SUCCINATE
Clinical safety rating: safe
Animal studies have demonstrated safety
Solifenacin is a competitive muscarinic receptor antagonist. It binds selectively to M3 muscarinic receptors, inhibiting acetylcholine action on smooth muscle of the urinary bladder, reducing detrusor overactivity and increasing bladder capacity.
| Metabolism | Primarily metabolized by CYP3A4 to active metabolites including 4R-hydroxy solifenacin and N-glucuronide conjugates. Minor contribution from CYP2C9 and CYP2C19. |
| Excretion | Primarily renal: ~69% as metabolites (including active metabolite 4R-hydroxy solifenacin) and ~7% as unchanged drug. Fecal excretion accounts for ~23% (mainly as metabolites). |
| Half-life | Terminal elimination half-life is approximately 45-68 hours (mean ~55 hours) in healthy adults, allowing once-daily dosing. |
| Protein binding | Approximately 98% bound to plasma proteins (primarily alpha-1-acid glycoprotein). |
| Volume of Distribution | Vd/F is approximately 600 L (~8.6 L/kg for a 70 kg person), indicating extensive tissue distribution. |
| Bioavailability | Absolute oral bioavailability is approximately 88% (range 80-95%), not significantly affected by food. |
| Onset of Action | Oral: Onset of anticholinergic effect (e.g., reduction in urinary frequency) occurs within 3-8 hours after first dose, with peak effect at steady state (by day 10-14). |
| Duration of Action | Duration of antimuscarinic effect supports once-daily dosing; effect persists for up to 24 hours. Clinical benefit (e.g., decreased incontinence episodes) continues with regular dosing. |
| Molecular Weight | 480.56 |
5 mg orally once daily, may increase to 10 mg once daily if tolerated.
| Dosage form | TABLET |
| Renal impairment | eGFR 30-89 mL/min/1.73 m²: No adjustment. eGFR <30 mL/min/1.73 m²: Not recommended (insufficient data). |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: 5 mg once daily; no data for Child-Pugh C. |
| Pediatric use | Safety and efficacy not established in pediatric patients. |
| Geriatric use | Start at 5 mg once daily; monitor for anticholinergic effects; no specific dose adjustment required based on age alone. |
| 1st trimester | Limited data; animal studies show no teratogenic effects at clinically relevant doses. Use only if clearly needed. |
| 2nd trimester | Limited data; no known malformations reported. Consider risk-benefit. |
| 3rd trimester | Potential for oligohydramnios and neonatal anticholinergic effects (e.g., constipation, urinary retention) due to inhibition of muscarinic receptors. Avoid use near term. |
Clinical note
Strong CYP3A4 inhibitors may increase levels Can cause blurred vision and urinary retention.
| Placental transfer | Crosses placenta; concentration in cord blood is low, likely due to high protein binding and molecular weight. |
| Breastfeeding | Excretion into human milk occurs in low amounts; relative infant dose estimated <10%. No adverse effects reported in breastfed infants. Monitor for anticholinergic side effects (drowsiness, constipation). |
■ FDA Black Box Warning
None
| Common Effects | Dry mouth |
| Serious Effects |
Urinary retentionGastric retentionUncontrolled narrow-angle glaucomaHypersensitivity to solifenacin or any component
| Precautions | Angioedema of the face, lips, tongue, and/or larynx has been reported, requiring immediate treatment discontinuation., Urinary retention: Use with caution in patients with clinically significant bladder outflow obstruction., Gastric retention: Use with caution in patients with decreased gastrointestinal motility., Prolonged QT interval: Use with caution in patients with known QT prolongation or those taking drugs known to prolong QT interval., Central nervous system effects: Somnolence, dizziness, and blurred vision have been reported; advise caution when driving or operating machinery., Hepatic impairment: Not recommended in severe hepatic impairment (Child-Pugh Class C). |
| Food/Dietary |
Loading safety data…
| Lactation Rating | L2 (Probably Compatible) |
| Teratogenic Risk | FDA Pregnancy Category C. No adequate studies in pregnant women. In animal studies, solifenacin caused fetal malformations (cleft palate, skeletal abnormalities) at doses equivalent to human exposures. Risk cannot be ruled out. First trimester: potential teratogenic risk based on animal data; use only if benefit outweighs risk. Second/third trimester: limited data; may cause anticholinergic effects in fetus (e.g., tachycardia, meconium ileus). Avoid use during pregnancy unless essential. |
| Fetal Monitoring | Monitor for maternal anticholinergic side effects (constipation, dry mouth, blurred vision, urinary retention). Fetal monitoring: assess growth and amniotic fluid volume via ultrasound if prolonged use in second/third trimester. Monitor neonate for anticholinergic effects (e.g., feeding difficulties, tachycardia) after delivery if used near term. |
| Fertility Effects | Animal studies show no impairment of fertility at clinically relevant exposures. In humans, no specific data on fertility effects. Anticholinergic properties may theoretically affect reproductive function (e.g., vaginal dryness), but no conclusive evidence of significant impact on fertility. |
| Grapefruit and grapefruit juice may increase solifenacin exposure; avoid concurrent use. High-fat meals may delay absorption but do not affect overall exposure; take consistently with or without food. |
| Clinical Pearls | Solifenacin is a bladder-selective antimuscarinic; avoid in patients with narrow-angle glaucoma, significant bladder outflow obstruction, or severe hepatic impairment (Child-Pugh C). QT prolongation risk; monitor ECG in patients with risk factors. Adjust dose for renal impairment (CrCl <30 mL/min: maximum 5 mg/day). For hepatic impairment (Child-Pugh B): maximum 5 mg/day. Onset within 1 week; full effect may take 4 weeks. Consider residual urine volume monitoring if urinary retention suspected. |
| Patient Advice | Take exactly as prescribed; swallow tablet whole with water, can take with or without food. · Do not crush or chew the tablet. · May cause dry mouth, constipation, blurred vision; report blurred vision, difficulty urinating, or severe abdominal pain. · Limit alcohol and caffeine intake as they may worsen bladder symptoms. · Avoid driving or operating machinery if you experience blurred vision or dizziness. · Avoid excessive heat exposure because of decreased sweating risk. · Store at room temperature away from moisture and heat. |