Solifenacin succinate is a competitive, specific muscarinic acetylcholine receptor antagonist used for the treatment of overactive bladder (OAB) syndrome with symptoms of urge urinary incontinence, urgency, and urinary frequency. It exhibits functional selectivity for the bladder over salivary glands, offering a favorable tolerability profile.
Adult: 5 mg once daily. May be increased to 10 mg once daily if the 5 mg dose is well tolerated but requires greater efficacy.
Note: Swallow the tablet whole with a glass of water, with or without food. Do not crush, chew, or split. Should be taken at approximately the same time each day.
Solifenacin is a competitive antagonist of muscarinic acetylcholine receptors (M1, M2, M3, M4, M5), with the highest functional selectivity for the M3 receptor subtype. In the bladder, M3 receptors are primarily responsible for detrusor muscle contraction. By blocking these receptors, solifenacin reduces involuntary detrusor contractions, increases bladder capacity, and decreases the frequency of micturition.
Pregnancy: Category C: Animal studies have shown adverse effects (embryolethality, retarded development). No adequate and well-controlled studies in pregnant women. Use only if potential benefit justifies potential risk to the fetus.
Driving: May cause blurred vision, dizziness, and somnolence. Patients should not drive or operate machinery until they know how the medicine affects them.
| Ketoconazole, Itraconazole, Voriconazole, Posaconazole | Potent CYP3A4 inhibitors increase solifenacin plasma levels. Risk of toxicity. | Major |
| Clarithromycin, Telithromycin, Erythromycin | Moderate CYP3A4 inhibitors may increase solifenacin exposure. | Moderate |
| Rifampicin, Carbamazepine, Phenytoin, St. John's Wort | Potent CYP3A4 inducers decrease solifenacin plasma levels, reducing efficacy. | Moderate |
| Other anticholinergics (e.g., oxybutynin, tolterodine, tricyclic antidepressants, first-gen antihistamines) | Additive anticholinergic side effects (dry mouth, constipation, blurred vision, cognitive effects). | Moderate |
| Drugs prolonging QT interval (e.g., Class Ia/III antiarrhythmics, macrolides, some antipsychotics) | Potential additive effect on QT prolongation, increasing arrhythmia risk. | Moderate |
| Metformin | Solifenacin may slightly decrease metformin absorption; monitor glycemic control. | Minor |
| Digoxin | Solifenacin may increase digoxin levels (P-gp inhibition); monitor digoxin levels. | Moderate |