Solifenacin

Oral
Overactive bladder

Oral
Neurogenic detrusor overactivity

Overactive bladder:
Patient taking strong CYP3A4 inhibitors (e.g. ketoconazole, ritonavir): Max: 5 mg once daily.

Neurogenic detrusor overactivity:
Patient taking strong CYP3A4 inhibitors (e.g. ketoconazole, ritonavir): Do not use more than the recommended initial doses.

Overactive bladder:

CrCl (mL/min)	Dosage
≤30	Severe: Max: 5 mg once daily.

Neurogenic detrusor overactivity:

CrCl (mL/min)	Dosage
≤30	Severe: Do not use more than the recommended initial doses.

Overactive bladder:
Moderate (Child-Pugh class B): Max: 5 mg once daily. Severe (Child-Pugh class C): Contraindicated.

Neurogenic detrusor overactivity:
Moderate (Child-Pugh class B): Do not use more than the recommended initial doses. Severe (Child-Pugh class C): Contraindicated.

May be taken with or without food. Swallow whole, do not chew/crush.

Myasthenia gravis, uncontrolled narrow-angle glaucoma, severe gastrointestinal condition (e.g. toxic megacolon, gastric retention); urinary retention (when used for overactive bladder). Patient undergoing haemodialysis. Severe hepatic impairment (Child-Pugh class C). Concomitant use with strong CYP3A4 inhibitors in patients with severe renal or moderate hepatic impairment.

Patient with controlled narrow-angle glaucoma; Alzheimer's disease; known history of or predisposition to QT prolongation (e.g. hypokalaemia, concomitant use of drugs known to prolong QT interval); significant pre-existing cardiac disease (e.g. CHF, arrhythmia, myocardial ischaemia), risk of decreased gastrointestinal motility, gastrointestinal obstructive disorders; autonomic neuropathy, GERD, hiatus hernia. Not recommended for use in patients with significant bladder outlet obstruction (e.g. BPH) who are being treated for overactive bladder. Patient subjected to hot weather and/or exercise. Patient taking strong CYP3A4 inhibitors. Severe renal (CrCl ≤30 mL/min) and moderate hepatic (Child-Pugh class B) impairment. Children. Pregnancy and lactation.

Significant: QT prolongation and torsades de pointes (particularly in patients with known risk factors), CNS effects (e.g. headache, confusion, hallucinations, somnolence), heat prostration (in presence of high environmental temperature). Rarely, faecal impaction, colonic obstruction, intestinal obstruction; urinary retention.
Eye disorders: Blurred vision, dry eyes.
Gastrointestinal disorders: Dry mouth, nausea, abdominal pain, dyspepsia, constipation, dysgeusia, GERD, dry throat.
General disorders and administration site conditions: Fatigue, peripheral oedema.
Renal and urinary disorders: Cystitis, UTI, difficulty in micturition.
Respiratory, thoracic and mediastinal disorders: Nasal dryness.
Skin and subcutaneous tissue disorders: Dry skin.
Potentially Fatal: Angioedema associated with swelling of the upper airway. Rarely, anaphylactic reactions.

PO: C

This drug may cause blurred vision, and uncommonly, drowsiness and tiredness, if affected, do not drive or operate machinery.

Evaluate other causes of frequent urination (e.g. heart failure, renal disease) prior to treatment. Monitor creatinine clearance, hepatic function, and urination pattern. Assess for signs and symptoms of anticholinergic effects (e.g. headache, confusion, hallucination, somnolence, fixed and dilated pupils, blurred vision, tremors, dry skin).

Symptoms: Severe anticholinergic effects (e.g. blurred vision, fixed and dilated pupils, tremors, dry skin). Management: Symptomatic and supportive treatment. Administer activated charcoal. Perform gastric lavage within 1 hour of ingestion but vomiting must not be induced. Give physostigmine or carbachol to treat hallucinations or pronounced excitation; benzodiazepines for convulsions; β-blockers for tachycardia. Administer pilocarpine eye drops and/or place the patient in a dark room in case of mydriasis. Employ artificial respiration during respiratory insufficiency and catheterisation for urinary retention. Monitor ECG as necessary.

Increased plasma concentration with strong CYP3A4 inhibitors (e.g. ketoconazole, ritonavir, nelfinavir, itraconazole). May enhance the therapeutic effects and adverse reactions when used concomitantly with other agents with anticholinergic activity; an interval of approx 1 week between using these drugs is recommended. May reduce efficacy with cholinergic receptor agonists. Efficacy of drugs that stimulate gastrointestinal motility (e.g. metoclopramide, cisapride) may be reduced by solifenacin.

May increase serum levels with grapefruit juice.

Description: Solifenacin is a selective, competitive inhibitor of the muscarinic M₃ subtype receptor, which causes a decrease in urinary bladder contraction and detrusor muscle pressure, and an increase in residual urine volume.
Pharmacokinetics:
Absorption: Absorbed from the gastrointestinal tract. Bioavailability: Approx 90%. Time to peak plasma concentration: 3-8 hours (tab); 4-12 hours (oral susp).
Distribution: Plasma protein binding: Approx 98%, mainly to α₁-acid glycoprotein.
Metabolism: Extensively metabolised in the liver, mainly by the CYP3A4 isoenzyme, but alternative metabolic pathways may also contribute; metabolism via N-oxidation and 4R-hydroxylation forms 1 active metabolite (4R-hydroxy solifenacin) and 3 inactive metabolites (N-glucuronide, N-oxide, and 4R-hydroxy-N-oxide solifenacin).
Excretion: Via urine (approx 70%; approx 11% as unchanged drug, 8% as the active metabolite, 9% as the 4R-hydroxy-N-oxide metabolite, 18% as the N-oxide metabolite); faeces (23%). Terminal elimination half-life: 45-68 hours (adults); approx 26 hours (children).

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 154059, Solifenacin. https://pubchem.ncbi.nlm.nih.gov/compound/Solifenacin. Accessed Nov. 25, 2021.

Store between 15-30°C. Protect from light (oral susp).

Other Drugs Acting on the Genito-Urinary System

G04BD08 - solifenacin ; Belongs to the class of urinary antispasmodics.

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