Home Drug Guide Oxybutynin Chloride

Drug Guide

Generic Name

Oxybutynin Chloride

Brand Names Ditropan, Ditropan XL, Gelnique

Classification

Therapeutic: Urinary antispasmodic, anticholinergic agent

Pharmacological: Antimuscarinic agent

FDA Approved Indications

Overactive bladder with symptoms of urinary frequency, urgency, and incontinence

Mechanism of Action

Oxybutynin is an anticholinergic that inhibits the muscarinic receptors in the bladder detrusor muscle, reducing involuntary bladder contractions and increasing bladder capacity.

Dosage and Administration

Adult: Initially 5 mg 2-3 times daily; may increase to 5-10 mg 2-3 times daily based on response and tolerability. For extended-release, 5 mg once daily, titratable to 10-15 mg daily.

Pediatric: Not generally recommended for children.

Geriatric: Start at lower end of dosing range due to increased sensitivity and risk of anticholinergic side effects.

Renal Impairment: Use with caution; consider dose adjustment as needed.

Hepatic Impairment: Use with caution; no specific dosage adjustments established.

Pharmacokinetics

Absorption: Well absorbed after oral administration, bioavailability approximately 60% due to first-pass metabolism.

Distribution: Widely distributed; crosses the blood-brain barrier.

Metabolism: Primarily hepatic via CYP3A4 and CYP2D6 enzymes.

Excretion: Excreted mainly in urine as metabolites, some unchanged drug.

Half Life: 3-7 hours for immediate-release; 7-8 hours for extended-release formulations.

Contraindications

Urinary retention
Gastric retention/paralytic ileus
Uncontrolled narrow-angle glaucoma
Hypersensitivity to oxybutynin

Precautions

Use with caution in patients with myasthenia gravis, ulcerative colitis, or urinary tract infections. Caution in elderly due to side effects.

Adverse Reactions - Common

Dry mouth (Common)
Constipation (Common)
Drowsiness/dizziness (Common)
Blurred vision (Common)

Adverse Reactions - Serious

Angioedema (Rare)
Urinary retention (Rare)
Severe allergic reactions (Rare)

Drug-Drug Interactions

Other anticholinergic drugs; CYP3A4 or CYP2D6 inhibitors or inducers may alter oxybutynin levels.

Drug-Food Interactions

Alcohol may enhance sedative effects.

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor for urinary retention, dry mouth, confusion, and visual disturbances.

Diagnoses:

Risk for urinary retention
Risk for falls related to dizziness or blurred vision

Implementation: Administer with food to decrease gastrointestinal upset; instruct patients to rise slowly to prevent dizziness.

Evaluation: Assess symptom relief and monitor for adverse effects.

Patient/Family Teaching

Advise patients to avoid activities requiring alertness until drug effects are known.
Instruct on proper administration times.
Warn about potential side effects, especially dry mouth and dizziness.
Encourage adequate fluid intake and good oral hygiene.

Special Considerations

Black Box Warnings:

None specific for this medication.

Genetic Factors: Genetic polymorphisms in CYP enzymes may affect metabolism.

Lab Test Interference: May cause false positives for urinary catecholamines and metanephrines.

Overdose Management

Signs/Symptoms: Severe anticholinergic toxicity including hallucinations, delirium, convulsions, hyperthermia, dry skin/mucous membranes, mydriasis, tachycardia, urinary retention.

Treatment: Supportive care, activated charcoal if ingestion is recent, physostigmine may be used cautiously under medical supervision for severe toxicity.

Storage and Handling

Storage: Store at room temperature, 20°C to 25°C (68°F to 77°F). Keep away from moisture and heat.

Stability: Stable for at least 2 years if properly stored.