Brands, Medical Use, Clinical Data
Drug Category
- Anticholinergic Agents
- Antispasmodics
- Genitourinary Smooth Muscle Relaxants
Dosage Forms
- Patch
- Syrup
- Tablet
- Tablet (extended-release)
Brands / Synonyms
Ditropan; Ditropan XL; Oxibutinina [Inn-Spanish]; Oxibutyninum; Oxybutinin; Oxybutynin; Oxybutynin Base; Oxybutynin Chloride; Oxybutynin Hydrochloride; Oxybutynine [Inn-French]; Oxybutyninum [Inn-Latin]; Oxytrol
Indications
For the treatment of overactive bladder.
Pharmacology
Oxybutynin is an antispasmodic, anticholinergic agent indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency. Oxybutynin relaxes bladder smooth muscle. Oxybutynin exhibits only one-fifth of the anticholinergic activity of atropine on the rabbit detrusor muscle, but four to ten times the antispasmodic activity. Antimuscarinic activity resides predominantly in the R-isomer.
Mechanism of Action
Oxybutynin exerts a direct antispasmodic effect on smooth muscle and inhibits the muscarinic action of acetylcholine on smooth muscle. No blocking effects occur at skeletal neuromuscular junctions or autonomic ganglia (antinicotinic effects).
Absorption
Rapidly absorbed from gastrointestinal tract.
Toxicity
LD50=1220 mg/kg (Orally in rats, Goldenthal)
Biotrnasformation / Drug Metabolism
Hepatic, primarily by CYP3A4
Contraindications
DITROPAN XL® is contraindicated in patients with urinary retention, gastric retention
and other severe decreased gastrointestinal motility conditions, uncontrolled narrow-angle glaucoma and in patients
who are at risk for these conditions.
DITROPAN XL is also contraindicated in patients who have demonstrated hypersensitivity to the drug
substance or other components of the product.
Drug Interactions
The concomitant use of oxybutynin with other anticholinergic drugs or with other agents which produce
dry mouth, constipation, somnolence (drowsiness), and/or other anticholinergic-like effects may increase the
frequency and/or severity of such effects.
Anticholinergic agents may potentially alter the absorption of some concomitantly administered drugs
due to anticholinergic effects on gastrointestinal motility. This may be of concern for drugs with a narrow
therapeutic index.
Mean oxybutynin chloride plasma concentrations were approximately 2 fold higher when DITROPAN XL was
administered with ketoconazole, a potent CYP3A4 inhibitor. Other inhibitors of the cytochrome P450 3A4 enzyme system,
such as antimycotic agents (e.g., itraconazole and miconazole) or macrolide antibiotics (e.g., erythromycin and
clarithromycin), may alter oxybutynin mean pharmacokinetic parameters (i.e., Cmax and AUC). The clinical
relevance of such potential interactions is not known. Caution should be used when such drugs are
co-administered.
Concurrent ingestion of antacid (20 mL of antacid containing aluminum hydroxide, magnesium hydroxide,
and simethicone) did not significantly affect the exposure of oxybutynin or desethyloxybutynin.
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