DITROPAN XL

Clinical safety rating: caution

Comprehensive clinical and safety monograph for DITROPAN XL (DITROPAN XL).

How it works

Oxybutynin is a competitive antagonist of muscarinic acetylcholine receptors (M1, M2, M3 subtypes), reducing detrusor muscle contraction and bladder smooth muscle spasm, thereby increasing bladder capacity and decreasing urge incontinence.

What the body does with it

Metabolism	Primarily hepatic via cytochrome P450 isoenzymes CYP3A4 and CYP3A5; undergoes extensive first-pass metabolism to active and inactive metabolites, including desethyloxybutynin (active).
Excretion	Approximately 50% of the administered dose is excreted in urine as unchanged drug and its active metabolite, N-desethyloxybutynin, with the remainder excreted in feces via biliary elimination.
Half-life	The terminal elimination half-life of oxybutynin is approximately 12-13 hours for the immediate-release formulation, but for DITROPAN XL, due to its extended-release profile, the effective half-life is extended, allowing once-daily dosing. Clinical context: steady-state is achieved within 3 days of dosing.
Protein binding	Approximately 90-95% bound to plasma proteins, primarily to albumin and alpha-1-acid glycoprotein.
Volume of Distribution	The apparent volume of distribution (Vd) is approximately 1.2 L/kg, indicating extensive distribution into extravascular tissues.
Bioavailability	Oral (extended-release): Bioavailability is approximately 10-20% due to extensive first-pass metabolism via cytochrome P450 3A4 isoenzymes.
Onset of Action	Oral (extended-release): Onset of anticholinergic effects (e.g., reduction in urinary frequency) is typically observed within 1-2 hours following administration.
Duration of Action	Oral (extended-release): Duration of action is approximately 24 hours, supporting once-daily dosing. Clinical notes: controlled release maintains therapeutic plasma concentrations over the dosing interval.

Classification & Brands

Dosing & administration

Oral: 5 to 10 mg once daily; maximum 30 mg once daily.

Dosage form	TABLET, EXTENDED RELEASE
Renal impairment	CrCl <30 mL/min: Use not recommended; no specific dose adjustment available.
Liver impairment	Child-Pugh Class A: No adjustment; Child-Pugh Class B: Use with caution, consider dose reduction; Child-Pugh Class C: Use not recommended.
Pediatric use	Children ≥6 years: Oral, 5 mg once daily, may increase to 10 mg once daily based on response and tolerability.
Geriatric use	Start with 5 mg once daily; titrate cautiously due to increased anticholinergic sensitivity and risk of cognitive impairment.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for DITROPAN XL (DITROPAN XL).

Breastfeeding	Oxybutynin is excreted into breast milk in small amounts; M/P ratio not reported. No adverse effects in infants are documented, but due to anticholinergic properties, monitor for infant drowsiness, constipation, or decreased feeding. Use only if clearly needed.
Teratogenic Risk	FDA Pregnancy Category B. Oxybutynin did not demonstrate teratogenicity in animal studies at doses up to 20 times the human dose. However, no adequate human studies exist. Avoid in first trimester unless benefit outweighs risk. In second and third trimesters, use caution; oxybutynin may cross the placenta and cause anticholinergic effects in the fetus (e.g., tachycardia, meconium ileus).

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

Absolute: Hypersensitivity to oxybutynin or any component, untreated narrow-angle glaucoma, urinary retention, gastric retention. Relative: Severe hepatic impairment, myasthenia gravis, severe ulcerative colitis, toxic megacolon.

Clinical Precautions

Precautions

May worsen myasthenia gravis; use caution in patients with gastrointestinal obstructive disorders, decreased gastrointestinal motility, ulcerative colitis, hiatal hernia with reflux esophagitis, and hepatic or renal impairment. May cause heat prostration in hot environments. Avoid use in patients with bladder outflow obstruction or narrow-angle glaucoma.

Clinical Tips & Counseling

Drug interactions

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DITROPAN XL

Clinical safety rating: caution

Comprehensive clinical and safety monograph for DITROPAN XL (DITROPAN XL).

How it works

What the body does with it

Metabolism	Primarily hepatic via cytochrome P450 isoenzymes CYP3A4 and CYP3A5; undergoes extensive first-pass metabolism to active and inactive metabolites, including desethyloxybutynin (active).
Excretion	Approximately 50% of the administered dose is excreted in urine as unchanged drug and its active metabolite, N-desethyloxybutynin, with the remainder excreted in feces via biliary elimination.
Half-life	The terminal elimination half-life of oxybutynin is approximately 12-13 hours for the immediate-release formulation, but for DITROPAN XL, due to its extended-release profile, the effective half-life is extended, allowing once-daily dosing. Clinical context: steady-state is achieved within 3 days of dosing.
Protein binding	Approximately 90-95% bound to plasma proteins, primarily to albumin and alpha-1-acid glycoprotein.
Volume of Distribution	The apparent volume of distribution (Vd) is approximately 1.2 L/kg, indicating extensive distribution into extravascular tissues.
Bioavailability	Oral (extended-release): Bioavailability is approximately 10-20% due to extensive first-pass metabolism via cytochrome P450 3A4 isoenzymes.
Onset of Action	Oral (extended-release): Onset of anticholinergic effects (e.g., reduction in urinary frequency) is typically observed within 1-2 hours following administration.
Duration of Action	Oral (extended-release): Duration of action is approximately 24 hours, supporting once-daily dosing. Clinical notes: controlled release maintains therapeutic plasma concentrations over the dosing interval.

Classification & Brands

Dosing & administration

Oral: 5 to 10 mg once daily; maximum 30 mg once daily.

Dosage form	TABLET, EXTENDED RELEASE
Renal impairment	CrCl <30 mL/min: Use not recommended; no specific dose adjustment available.
Liver impairment	Child-Pugh Class A: No adjustment; Child-Pugh Class B: Use with caution, consider dose reduction; Child-Pugh Class C: Use not recommended.
Pediatric use	Children ≥6 years: Oral, 5 mg once daily, may increase to 10 mg once daily based on response and tolerability.
Geriatric use	Start with 5 mg once daily; titrate cautiously due to increased anticholinergic sensitivity and risk of cognitive impairment.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for DITROPAN XL (DITROPAN XL).

Breastfeeding	Oxybutynin is excreted into breast milk in small amounts; M/P ratio not reported. No adverse effects in infants are documented, but due to anticholinergic properties, monitor for infant drowsiness, constipation, or decreased feeding. Use only if clearly needed.
Teratogenic Risk	FDA Pregnancy Category B. Oxybutynin did not demonstrate teratogenicity in animal studies at doses up to 20 times the human dose. However, no adequate human studies exist. Avoid in first trimester unless benefit outweighs risk. In second and third trimesters, use caution; oxybutynin may cross the placenta and cause anticholinergic effects in the fetus (e.g., tachycardia, meconium ileus).

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

Clinical Precautions

Precautions

Clinical Tips & Counseling

Drug interactions

Loading safety data…