oxybutynin

Absorption: Rapidly absorbed following oral administration, but undergoes extensive first-pass metabolism; extended-release tablets provide extended release. Transdermal absorption occurs by passive diffusion through intact skin and bypasses the first-pass effect.

Distribution: Highly bound (>99%) to plasma proteins. Widely distributed.

Metabolism/Excretion: Extensively metabolized by the liver via the CYP3A4 isoenzyme; one metabolite is pharmacologically active; metabolites are renally excreted with negligible (<0.1%) excretion of unchanged drug.

Half-Life: 7–8 hr (oral and patch); 30–64 hr (gel).

Time/Action Profile ⬆ ⬇

(urinary spasmolytic effect)

ROUTE	ONSET	PEAK	DURATION
PO	30–60 min	3–6 hr	6–10 hr (up to 24 hr with XL tablet)
TD-patch	within 24 hr	36 hr	3–4 days

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Uncontrolled angle-closure glaucoma;
Intestinal obstruction or atony;
Urinary retention.

Use Cautiously in:

Renal impairment;
Hepatic impairment;
Bladder outflow obstruction;
Ulcerative colitis;
Benign prostatic hyperplasia;
Cardiovascular disease;
Reflux esophagitis or gastrointestinal obstructive disorders;
Patients with dementia receiving acetylcholinesterase inhibitors;
Myasthenia gravis;
Parkinson's disease (may worsen symptoms);
Autonomic neuropathy (may worsen ↓ GI motility);
OB: Safety not established in pregnancy;
Lactation: Safety not established in breastfeeding;
Pedi: Safety not established in children 18 yr (patch and gel) or 5 yr (oral);
Geri: Poorly tolerated in older adults due to anticholinergic effects. Initiate treatment at lower doses.

Adv. Reactions/Side Effects ⬆ ⬇

CV: chest pain, edema, tachycardia

Derm: ↓sweating, transdermal only: application site reactions, hot flushes, pruritus

EENT: blurred vision, hoarseness

GI: constipation, dry mouth, nausea, abdominal pain, anorexia, diarrhea, dysphagia

GU: urinary retention, ↑thirst

Metab: hyperthermia

Neuro: dizziness, drowsiness, agitation, confusion, hallucinations, headache

Misc: HYPERSENSITIVITY REACTIONS (INCLUDING ANAPHYLAXIS AND ANGIOEDEMA)

Interactions ⬆ ⬇

Drug-drug:

↑anticholinergic effects with other agents having anticholinergic properties, including amantadine, antidepressants, phenothiazines, disopyramide, and haloperidol.
Additive CNS depression with other CNS depressants, including alcohol, antihistamines, antidepressants, opioids, and sedative/hypnotics.
Ketoconazole, itraconazole, erythromycin, and clarithromycin may ↑ effects.
May ↓ the GI promotility effects of metoclopramide.

Route/Dosage ⬆ ⬇

PO (Adults ): Immediate-release tablets: 5 mg 2–3 times daily (not to exceed 5 mg 4 times daily) (may start with 2.5 mg 2–3 times daily in elderly). Extended-release tablets: 5–10 mg once daily; may ↑, as needed (in 5-mg increments) up to maximum dose of 30 mg/day.
PO (Children >5 yr): Immediate-release tablets: 5 mg 2–3 times daily (not to exceed 15 mg/day). Extended-release tablets (children ≥6 yr): 5 mg once daily; may ↑, as needed, (in 5-mg increments) up to maximum dose of 20 mg/day.
PO (Children 1–5 yr): 0.2 mg/kg/dose 2–3 times daily.
Transdermal (Adults ): Patch: Apply one 3.9-mg system twice weekly (every 3–4 days); Gel: Apply contents of one sachet once daily.

Availability ⬆ ⬇

(Generic available)

Immediate-release tablets: 2.5 mg; 5 mg
Extended-release tablets: 5 mg; 10 mg; 15 mg
Syrup: 5 mg/5 mL
Transdermal gel: 10%
Transdermal patch: 3.9 mg/24 hr^OTC

Assessment ⬆ ⬇

Monitor voiding pattern and intake and output ratios, and assess abdomen for bladder distention prior to and periodically during therapy. Catheterization may be used to assess postvoid residual. Cystometry is usually performed to diagnose type of bladder dysfunction prior to prescription of oxybutynin.
Geri: Assess geriatric patients for anticholinergic effects (sedation and weakness).

Implementation ⬆ ⬇

Do not confuse oxybutynin with oxycodone, Oxycontin, or oxymorphone.
PO: Immediate-release tabs should be administered on an empty stomach; XL tablets may be given with or without food. DNC: Extended-release tablets should be swallowed whole; do not break, crush, or chew.
Transdermal patch: Apply patch on same two days each wk (Sunday/Wednesday, Monday/Thursday) to hip, abdomen, or buttock in an area that is clean, dry, and without irritation. Patch should be worn continuously.
Transdermal gel: Apply clear, colorless gel once daily to intact skin on abdomen (avoid area around navel), upper arms/shoulders, or thighs until dry. Rotate sites; do not use same site on consecutive days.

Patient/Family Teaching ⬆ ⬇

Instruct patient to take oxybutynin as directed. Take missed doses as soon as remembered unless almost time for next dose. Advise patient to read Information for the Patient prior to beginning therapy and with each Rx refill in case of new information.
May cause drowsiness or blurred vision. Advise patient to avoid driving and other activities requiring alertness until response to medication is known.
Advise patient to avoid concurrent use of alcohol and other CNS depressants while taking this medication.
Instruct patient that frequent rinsing of mouth, good oral hygiene, and sugarless gum or candy may decrease dry mouth. Notify health care professional if mouth dryness persists >2 wk.
Advise patient to stop taking oxybutynin and notify health care professional immediately if signs of angioedema and/or anaphylaxis (swelling of face, tongue, or throat; rash; dyspnea) occur.
Inform patient that oxybutynin decreases the body’s ability to perspire. Avoid strenuous activity in a warm environment because overheating may occur.
Advise patient to notify health care professional if urinary retention occurs or if constipation persists. Discuss methods of preventing constipation, such as increasing dietary bulk, increasing fluid intake, and increasing mobility.
Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
Rep: Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.
Discuss need for continued medical follow-up. Periodic cystometry may be used to evaluate effectiveness. Ophthalmic exams should be performed periodically to detect glaucoma, especially in patients over 40 yr of age.
Transdermal patch: Instruct patient on correct application and disposal of patch. Open pouch by tearing along arrows; apply immediately. Apply ½ patch to skin by removing ½ protective cover and applying firmly to skin. Apply 2nd half by bending in half and rolling patch onto skin while removing protective liner. Press patch firmly in place.
- Remove slowly; fold in half, sticky sides together, and discard. Wash site with mild soap and water or a small amount of baby oil.
- Advise patient referred for MRI to remove patch prior to test and give directions for replacing patch.
Transdermal gel: Instruct patient on correct application of oxybutynin gel. Do not apply to recently shaved skin, skin with rashes, or areas treated with lotions, oils, or powders; may be used with sunscreen. Wash area with mild soap and water and dry completely before applying. Tear packet open just before use and squeeze entire contents into hand or directly onto application site of abdomen, arms/shoulders, or thighs. Amount of gel will be size of a nickel on the skin. Gently rub into skin until dry. Wash hands immediately following application. Avoid application near open fire or when smoking; medication is flammable. Do not shower, bathe, swim, exercise, or immerse the application site in water within 1 hr after application. Cover application site with clothing if close skin-to-skin contact at application site is anticipated.

section name header

Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇