OXYBUTYNIN CHLORIDE

OXYBUTYNIN CHLORIDE (ox-i-byoo'ti-nin) Ditropan, Ditropan XL, Oxytrol Classifications: anticholinergic; antimuscarinic; antispasmodic; Therapeutic: antispasmodic; anticholinergic Prototype: Atropine Pregnancy Category: B

Availability

5 mg tablets; 5 mg, 10 mg sustained release tablets; 5 mg/5 mL syrup; 3.9 mg/d transdermal patch

Action

Synthetic tertiary amine that exerts direct antispasmodic action and inhibits muscarinic effects of acetylcholine on smooth muscle of the urinary muscle.

Therapeutic Effect

Prominent antispasmodic activity of the urinary muscle.

Uses

To relieve symptoms associated with voiding in patients with uninhibited neurogenic bladder and reflex neurogenic bladder. Also has been used to relieve pain of bladder spasm following transurethral surgical procedures.

Contraindications

Hypersensitivity of oxybutynin; narrow angle glaucoma, myasthenia gravis, partial or complete GI obstruction, gastric retention, paralytic ileus, intestinal atony (especially older adult or debilitated patients), megacolon, severe colitis, GU obstruction, urinary retention, unstable cardiovascular status; extended release form with renal impairment; lactation, infants.

Cautious Use

Older adults; autonomic neuropathy, hiatus hernia with reflex esophagitis; hepatic or renal dysfunction; urinary infection; hyperthyroidism; CHF, coronary artery disease, hypertension; prostatic hypertrophy; pregnancy (category B).

Route & Dosage

Neurogenic Bladder Adult: PO 5 mg b.i.d. or t.i.d. (max: 20 mg/d) or 5 mg sustained release q.d., may increase up to 30 mg/d Topical Apply 1 patch twice weekly Geriatric: PO 2.5–5 mg b.i.d. (max: 15 mg/d) or 5 mg sustained release q.d., may increase up to 30 mg/d Topical Apply 1 patch twice weekly Child: PO 1–5 y, 0.2 mg/kg b.i.d.–q.i.d.; >5 y, 5 mg b.i.d. (max: 15 mg/d)

Administration

Oral

• Ensure that sustained release form is not chewed or crushed. It must be swallowed whole.

Topical

• Ensure that old patch is removed prior to application of new patch.

Adverse Effects (≥1%)

Body as a Whole: Severe allergic reactions including urticaria, skin rashes, suppression of lactation, decreased sweating, fever. CNS: Drowsiness, dizziness, weakness, insomnia, restlessness, psychotic behavior (overdosage). CV: Palpitations, tachycardia, flushing. Special Senses: Mydriasis, blurred vision, cycloplegia, increased ocular tension. GI: Dry mouth, nausea, vomiting, constipation, bloated feeling. Skin: Pruritus at application site, rash, application site vesicles, erythema. Urogenital: Urinary hesitancy or retention, impotence.

Pharmacokinetics

Absorption: Diffuses across intact skin. Onset: 0.5–1 h. Peak: 3–6 h. Duration: 6–10 h. PO: 96 h transdermal. Metabolism: In liver. Elimination: Primarily in urine. Half-Life: 2–5 h

Nursing Implications

Assessment & Drug Effects

• Periodic interruptions of therapy are recommended to determine patient's need for continued treatment. Tolerance has occurred in some patients.
• Keep physician informed of expected responses to drug therapy (e.g., effect on urinary frequency, urgency, urge incontinence, nocturia, completeness of bladder emptying).
• Monitor patients with colostomy or ileostomy closely; abdominal distension and the onset of diarrhea in these patients may be early signs of intestinal obstruction or of toxic megacolon.

Patient & Family Education

• Do not drive or engage in potentially hazardous activities until response to drug is known.
• Exercise caution in hot environments. By suppressing sweating, oxybutynin can cause fever and heat stroke.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug