DARIFENACIN HYDROBROMIDE
| Darifenacin Hydrobromide (dar-i-fen'a-sin) Enablex Classifications: anticholinergic; muscarinic receptor antagonist; bladder antispasmodic; Therapeutic: bladder antispasmodic; muscarinic receptor antagonist Prototype: Ipratropium Pregnancy Category: C |
Availability
7.5 mg and 15 mg extended release tablets
Action
Darifenacin is a selective M3 muscarinic receptor antagonist. Muscarinic M3 receptors play an important role in contraction of the urinary bladder smooth muscle and stimulation of salivary secretion.
Therapeutic Effect
Control of urinary incontinence due to urgency and frequency.
Uses
Treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency.
Contraindications
Hypersensitivity to the drug; severe hepatic impairment (Child-Pugh C class); urinary retention; gastric obstruction; pyloric stenosis, ileus; urinary retention; uncontrolled narrow-angle glaucoma; pregnancy (category C).
Cautious Use
Risk of urinary retention, clinically significant bladder outflow obstruction, renal disease; decreased GI motility, GERD, severe constipation, ulcerative colitis; myasthenia gravis; controlled narrow-angle glaucoma; lactation.
Route & Dosage
| Overactive Bladder Adult: PO 7.5–15 mg qd Moderate Hepatic Impairment (Child-Pugh B Class) Max dose: ≤ 7.5 mg qd |
Administration
Oral- Ensure that the drug is not chewed or crushed. It must be swallowed whole.
- Note: Dosage should not exceed 7.5 mg daily with moderate hepatic impairment (i.e., Child-Pugh B class) or concurrent therapy with potent inhibitors of CYP3A4 (e.g., itraconazole, clarithromycin, nefazodone, nelfinavir, ritonavir).
- Store 15°–30° C (59°–86° F). Protect from light.
Adverse Effects (≥1%)
Body as a Whole: Flu-like symptoms, urinary tract infection. CNS: Headache, asthenia, dizziness. GI: Constipation, dry mouth, dyspepsia, nausea, abdominal pain, diarrhea.Interactions
Drug: Potent inhibitors of CYP3A4 (e.g., clarithromycin, erythromycin, itraconazole, ketoconazole, nefazodone, nelfinavir, and ritonavir) increase darifenacin levels. Darifenacin will cause additive anticholinergic effects with other anticholinergic drugs. Darifenacin can increase digoxin concentrations. Food: Grapefruit juice may increase darifenacin levels.Pharmacokinetics
Absorption: 15–19% bioavailability. Peak: 7h. Distribution: 98% protein bound. Metabolism: Extensive hepatic metabolism. Elimination: Renal and fecal. Half-Life: 13–19 h.Nursing Implications
Assessment & Drug Effects
- Monitor for adverse effects of concurrently used drugs that have a narrow therapeutic window and are metabolized by CYP26D (e.g., flecainide, thioridazine, or TRICYCLIC ANTIDEPRESSANTS).
- Lab tests: Monitor blood levels of digoxin with concurrent therapy and assess for S&S of digoxin toxicity.
Patient & Family Education
- Follow directions for taking the drug (see ADMINISTRATION).
- Do not drive or engage in potentially hazardous activities until response to drug is known.
- Use caution in hot environments to minimize the risk of heat prostration.
- Report any of the following to a health care provider: difficulty passing urine, unexplained nausea, or persistent constipation.
Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; 
Canadian drug name; 
Prototype drug