darifenacin

Therapeutic Classification: urinary tract antispasmodics

Pharmacologic Classification: anticholinergics

Indications ⬆ ⬇

REMS

Overactive bladder with symptoms (urge incontinence, urgency, frequency).

Action ⬆ ⬇

Acts as a muscarinic (cholinergic) receptor antagonist; antagonizes bladder smooth muscle contraction.

Therapeutic effects:

Decreased symptoms of overactive bladder.

Pharmacokinetics ⬆ ⬇

Absorption: 15–19% absorbed.

Distribution: Unknown.

Protein Binding: 98%.

Metabolism/Excretion: Extensively metabolized in the liver by the CYP2D6 isoenzyme, with some metabolism by the CYP3A4 isoenzyme; the CYP2D6 isoenzyme exhibits genetic polymorphism (∼7% of population may be poor metabolizers and may have significantly ↑ darifenacin concentrations and an ↑ risk of adverse effects). 60% excreted by the kidneys as metabolites, 40% in feces as metabolites.

Half-Life: 13–19 hr.

Time/Action Profile ⬆ ⬇

ROUTE	ONSET	PEAK	DURATION
PO	unknown	7 hr	24 hr

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Urinary retention;
Gastric retention;
Uncontrolled angle-closure glaucoma;
Severe hepatic impairment.

Use Cautiously in:

Moderate hepatic impairment (lower dose recommended);
Bladder outflow obstruction;
GI obstructive disorders, ↓ GI motility, severe constipation or ulcerative colitis;
Myasthenia gravis;
Angle-closure glaucoma;
OB: Safety not established in pregnancy;
Lactation: Safety not established in breastfeeding;
Pedi: Safety and effectiveness not established in children.

Adv. Reactions/Side Effects ⬆ ⬇

EENT: blurred vision

GI: constipation, dry mouth, dyspepsia, nausea

Metab: heat intolerance

Neuro: confusion, dizziness, drowsiness, hallucinations, headache

Misc: ANGIOEDEMA

Interactions ⬆ ⬇

Drug-drug:

Strong CYP3A4 inhibitors, including ketoconazole, itraconazole, ritonavir, nelfinavir, clarithromycin, and nefazodone may ↑ levels and risk of toxicity; daily dose should not exceed 7.5 mg.
Concurrent use of moderate CYP3A4 inhibitors, especially those with narrow therapeutic indices, including flecainide, thioridazine, and tricyclic antidepressants, should be undertaken with caution.

Route/Dosage ⬆ ⬇

PO (Adults ): 7.5 mg once daily, may ↑ after 2 wk to 15 mg once daily.

Availability ⬆ ⬇

(Generic available)

Extended-release tablets: 7.5 mg; 15 mg

Assessment ⬆ ⬇

Monitor voiding pattern and assess symptoms of overactive bladder (urinary urgency, urinary incontinence, urinary frequency) to and periodically during therapy.

Implementation ⬆ ⬇

PO: Administer once daily without regard to food. DNC: Swallow extended-release tablets whole; do not break, crush, or chew.

Patient/Family Teaching ⬆ ⬇

Instruct patient to take darifenacin as directed. If a dose is missed, skip dose and take next day; do not take 2 doses in same day. Advise patient to read Patient Information before starting therapy and with each Rx refill in case of changes.
Do not share darifenacin with others; may be dangerous.
Inform patient of potential anticholinergic side effects (constipation, urinary retention, blurred vision, heat prostration in a hot environment).
May cause dizziness, drowsiness, confusion, and blurred vision. Caution patient to avoid driving and other activities that require alertness until response to medication is known.
Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and consult health care professional before taking any new medications.
Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

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Pronunciation ⬇

Classifications ⬆ ⬇