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Risk of Urinary Retention
Enablex should be administered with caution to patients with clinically significant bladder outflow obstruction because of the risk of urinary retention.
Decreased Gastrointestinal Motility
Enablex should be administered with caution to patients with gastrointestinal obstructive disorders because of the risk of gastric retention. Enablex, like other anticholinergic drugs, may decrease gastrointestinal motility and should be used with caution in patients with conditions such as severe constipation, ulcerative colitis, and myasthenia gravis.
Controlled Narrow-Angle Glaucoma
Enablex should be used with caution in patients being treated for narrow-angle glaucoma and only where the potential benefits outweigh the risks.
Angioedema of the face, lips, tongue, and/or larynx have been reported with darifenacin. In some cases angioedema occurred after the first dose. Angioedema associated with upper airway swelling may be life threatening. If involvement of the tongue, hypopharynx, or larynx occurs, darifenacin should be promptly discontinued and appropriate therapy and/or measures necessary to ensure a patent airway should be promptly provided.
Central Nervous System Effects
Enablex is associated with anticholinergic central nervous system (CNS) effects [see ADVERSE REACTIONS]. A variety of CNS anticholinergic effects have been reported, including headache, confusion, hallucinations and somnolence. Patients should be monitored for signs of anticholinergic CNS effects, particularly after beginning treatment or increasing the dose. Advise patients not to drive or operate heavy machinery until they know how Enablex affects them. If a patient experiences anticholinergic CNS effects, dose reduction or drug discontinuation should be considered.
Patients with Hepatic Impairment
The daily dose of Enablex should not exceed 7.5 mg for patients with moderate hepatic impairment (Child-Pugh B). Enablex has not been studied in patients with severe hepatic impairment (Child-Pugh C) and therefore is not recommended for use in this patient population [see DOSAGE AND ADMINISTRATION, Use In Specific Populations and CLINICAL PHARMACOLOGY].
Patient Counseling Information
“See FDA-approved patient labeling (PATIENT INFORMATION)”
Patients should be informed that anticholinergic agents, such as Enablex, may produce clinically significant adverse effects related to anticholinergic pharmacological activity including constipation, urinary retention and blurred vision. Heat prostration (due to decreased sweating) can occur when anticholinergics such as Enablex are used in a hot environment. Because anticholinergics, such as Enablex, may produce dizziness or blurred vision, patients should be advised to exercise caution in decisions to engage in potentially dangerous activities until the drug's effects have been determined. Patients should read the patient information leaflet before starting therapy with Enablex.
Patients should be informed that darifenacin may produce clinically significant angioedema that may result in airway obstruction. Patients should be advised to promptly discontinue darifenacin therapy and seek immediate medical attention if they experience edema of the tongue or laryngopharynx, or difficulty breathing.
Enablex extended-release tablets should be taken once daily with water. They may be taken with or without food, and should be swallowed whole and not chewed, divided or crushed.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Carcinogenicity studies with darifenacin were conducted in mice and rats. No evidence of drug-related carcinogenicity was revealed in a 24-month study in mice at dietary doses up to 100 mg/kg/day or approximately 32 times the estimated free plasma AUC reached at the maximum recommended human dose (the AUC at the MRHD) of 15 mg and in a 24-month study in rats at doses up to 15 mg/kg/day or up to approximately 12 times the AUC at the MRHD in female rats and approximately eight times the AUC at the MRHD in male rats.
There was no evidence for effects on fertility in male or female rats treated at oral doses up to approximately 78 times (50 mg/kg/day) the AUC at the MRHD.
Use In Specific Populations
Pregnancy Category C
There are no studies of darifenacin in pregnant women.
Darifenacin was not teratogenic in rats and rabbits at plasma exposures of free drug (via AUC) up to 59 times and 28 times, respectively (doses up to 50 and 30 mg/kg/day, respectively) the maximum recommended human dose [MRHD] of 15 mg. At approximately 59 times the MRHD in rats, there was a delay in the ossification of the sacral and caudal vertebrae which was not observed at approximately 13 times the AUC. Dystocia was observed in dams at approximately 17 times the AUC (10 mg/kg/day). Slight developmental delays were observed in pups at this dose. At five times the AUC (3 mg/kg/day), there were no effects on dams or pups. In rabbits, an exposure approximately 28 times (30 mg/kg/day) the MRHD of darifenacin was shown to increase post-implantation loss, with a no effect level at nine times (10 mg/kg/day) the AUC at the MRHD. Dilated ureter and/or kidney pelvis was also observed in offspring at this dose along with urinary bladder dilation consistent with the pharmacological action of darifenacin, with one case observed at nine times (10 mg/kg/day). No effect was observed at approximately 2.8 times (3 mg/kg/day) the AUC at the MRHD.
Because animal reproduction studies are not always predictive of human response, Enablex should be used during pregnancy only if the benefit to the mother outweighs the potential risk to the fetus.
Darifenacin is excreted into the milk of rats. It is not known whether darifenacin is excreted into human milk and therefore caution should be exercised before Enablex is administered to a nursing woman.
The safety and effectiveness of Enablex in pediatric patients have not been established.
In the fixed-dose, placebo-controlled, clinical studies, 30 percent of patients treated with Enablex were over 65 years of age. No overall differences in safety or efficacy were observed between patients over 65 years (n = 207) and younger patients < 65 years (n = 464). No dose adjustment is recommended for elderly patients [see CLINICAL PHARMACOLOGY and Clinical Studies].
Subjects with severe hepatic impairment (Child-Pugh C) have not been studied, therefore Enablex is not recommended for use in these patients [see DOSAGE AND ADMINISTRATION and WARNINGS AND PRECAUTIONS]. The daily dose of Enablex should not exceed 7.5 mg once daily for patients with moderate hepatic impairment (Child-Pugh B) [see DOSAGE AND ADMINISTRATION and WARNINGS AND PRECAUTIONS]. After adjusting for plasma protein binding, unbound darifenacin exposure was estimated to be 4.7-fold higher in subjects with moderate hepatic impairment than subjects with normal hepatic function. No dose adjustment is recommended for patients with mild hepatic impairment (Child-Pugh A).
A study of subjects with varying degrees of renal impairment (creatinine clearance between 10 and 136 mL/min) demonstrated no clear relationship between renal function and darifenacin clearance. No dose adjustment is recommended for patients with renal impairment [see CLINICAL PHARMACOLOGY].
Last reviewed on RxList: 3/22/2012
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