Brands, Medical Use, Clinical Data
- Extended-release tablets (containing 7.5 mg or 15 mg darifenacin as hydrobromide salt)
Brands / Synonyms
For the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency and frequency.
Darifenacin is a competitive muscarinic receptor antagonist. In vitro studies using human recombinant muscarinic receptor subtypes show that darifenacin has greater affinity for the M3 receptor than for the other known muscarinic receptors (9 and 12-fold greater affinity for M3 compared to M1 and M5, respectively, and 59-fold greater affinity for M3 compared to both M2 and M4). Muscarinic receptors play an important role in several major cholinergically mediated functions, including contractions of the urinary bladder smooth muscle and stimulation of salivary secretion. Adverse drug effects such as dry mouth, constipation and abnormal vision may be mediated through effects on M3 receptors in these organs.
Mechanism of Action
Darifenacin selectively antagonizes the muscarinic M3 receptor. M3 receptors are involved in contraction of human bladder and gastrointestinal smooth muscle, saliva production, and iris sphincter function.
The mean oral bioavailability at steady state is estimated to be 15% and 19% for 7.5 mg and 15 mg tablets, respectively.
Overdosage can potentially result in severe central anticholinergic effects.
Biotrnasformation / Drug Metabolism
Hepatic. Primarily mediated by the cytochrome P450 enzymes CYP2D6 and CYP3A4.
ENABLEX® (darifenacin) extended-release tablets are contraindicated in patients with urinary
retention, gastric retention or uncontrolled narrow-angle glaucoma and in patients who are at risk for these
conditions. ENABLEX is also contraindicated in patients with known hypersensitivity to the drug or its
The daily dose of ENABLEX should not exceed 7.5 mg when coadministered with potent CYP3A4 inhibitors (e.g.,
ketoconazole, itraconazole, ritonavir, nelfinavir, clarithromycin and nefazadone) . Caution should be taken when
ENABLEX is used concomitantly with medications that are predominantly metabolized by CYP2D6 and which have a narrow
therapeutic window, such as flecainide, thioridazine and tricyclic antidepressants (see CLINICAL
PHARMACOLOGY). The concomitant use of ENABLEX with other anticholinergic agents may increase the frequency and/or
severity of dry mouth, constipation, blurred vision and other anticholinergic pharmacological effects.
Anticholinergic agents may potentially alter the absorption of some concomitantly administered drugs due to effects
on gastrointestinal motility.
Drug Laboratory Test Interactions
Interactions between darifenacin and laboratory tests have not been studied.