Darifenacin Hydrobromide

1 INDICATIONS AND USAGE Darifenacin extended-release tablets are muscarinic antagonist indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency and frequency. Darifenacin is a muscarinic antagonist indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency and frequency. ( 1 )

2 DOSAGE AND ADMINISTRATION The recommended starting dose of darifenacin extended-release tablets is 7.5 mg once daily. Based upon individual response, the dose may be increased to 15 mg once daily, as early as two weeks after starting therapy. Darifenacin extended-release tablets should be taken once daily with water. Darifenacin extended-release tablets may be taken with or without food, and should be swallowed whole and not chewed, divided or crushed. For patients with moderate hepatic impairment (Child-Pugh B) or when co-administered with potent CYP3A4 inhibitors (for example, ketoconazole, itraconazole, ritonavir, nelfinavir, clarithromycin and nefazadone), the daily dose of darifenacin extended-release tablets should not exceed 7.5 mg. Darifenacin extended-release tablets are not recommended for use in patients with severe hepatic impairment (Child-Pugh C) [see Warnings & Precautions (5.6) , Drug Interactions (7.1) , Use in Specific Populations (8.6) and Clinical Pharmacology (12.3) ] . The recommended starting dose of darifenacin extended-release tablets is 7.5 mg once daily. Based upon individual response, the dose may be increased to 15 mg once daily, as early as two weeks after starting therapy. ( 2 ) The daily dose of darifenacin extended-release tablets should not exceed 7.5 mg in the following patients: • Patients with moderate hepatic impairment (Child-Pugh B) ( 2 , 8.6 ) • Patients taking potent CYP3A4 inhibitors ( 2 , 7.1 ) Darifenacin extended-release tablets are not recommended for use in patients with severe hepatic impairment (Child-Pugh C). ( 2 , 8.6 ) Darifenacin extended-release tablets may be taken with or without food. The tablet should be swallowed whole with water and not chewed, divided or crushed. ( 2 )

6 ADVERSE REACTIONS The most frequently reported adverse reactions (>3 percent) for darifenacin are: constipation, dry mouth, headache, dyspepsia, nausea, urinary tract infection, accidental injury, and flu symptoms. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Polygen Pharmaceuticals Inc. at 1-888-291-7337 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety of darifenacin was evaluated in controlled clinical trials in a total of 8,830 patients, 6,001 of whom were treated with darifenacin. Of this total, 1,069 patients participated in three, 12-week, randomized, placebo-controlled, fixed-dose efficacy and safety studies (Studies 1, 2 and 3). Of this total, 337 and 334 patients received darifenacin 7.5 mg daily and 15 mg daily, respectively. In all long-term trials combined, 1,216 and 672 patients received treatment with darifenacin for at least 24 and 52 weeks, respectively. In Studies 1, 2 and 3 combined, the serious adverse reactions to darifenacin were urinary retention and constipation. In Studies 1, 2 and 3 combined, dry mouth leading to study discontinuation occurred in 0 percent, 0.9 percent, and 0 percent of patients treated with darifenacin 7.5 mg daily, darifenacin 15 mg daily and placebo, respectively. Constipation leading to study discontinuation occurred in 0.6 percent, 1.2 percent, and 0.3 percent of patients treated with darifenacin 7.5 mg daily, darifenacin 15 mg daily and placebo, respectively. Table 1 lists the rates of identified adverse reactions, derived from all reported adverse events in 2 percent or more of patients treated with 7.5 mg or 15 mg darifenacin, and greater than placebo in Studies 1, 2 and 3. In these studies, the most frequently reported adverse reactions were dry mouth and constipation. The majority of the adverse reactions were mild or moderate in severity and most occurred during the first two weeks of treatment. Table 1: Incidence of Identified Adverse Reactions, Derived from All Adverse Events Reported in ≥2 Percent of Patients Treated with Darifenacin Extended-Release Tablets and More Frequent with Darifenacin than with Placebo in Studies 1, 2, and 3 Body System Adverse Reaction Percentage of Subjects Darifenacin 7.5 mg N = 337 Darifenacin 15 mg N = 334 Placebo N = 388 Digestive Dry Mouth 20.2 35.3 8.2 Constipation 14.8 21.3 6.2 Dyspepsia 2.7 8.4 2.6 Abdominal Pain 2.4 3.9 0.5 Nausea 2.7 1.5 1.5 Diarrhea 2.1 0.9 1.8 Urogenital Urinary Tract Infection 4.7 4.5 2.6 Nervous Dizziness 0.9 2.1 1.3 Body as whole Asthenia 1.5 2.7 1.3 Eye Dry Eyes 1.5 2.1 0.5 Other adverse reactions reported by 1 percent to 2 percent of darifenacin-treated patients include: abnormal vision, accidental injury, back pain, dry skin, flu syndrome, hypertension, vomiting, peripheral edema, weight gain, arthralgia, bronchitis, pharyngitis, rhinitis, sinusitis, rash, pruritus, urinary tract disorder and vaginitis. Study 4 was a randomized, 12-week, placebo-controlled, dose-titration regimen study in which darifenacin was administered in accordance with dosing recommendations [see Dosage and Administration (2) ] . All patients initially received placebo or darifenacin 7.5 mg daily, and after two weeks, patients and physicians were allowed to adjust upward to darifenacin 15 mg if needed. In this study, the most commonly reported adverse reactions were also constipation and dry mouth. Table 2 lists the identified adverse reactions, derived from all adverse events reported in >3 percent of patients treated with darifenacin and greater than placebo. Table 2: Number (Percent) of Adverse Reactions, Derived from All Adverse Events Reported in >3 Percent of Patients Treated with Darifenacin Extended-Release Tablets, and More Frequent with Darifenacin than Placebo, in Study 4 Adverse Reaction Darifenacin 7.5 mg/15 mg N = 268 Placebo N = 127 Constipation 56 (20.9 percent) 10 (7.9 percent) Dry Mouth 50 (18.7 percent) 11 (8.7 percent) Headache 18 (6.7 percent) 7 (5.5 percent) Dyspepsia 12 (4.5 percent) 2 (1.6 percent) Nausea 11 (4.1 percent) 2 (1.6 percent) Urinary Tract Infection 10 (3.7 percent) 4 (3.1 percent) Accidental Injury 8 (3.0 percent) 3 (2.4 percent) Flu Syndrome 8 (3.0 percent) 3 (2.4 percent) 6.2 Post Marketing Experience The following adverse reactions have been reported during post approval use of darifenacin extended-release tablets (darifenacin). Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate frequency or establish a causal relationship to drug exposure. Dermatologic: erythema multiforme, interstitial granuloma annulare General: hypersensitivity reactions, including angioedema with airway obstruction and anaphylactic reaction Central Nervous: confusion, hallucinations and somnolence Cardiovascular: palpitations and syncope

12.3 Pharmacokinetics Absorption After oral administration of darifenacin to healthy volunteers, peak plasma concentrations of darifenacin are reached approximately seven hours after multiple dosing and steady-state plasma concentrations are achieved by the sixth day of dosing. The mean (SD) steady-state time course of darifenacin 7.5 mg and 15 mg extended-release tablets is depicted in Figure 1. Figure 1: Mean (SD) Steady-State Darifenacin Plasma Concentration-Time Profiles for Darifenacin 7.5 mg and 15 mg in Healthy Volunteers Including Both CYP2D6 EMs and PMs * A summary of mean (standard deviation, SD) steady-state pharmacokinetic parameters of darifenacin 7.5 mg and 15 mg extended-release tablets in EMs and PMs of CYP2D6 is provided in Table 3. Table 3: Mean (SD) Steady-State Pharmacokinetic Parameters from Darifenacin 7.5 mg and 15 mg Extended-Release Tablets Based on Pooled Data by Predicted CYP2D6 Phenotype Darifenacin 7.5 mg (N = 68 EM, 5 PM) Darifenacin 15 mg (N = 102 EM, 17 PM) AUC 2 4 ( ng • h / mL ) C m a x ( ng / mL ) C a v g ( ng / mL ) T m a x ( h ) t 1 / 2 ( h ) AUC 2 4 ( ng • h / mL ) C m a x ( ng / mL ) C a v g ( ng / mL ) T m a x ( h ) t 1 / 2 ( h ) EM 29.24 (15.47) 2.01 (1.04) 1.22 (0.64) 6.49 (4.19) 12.43 (5.64) a 88.90 (67.87) 5.76 (4.24) 3.70 (2.83) 7.61 (5.06) 12.05 (12.37) b PM 67.56 (13.13) 4.27 (0.98) 2.81 (0.55) 5.20 (1.79) 19.95 c - 157.71 (77.08) 9.99 (5.09) 6.58 (3.22) 6.71 (3.58) 7.40 d - a N = 25; b N = 8; c N = 2; d N = 1; AUC 2 4 = Area under the plasma concentration versus time curve for 24h; C m a x = Maximum observed plasma concentration; C a v g = Average plasma concentration at steady-state; T m a x = Time of occurrence of C m a x ; t 1 / 2 = Terminal elimination half-life. Regarding EM and PM [see CLINICAL PHARMACOLOGY, Pharmacokinetics, Variability in Metabolism (12.3)]. The mean oral bioavailability of darifenacin in EMs at steady-state is estimated to be 15 percent and 19 percent for mg and 15 mg tablets, respectively. Effect of Food Following single dose administration of darifenacin with food, the AUC of darifenacin was not affected, while the C max was increased by 22 percent and T max was shortened by 3.3 hours. There is no effect of food on multiple-dose pharmacokinetics from darifenacin. Distribution Darifenacin is approximately 98 percent bound to plasma proteins (primarily to alpha-1-acid-glycoprotein). The steady-state volume of distribution (V ss ) is estimated to be 163 L. Metabolism Darifenacin is extensively metabolized by the liver following oral dosing. Metabolism is mediated by cytochrome P450 enzymes CYP2D6 and CYP3A4. The three main metabolic routes are as follows: (i) monohydroxylation in the dihydrobenzofuran ring; (ii) dihydrobenzofuran ring opening; (iii) N-dealkylation of the pyrrolidine nitrogen. The initial products of the hydroxylation and N-dealkylation pathways are the major circulating metabolites but they are unlikely to contribute significantly to the overall clinical effect of darifenacin. Variability in Metabolism A subset of individuals (approximately 7 percent Caucasians and 2 percent African Americans) are poor metabolizers (PMs) of CYP2D6 metabolized drugs. Individuals with normal CYP2D6 activity are referred to as extensive metabolizers (EMs). The metabolism of darifenacin in PMs will be principally mediated via CYP3A4. The darifenacin ratios (PM versus EM) for C max and AUC following darifenacin 15 mg once daily at steady-state were 1.9 and 1.7, respectively. Excretion Following administration of an oral dose of 14 C-darifenacin solution to healthy volunteers, approximately 60 percent of the radioactivity was recovered in the urine and 40 percent in the feces. Only a small percentage of the excreted dose was unchanged darifenacin (3 percent). Estimated darifenacin clearance is 40 L/h for EMs and 32 L/h for PMs. The elimination half-life of darifenacin following chronic dosing is approximately 13 to 19 hours. Drug-Drug Interactions Effects of Other Drugs on Darifenacin Darifenacin metabolism is primarily mediated by the cytochrome P450 enzymes CYP2D6 and CYP3A4. Therefore, inducers of CYP3A4 or inhibitors of either of these enzymes may alter darifenacin pharmacokinetics [see Drug Interactions (7) ] . CYP3A4 Inhibitors: In a drug interaction study, when a 7.5 mg once daily dose of darifenacin was given to steady-state and co-administered with the potent CYP3A4 inhibitor ketoconazole 400 mg, mean darifenacin Cmax increased to 11.2 ng/mL for EMs (n = 10) and 55.4 ng/mL for one PM subject (n = 1). Mean AUC increased to 143 and 939 ng • h/mL for EMs and for one PM subject, respectively. When a 15 mg daily dose of darifenacin was given with ketoconazole, mean darifenacin Cmax increased to 67.6 ng/mL and 58.9 ng/mL for EMs (n = 3) and one PM subject (n = 1), respectively. Mean AUC increased to 1,110 and 931 ng • h/mL for EMs and for one PM subject, respectively [see Dosage and Administration (2) and Drug Interactions (7.1) ] . The mean C max and AUC of darifenacin following 30 mg once daily dosing at steady-state were 128 percent and 95 percent higher, respectively, in the presence of a moderate CYP3A4 inhibitor, erythromycin. Co-administration of fluconazole, a moderate CYP3A4 inhibitor and darifenacin 30 mg once daily at steady-state increased darifenacin C max and AUC by 88 percent and 84 percent, respectively [see Drug Interactions (7.1) ] . The mean C max and AUC of darifenacin following 30 mg once daily at steady-state were 42 percent and 34 percent higher, respectively, in the presence of cimetidine, a mixed CYP P450 enzyme inhibitor. CYP2D6 Inhibitors: Darifenacin exposure following 30 mg once daily at steady-state was 33 percent higher in the presence of the potent CYP2D6 inhibitor paroxetine 20 mg [see Drug Interactions (7.2) ] . Effects of Darifenacin on Other Drugs In Vitro Studies: Based on in vitro human microsomal studies, darifenacin is not expected to inhibit CYP1A2 or CYP2C9 at clinically relevant concentrations. In Vivo Studies: The potential for clinical doses of darifenacin to act as inhibitors of CYP2D6 or CYP3A4 substrates was investigated in specific drug interaction studies. CYP2D6 Substrates: The mean C max and AUC of imipramine, a CYP2D6 substrate, were increased by 57 percent and 70 percent, respectively, in the presence of steady-state darifenacin 30 mg once daily. The mean C max and AUC of desipramine, the active metabolite of imipramine, were increased by 260 percent [see Drug Interactions (7.3) ] . CYP3A4 Substrates: Darifenacin (30 mg daily) co-administered with a single oral dose of midazolam 7.5 mg resulted in a 17 percent increase in midazolam exposure. Combination Oral Contraceptives: Darifenacin (10 mg three times daily) had no effect on the pharmacokinetics of a combination oral contraceptive containing levonorgestrel (0.15 mg) and ethinyl estradiol (0.03 mg). Warfarin: Darifenacin had no significant effect on prothrombin time when a single dose of warfarin 30 mg was co-administered with darifenacin (30 mg daily) at steady-state [see Drug Interactions (7.6) ] . Digoxin: Darifenacin (30 mg daily) co-administered with digoxin (0.25 mg) at steady-state resulted in a 16 percent increase in digoxin exposure [see Drug Interactions (7.7) ] . Pharmacokinetics in Special Populations Age: A population pharmacokinetic analysis of patient data indicated a trend for clearance of darifenacin to decrease with age (6 percent per decade relative to a median age of 44). Following administration of darifenacin 15 mg once daily, darifenacin exposure at steady-state was approximately 12 percent to 19 percent higher in volunteers between 45 and 65 years of age compared to younger volunteers aged 18 to 44 years [see Use in Specific Populations (8.5) ]. Pediatric: The pharmacokinetics of darifenacin has not been studied in the pediatric population [see Use in Specific Populations (8.4) ] . Gender: PK parameters were calculated for 22 male and 25 female healthy volunteers. Darifenacin C max and AUC at steady-state were approximately 57 percent to 79 percent and 61 percent to 73 percent higher in females than in males, respectively [see Use in Specific Populations (8.8) ] . Renal Impairment: A study of subjects with varying degrees of renal impairment (creatinine clearance between 10 and 136 mL/min) given darifenacin 15 mg once daily to steady-state demonstrated no clear relationship between renal function and darifenacin clearance [see Use in Specific Populations (8.7) ] . Hepatic Impairment: Darifenacin pharmacokinetics were investigated in subjects with mild (Child-Pugh A) or moderate (Child-Pugh B) impairment of hepatic function given darifenacin 15 mg once daily to steady-state. Mild hepatic impairment had no effect on the pharmacokinetics of darifenacin. However, protein binding of darifenacin was affected by moderate hepatic impairment. 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. Subjects with severe hepatic impairment (Child-Pugh C) have not been studied [see Dosage and Administration (2) , Warning and Precautions (5.5) and Use in Specific Population (8.6) ] . Image