Silodosin 8 mg Capsule, 30-count

5 WARNINGS AND PRECAUTIONS Postural hypotension, with or without symptoms (e.g., dizziness), may develop when beginning silodosin treatment. ( 5.1 ) In patients with moderate renal impairment, silodosin dose should be reduced to 4 mg once daily. ( 5.2 ) Silodosin should not be used in combination with other alpha-blockers.

( 5.5 ) Examine patients thought to have BPH prior to starting therapy with silodosin to rule out the presence of carcinoma of the prostate. ( 5.6 ) Inform patients planning cataract surgery to notify their ophthalmologist that they are taking silodosin because of the possibility of Intraoperative Floppy Iris Syndrome (IFIS). ( 5.7 )

5.1Orthostatic Effects Postural hypotension, with or without symptoms (e.g., dizziness) may develop when beginning silodosin treatment. As with other alpha-blockers, there is potential for syncope. Patients should be cautioned about driving, operating machinery, or performing hazardous tasks when initiating therapy [see Adverse Reactions (6) , Use in Specific Populations (8.5) , Clinical Pharmacology (12.2) , and Patient Counseling Information (17) ] .

5.2Renal Impairment In a clinical pharmacology study, plasma concentrations (AUC and C max ) of silodosin were approximately three times higher in subjects with moderate renal impairment compared with subjects with normal renal function, while half-lives of silodosin doubled in duration. The dose of silodosin should be reduced to 4 mg in patients with moderate renal impairment. Exercise caution and monitor such patients for adverse events [see Use in Specific Populations (8.6) and Clinical Pharmacology (12.3) ] .

Silodosin is contraindicated in patients with severe renal impairment [see Contraindications (4) ] .

5.3Hepatic Impairment Silodosin has not been tested in patients with severe hepatic impairment, and therefore, should not be prescribed to such patients [see Contraindications (4) , Use in Specific Populations (8.7) and Clinical Pharmacology (12.3) ] .

5.4Pharmacokinetic Drug-Drug Interactions In a drug interaction study, co-administration of a single 8 mg dose of silodosin with 400 mg ketoconazole, a strong CYP3A4 inhibitor, caused a 3.8-fold increase in maximum plasma silodosin concentrations and 3.2-fold increase in silodosin exposure (i.e. AUC). Concomitant use of ketoconazole or other strong CYP3A4 inhibitors (e.g., itraconazole, clarithromycin, ritonavir) is therefore contraindicated [see Drug Interactions (7.1) ] .

5.5Pharmacodynamic Drug-Drug Interactions The pharmacodynamic interactions between silodosin and other alpha-blockers have not been determined. However, interactions may be expected, and silodosin should not be used in combination with other alpha-blockers [see Drug Interactions (7.3) ] . A specific pharmacodynamic interaction study between silodosin and antihypertensive agents has not been performed.

However, patients in the Phase 3 clinical studies taking concomitant antihypertensive medications with silodosin did not experience a significant increase in the incidence of syncope, dizziness, or orthostasis. Nevertheless, exercise caution during concomitant use with antihypertensives and monitor patients for possible adverse events [see Adverse Reactions (6.1) and Drug Interactions (7.6) ] . Caution is also advised when alpha-adrenergic blocking agents including silodosin are co­-administered with PDE5 inhibitors.

Alpha-adrenergic blockers and PDE5 inhibitors are both vasodilators that can lower blood pressure. Concomitant use of these two drug classes can potentially cause symptomatic hypotension [see Drug Interactions (7.5) ] .

5.6Carcinoma of the Prostate Carcinoma of the prostate and BPH cause many of the same symptoms. These two diseases frequently co-exist. Therefore, patients thought to have BPH should be examined prior to starting therapy with silodosin to rule out the presence of carcinoma of the prostate.

5.7 Intraoperative Floppy Iris Syndrome Intraoperative Floppy Iris Syndrome has been…

6 ADVERSE REACTIONS Most common adverse reactions (incidence ≥ 2%) are retrograde ejaculation, dizziness, diarrhea, orthostatic hypotension, headache, nasopharyngitis, and nasal congestion. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Amneal Pharmaceuticals at 1-877-835-5472 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6.1Clinical 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 clinical practice. In U.S. clinical trials, 897 patients with BPH were exposed to 8 mg silodosin daily. This includes 486 patients exposed for 6 months and 168 patients exposed for 1 year.

The population was 44 to 87 years of age, and predominantly Caucasian. Of these patients, 42.8% were 65 years of age or older and 10.7% were 75 years of age or older. In double-blind, placebo controlled, 12-week clinical trials, 466 patients were administered silodosin and 457 patients were administered placebo.

At least one treatment-emergent adverse reaction was reported by 55.2% of silodosin treated patients (36.8% for placebo treated). The majority (72.1%) of adverse reactions for the silodosin treated patients (59.8% for placebo treated) were qualified by the investigator as mild. A total of 6.4% of silodosin treated patients (2.2% for placebo treated) discontinued therapy due to an adverse reaction (treatment-emergent), the most common reaction being retrograde ejaculation (2.8%) for silodosin treated patients.

Retrograde ejaculation is reversible upon discontinuation of treatment. Adverse Reactions observed in at least 2% of patients: The incidence of treatment-emergent adverse reactions listed in the following table were derived from two 12-week, multicenter, double-blind, placebo-controlled clinical studies of silodosin 8 mg daily in BPH patients. Adverse reactions that occurred in at least 2% of patients treated with silodosin and more frequently than with placebo are shown in Table 1.

Table 1: Adverse Reactions Occurring in ≥ 2% of Patients in 12-week, Placebo-Controlled Clinical Trials Adverse Reactions Silodosin N = 466 n (%) Placebo N = 457 n (%) Retrograde Ejaculation 131 (28.1) 4 (0.9) Dizziness 15 (3.2) 5 (1.1) Diarrhea 12 (2.6) 6 (1.3) Orthostatic Hypotension 12 (2.6) 7 (1.5) Headache 11 (2.4) 4 (0.9) Nasopharyngitis 11 (2.4) 10 (2.2) Nasal Congestion 10 (2.1) 1 (0.2) In the two 12-week, placebo-controlled clinical trials, the following adverse events were reported by between 1% and 2% of patients receiving silodosin and occurred more frequently than with placebo: insomnia, PSA increased, sinusitis, abdominal pain, asthenia, and rhinorrhea.

One case of syncope in a patient taking prazosin concomitantly and one case of priapism were reported in the silodosin treatment group. In a 9-month open-label safety study of silodosin, one case of Intraoperative Floppy Iris Syndrome (IFIS) was reported.

6.2Postmarketing Experience The following adverse reactions have been identified during post approval use of silodosin. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure: Skin and subcutaneous tissue disorders: toxic skin eruption, purpura, skin rash, pruritus, and urticaria Hepatobiliary disorders: jaundice, impaired hepatic function associated with increased transaminase values Immune system disorders: allergic-type reactions, not limited to skin reactions including swollen tongue and pharyngeal edema resulting in serious outcomes.

7 DRUG INTERACTIONS Strong P-glycoprotein inhibitors (e.g., cyclosporine): Co-administration may increase plasma silodosin concentration. Concomitant use is not recommended. ( 7.2 ) Alpha-blockers: Interactions involving concomitant use have not been determined.

However, interactions are expected and concomitant use is not recommended. ( 7.3 ) Concomitant use of PDE5 inhibitors with alpha-blockers including silodosin can potentially cause symptomatic hypotension. ( 5.5 , 7.5 )

7.1Moderate and Strong CYP3A4 Inhibitors In a clinical metabolic inhibition study, a 3.8-fold increase in silodosin maximum plasma concentrations and 3.2-fold increase in silodosin exposure were observed with concurrent administration of a strong CYP3A4 inhibitor, 400 mg ketoconazole. Use of strong CYP3A4 inhibitors such as itraconazole or ritonavir may cause plasma concentrations of silodosin to increase. Concomitant administration of strong CYP3A4 inhibitors and silodosin is contraindicated [see Contraindications (4) , Warnings and Precautions (5.4) and Clinical Pharmacology (12.3) ] .

The effect of moderate CYP3A4 inhibitors on the pharmacokinetics of silodosin has not been evaluated. Concomitant administration with moderate CYP3A4 inhibitors (e.g., diltiazem, erythromycin, verapamil) may increase concentration of silodosin. Exercise caution and monitor patients for adverse events when co-administering silodosin with moderate CYP3A4 inhibitors.

7.2Strong P-glycoprotein (P-gp) Inhibitors In vitro studies indicated that silodosin is a P-gp substrate. Ketoconazole, a CYP3A4 inhibitor that also inhibits P-gp, caused significant increase in exposure to silodosin. Inhibition of P-gp may lead to increased silodosin concentration. Silodosin is therefore not recommended in patients taking strong P-gp inhibitors such as cyclosporine [see Clinical Pharmacology (12.3) ] .

7.3Alpha-Blockers The pharmacodynamic interactions between silodosin and other alpha-blockers have not been determined. However, interactions may be expected, and silodosin should not be used in combination with other alpha-blockers [see Warnings and Precautions (5.5) ] .

7.4Digoxin The effect of co-administration of silodosin and digoxin 0.25 mg/day for 7 days was evaluated in a clinical trial in 16 healthy males, aged 18 to 45 years. Concomitant administration of silodosin and digoxin did not significantly alter the steady-state pharmacokinetics of digoxin. No dose adjustment is required.

7.5PDE5 Inhibitors Co-administration of silodosin with a single dose of 100 mg sildenafil or 20 mg tadalafil was evaluated in a placebo-controlled clinical study that included 24 healthy male subjects, 45 to 78 years of age. Orthostatic vital signs were monitored in the 12-hour period following concomitant dosing. During this period, the total number of positive orthostatic test results was greater in the group receiving silodosin plus a PDE5 inhibitor compared with silodosin alone.

No events of symptomatic orthostasis or dizziness were reported in subjects receiving silodosin with a PDE5 inhibitor.

7.6Other Concomitant Drug Therapy Antihypertensives The pharmacodynamic interactions between silodosin and antihypertensives have not been rigorously investigated in a clinical study. However, approximately one-third of the patients in clinical studies used concomitant antihypertensive medications with silodosin. The incidence of dizziness and orthostatic hypotension in these patients was higher than in the general silodosin population (4.6% versus 3.8% and 3.4% versus 3.2%, respectively).

Exercise caution during concomitant use with antihypertensives and monitor patients for possible adverse events [see Warnings and Precautions (5.5) ] . Metabolic Interactions In vitro data indicate that silodosin does not have the potential to inhibit or induce cytochrome P450 enzyme systems.

7.7Food Interactions The effect of a moderate fat, moderate calorie meal on silodosin pharmacokinetics was variable and decreased s…