Tamsulosin

12.1 Mechanism of Action The symptoms associated with benign prostatic hyperplasia (BPH) are related to bladder outlet obstruction, which is comprised of two underlying components: static and dynamic. The static component is related to an increase in prostate size caused, in part, by a proliferation of smooth muscle cells in the prostatic stroma. However, the severity of BPH symptoms and the degree of urethral obstruction do not correlate well with the size of the prostate. The dynamic component is a function of an increase in smooth muscle tone in the prostate and bladder neck leading to constriction of the bladder outlet. Smooth muscle tone is mediated by the sympathetic nervous stimulation of alpha 1 adrenoceptors, which are abundant in the prostate, prostatic capsule, prostatic urethra, and bladder neck. Blockade of these adrenoceptors can cause smooth muscles in the bladder neck and prostate to relax, resulting in an improvement in urine flow rate and a reduction in symptoms of BPH. Tamsulosin, an alpha 1 adrenoceptor blocking agent, exhibits selectivity for alpha 1 receptors in the human prostate. At least three discrete alpha 1 adrenoceptor subtypes have been identified: alpha 1A , alpha 1B , and alpha 1D ; their distribution differs between human organs and tissue. Approximately 70% of the alpha 1 receptors in the human prostate are of the alpha 1A subtype. Tamsulosin hydrochloride capsules are not intended for use as an antihypertensive drug.

1 INDICATIONS AND USAGE Tamsulosin hydrochloride capsules are indicated for the treatment of the signs and symptoms of benign prostatic hyperplasia (BPH) [see Clinical Studies (14)]. Tamsulosin hydrochloride capsules are not indicated for the treatment of hypertension. Tamsulosin hydrochloride capsules are an alpha 1 adrenoceptor antagonist indicated for treatment of the signs and symptoms of benign prostatic hyperplasia (1) Tamsulosin hydrochloride capsules are not indicated for the treatment of hypertension (1)

2 DOSAGE AND ADMINISTRATION Tamsulosin hydrochloride capsules 0.4 mg once daily is recommended as the dose for the treatment of the signs and symptoms of BPH. It should be administered approximately one-half hour following the same meal each day. Tamsulosin hydrochloride capsules should not be crushed, chewed or opened. For those patients who fail to respond to the 0.4 mg dose after 2 to 4 weeks of dosing, the dose of tamsulosin hydrochloride capsules can be increased to 0.8 mg once daily. Tamsulosin hydrochloride capsules 0.4 mg should not be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole) [see Warnings and Precautions (5.2)]. If tamsulosin hydrochloride capsules administration is discontinued or interrupted for several days at either the 0.4 mg or 0.8 mg dose, therapy should be started again with the 0.4 mg once-daily dose. 0.4 mg once daily taken approximately one-half hour following the same meal each day. Tamsulosin hydrochloride capsules should not be crushed, chewed or opened. (2) Can be increased to 0.8 mg once daily for patients who fail to respond to the 0.4 mg dose after 2 to 4 weeks of dosing (2) If discontinued or interrupted for several days, therapy should start again with the 0.4 mg once-daily dose (2)

6 ADVERSE REACTIONS The most common adverse events (≥2% of patients and at a higher incidence than placebo) with the 0.4 mg dose or 0.8 mg dose were headache, dizziness, rhinitis, infection, abnormal ejaculation, asthenia, back pain, diarrhea, pharyngitis, chest pain, cough increased, somnolence, nausea, sinusitis, insomnia, libido decreased, tooth disorder, and blurred vision (6.1) To report SUSPECTED ADVERSE REACTIONS, contact XLCare Pharmaceuticals, Inc. at 1-866-495-1995 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical studies are conducted under widely varying conditions, adverse reactions rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice. The incidence of treatment-emergent adverse events has been ascertained from six short-term U.S. and European placebo-controlled clinical trials in which daily doses of 0.1 to 0.8 mg tamsulosin hydrochloride capsules were used. These studies evaluated safety in 1783 patients treated with tamsulosin hydrochloride capsules and 798 patients administered placebo. Table 1 summarizes the treatment-emergent adverse events that occurred in ≥2% of patients receiving either tamsulosin hydrochloride capsules 0.4 mg or 0.8 mg and at an incidence numerically higher than that in the placebo group during two 13-week U.S. trials (US92-03A and US93-01) conducted in 1487 men. Table 1 Treatment-Emergent* Adverse Events Occurring in ≥2% of Tamsulosin Hydrochloride Capsules or Placebo Patients in Two U.S. Short-Term Placebo-Controlled Clinical Studies BODY SYSTEM/ ADVERSE EVENT TAMSULOSIN HYDROCHLORIDE CAPSULES GROUPS PLACEBO 0.4 mg n=502 0.8 mg n=492 n=493 BODY AS WHOLE Headache 97 (19.3%) 104 (21.1%) 99 (20.1%) Infection† 45 (9%) 53 (10.8%) 37 (7.5%) Asthenia 39 (7.8%) 42 (8.5%) 27 (5.5%) Back pain 35 (7%) 41 (8.3%) 27 (5.5%) Chest pain 20 (4%) 20 (4.1%) 18 (3.7%) NERVOUS SYSTEM Dizziness 75 (14.9%) 84 (17.1%) 50 (10.1%) Somnolence 15 (3%) 21 (4.3%) 8 (1.6%) Insomnia 12 (2.4%) 7 (1.4%) 3 (0.6%) Libido decreased 5 (1%) 10 (2%) 6 (1.2%) RESPIRATORY SYSTEM Rhinitis‡ 66 (13.1%) 88 (17.9%) 41 (8.3%) Pharyngitis 29 (5.8%) 25 (5.1%) 23 (4.7%) Cough increased 17 (3.4%) 22 (4.5%) 12 (2.4%) Sinusitis 11 (2.2%) 18 (3.7%) 8 (1.6%) DIGESTIVE SYSTEM Diarrhea 31 (6.2%) 21 (4.3%) 22 (4.5%) Nausea 13 (2.6%) 19 (3.9%) 16 (3.2%) Tooth disorder 6 (1.2%) 10 (2%) 7 (1.4%) UROGENITAL SYSTEM Abnormal ejaculation 42 (8.4%) 89 (18.1%) 1 (0.2%) SPECIAL SENSES Blurred vision 1 (0.2%) 10 (2%) 2 (0.4%) * A treatment-emergent adverse event was defined as any event satisfying one of the following criteria: The adverse event occurred for the first time after initial dosing with double-blind study medication; The adverse event was present prior to or at the time of initial dosing with double-blind study medication and subsequently increased in severity during double-blind treatment; or The adverse event was present prior to or at the time of initial dosing with double-blind study medication, disappeared completely, and then reappeared during double-blind treatment. † Coding preferred terms also include cold, common cold, head cold, flu, and flu-like symptoms. ‡ Coding preferred terms also include nasal congestion, stuffy nose, runny nose, sinus congestion, and hay fever. Signs and Symptoms of Orthostasis In the two U.S. studies, symptomatic postural hypotension was reported by 0.2% of patients (1 of 502) in the 0.4 mg group, 0.4% of patients (2 of 492) in the 0.8 mg group, and by no patients in the placebo group. Syncope was reported by 0.2% of patients (1 of 502) in the 0.4 mg group, 0.4% of patients (2 of 492) in the 0.8 mg group, and 0.6% of patients (3 of 493) in the placebo group. Dizziness was reported by 15% of patients (75 of 502) in the 0.4 mg group, 17% of patients (84 of 492) in the 0.8 mg group, and 10% of patients (50 of 493) in the placebo group. Vertigo was reported by 0.6% of patients (3 of 502) in the 0.4 mg group, 1% of patients (5 of 492) in the 0.8 mg group, and by 0.6% of patients (3 of 493) in the placebo group. Multiple testing for orthostatic hypotension was conducted in a number of studies. Such a test was considered positive if it met one or more of the following criteria: (1) a decrease in systolic blood pressure of ≥20 mmHg upon standing from the supine position during the orthostatic tests; (2) a decrease in diastolic blood pressure ≥10 mmHg upon standing, with the standing diastolic blood pressure <65 mmHg during the orthostatic test; (3) an increase in pulse rate of ≥20 bpm upon standing with a standing pulse rate ≥100 bpm during the orthostatic test; and (4) the presence of clinical symptoms (faintness, lightheadedness/lightheaded, dizziness, spinning sensation, vertigo, or postural hypotension) upon standing during the orthostatic test. Following the first dose of double-blind medication in Study 1, a positive ort

7 DRUG INTERACTIONS • Tamsulosin hydrochloride capsules 0.4 mg should not be used with strong inhibitors of CYP3A4 (e.g., ketoconazole). Tamsulosin hydrochloride capsules should be used with caution in combination with moderate inhibitors of CYP3A4 (e.g., erythromycin), in combination with strong (e.g., paroxetine) or moderate (e.g., terbinafine) inhibitors of CYP2D6, or in patients known to be CYP2D6 poor metabolizers, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg). ( 5.2 , 7.1 , 12.3 ) • Concomitant use of PDE5 inhibitors with tamsulosin can potentially cause symptomatic hypotension ( 5.2 , 7.3 , 12.3 ). 7.1 Cytochrome P450 Inhibition Strong and Moderate Inhibitors of CYP3A4 or CYP2D6 Tamsulosin is extensively metabolized, mainly by CYP3A4 and CYP2D6. Concomitant treatment with ketoconazole (a strong inhibitor of CYP3A4) resulted in an increase in the C max and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. The effects of concomitant administration of a moderate CYP3A4 inhibitor (e.g., erythromycin) on the pharmacokinetics of tamsulosin hydrochloride have not been evaluated [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. Concomitant treatment with paroxetine (a strong inhibitor of CYP2D6) resulted in an increase in the C max and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. A similar increase in exposure is expected in CYP2D6 poor metabolizers (PM) as compared to extensive metabolizers (EM). Since CYP2D6 PMs cannot be readily identified and the potential for significant increase in tamsulosin exposure exists when tamsulosin hydrochloride capsules 0.4 mg is coadministered with strong CYP3A4 inhibitors in CYP2D6 PMs, tamsulosin hydrochloride capsules 0.4 mg should not be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole) [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. The effects of concomitant administration of a moderate CYP2D6 inhibitor (e.g., terbinafine) on the pharmacokinetics of tamsulosin hydrochloride have not been evaluated [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. The effects of coadministration of both a CYP3A4 and a CYP2D6 inhibitor with tamsulosin hydrochloride capsules have not been evaluated. However, there is a potential for significant increase in tamsulosin exposure when tamsulosin hydrochloride capsules 0.4 mg is coadministered with a combination of both CYP3A4 and CYP2D6 inhibitors [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. Cimetidine Treatment with cimetidine resulted in a significant decrease (26%) in the clearance of tamsulosin hydrochloride, which resulted in a moderate increase in tamsulosin hydrochloride AUC (44%) [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. 7.2 Other Alpha Adrenergic Blocking Agents The pharmacokinetic and pharmacodynamic interactions between tamsulosin hydrochloride capsules and other alpha adrenergic blocking agents have not been determined; however, interactions between tamsulosin hydrochloride capsules and other alpha adrenergic blocking agents may be expected [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. 7.3 PDE5 Inhibitors Caution is advised when alpha adrenergic blocking agents including tamsulosin hydrochloride are coadministered 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 Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. 7.4 Warfarin A definitive drug-drug interaction study between tamsulosin hydrochloride and warfarin was not conducted. Results from limited in vitro and in vivo studies are inconclusive. Caution should be exercised with concomitant administration of warfarin and tamsulosin hydrochloride capsules [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. 7.5 Nifedipine, Atenolol, Enalapril Dosage adjustments are not necessary when tamsulosin hydrochloride capsules are administered concomitantly with nifedipine, atenolol, or enalapril [see Clinical Pharmacology (12.3)]. 7.6 Digoxin and Theophylline Dosage adjustments are not necessary when a tamsulosin hydrochloride capsules are administered concomitantly with digoxin or theophylline [see Clinical Pharmacology (12.3)]. 7.7 Furosemide Tamsulosin hydrochloride capsules had no effect on the pharmacodynamics (excretion of electrolytes) of furosemide. While furosemide produced an 11% to 12% reduction in tamsulosin hydrochloride C max and AUC, these changes are expected to be clinically insignificant and do not require adjustment of the tamsulosin hydrochloride capsules dosage [see Clinical Pharmacology (12.3)].