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美国FDA首次核准坦索罗辛缓释胶囊用于前列腺增生症 美国食品药物管理局（FDA）的首次核准坦索罗辛盐酸的俗名药，一种0.4毫克的胶囊（Impax实验室公司，商品名Flomax，安斯泰来制药公司，勃林格殷格翰制药公司行销）。 FDA的俗名药办公室主任加里比勒医师在该局的新闻稿中表示，核准坦索罗辛的俗名药可以让良性前列腺肥大有更广泛的治疗选项，FDA的承诺提供俗名药物给病患使用，且这些药物符合和原商品名药物相同严格的标准。 坦索每天服用一次，每次剂量0.4 - 0.8毫克，餐后约30分钟时服用。 其他在部分病患发生过的副作用，包括在白内障手术和阴茎持续勃起症（勃起）手术时发生的术中跳动虹膜症候群（术软盘虹膜症）。 Company: Boehringer Ingelheim 勃林格殷格翰 适应症 用于治疗前列腺增生所致的异常排尿症状，如尿频、夜尿增多、排尿困难等。由于本品是通过改善尿道、膀胱颈及前列腺部位平滑肌功能而达到治疗目的，并非缩小增生腺体，故适用于轻、中度患者及未导致严重排尿障碍者，如已发生严重尿潴留时不应单独服用本品。 用法用量 成人每日 1 次，每次 0.4mg ，饭后口服。根据年龄、症状的不同可适当增减。 一般无严重不良反应，偶可出现头晕及蹒跚感，多可自愈。极少数人偶可出现皮疹，需停药。少数人有胃肠道不适，饭后服药多可避免。 对本品有过敏史者禁用。 1.本品主要针对尿道、膀胱颈及前列腺平滑肌，并无缩小前列腺体积之作用，如前列腺体积过大，梗阻症状明显时，要与 5 α 原酶抑制剂同时服用，待 3-6 个月前列腺体积明显缩小后，再根据症状决定服药与否。
Flomax 1 INDICATIONS AND USAGE 2 DOSAGE AND ADMINISTRATION For those patients who fail to respond to the 0.4 mg dose after 2 to 4 weeks of dosing, the dose of Flomax capsules can be increased to 0.8 mg once daily. Flomax 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 Flomax 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. 3 DOSAGE FORMS AND STRENGTHS 4 CONTRAINDICATIONS Flomax capsules are contraindicated in patients known to be hypersensitive to tamsulosin hydrochloride or any component of Flomax capsules. Reactions have included skin rash, urticaria, pruritus, angioedema, and respiratory symptoms [see Adverse Reactions (6.2)]. 5 WARNINGS AND PRECAUTIONS Orthostasis The signs and symptoms of orthostasis (postural hypotension, dizziness, and vertigo) were detected more frequently in Flomax capsule-treated patients than in placebo recipients. As with other alpha adrenergic blocking agents there is a potential risk of syncope [see Adverse Reactions (6.1)]. Patients beginning treatment with Flomax capsules should be cautioned to avoid situations in which injury could result should syncope occur [see Patient Counseling Information (17.1)]. Drug Interactions Tamsulosin is extensively metabolized, mainly by CYP3A4 and CYP2D6. Flomax capsules 0.4 mg should not be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole) [see Drug Interactions (7.1) and Clinical Pharmacology (12.3)]. Flomax 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, in patients known to be CYP2D6 poor metabolizers particularly at a dose higher than 0.4 mg (e.g., 0.8 mg) [see Drug Interactions (7.1) and Clinical Pharmacology (12.3)]. Flomax capsules should be used with caution in combination with cimetidine, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg) [see Drug Interactions (7.1) and Clinical Pharmacology (12.3)]. Flomax capsules should not be used in combination with other alpha adrenergic blocking agents [see Drug Interactions (7.2) and Clinical Pharmacology (12.3)]. Caution is advised when alpha adrenergic blocking agents including Flomax 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 (7.3) and Clinical Pharmacology (12.3)]. Caution should be exercised with concomitant administration of warfarin and Flomax capsules [see Drug Interactions (7.4) and Clinical Pharmacology (12.3)]. Priapism Rarely (probably less than 1 in 50,000 patients), tamsulosin, like other alpha1 antagonists, has been associated with priapism (persistent painful penile erection unrelated to sexual activity). Because this condition can lead to permanent impotence if not properly treated, patients must be advised about the seriousness of the condition [see Patient Counseling Information (17.2)]. Screening for Prostate Cancer Prostate cancer and BPH frequently co-exist; therefore, patients should be screened for the presence of prostate cancer prior to treatment with Flomax capsules and at regular intervals afterwards [see Patient Counseling Information (17.3)]. Intraoperative Floppy Iris Syndrome Intraoperative Floppy Iris Syndrome (IFIS) has been observed during cataract surgery in some patients on or previously treated with alpha1 blockers, including Flomax capsules [see Adverse Reactions (6.2)]. Most reports were in patients taking the alpha1 blocker when IFIS occurred, but in some cases, the alpha1 blocker had been stopped prior to surgery. In most of these cases, the alpha1 blocker had been stopped recently prior to surgery (2 to 14 days), but in a few cases, IFIS was reported after the patient had been off the alpha1 blocker for a longer period (5 weeks to 9 months). IFIS is a variant of small pupil syndrome and is characterized by the combination of a flaccid iris that billows in response to intraoperative irrigation currents, progressive intraoperative miosis despite preoperative dilation with standard mydriatic drugs and potential prolapse of the iris toward the phacoemulsification incisions. The patient's ophthalmologist should be prepared for possible modifications to their surgical technique, such as the utilization of iris hooks, iris dilator rings, or viscoelastic substances. IFIS may increase the risk of eye complications during and after the operation. The benefit of stopping alpha1 blocker therapy prior to cataract surgery has not been established. The initiation of therapy with tamsulosin in patients for whom cataract surgery is scheduled is not recommended. Sulfa Allergy In patients with sulfa allergy, allergic reaction to Flomax capsules has been rarely reported. If a patient reports a serious or life-threatening sulfa allergy, caution is warranted when administering Flomax capsules. 6ADVERSE REACTIONS 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 Flomax capsules were used. These studies evaluated safety in 1783 patients treated with Flomax capsules and 798 patients administered placebo. Table 1 summarizes the treatment-emergent adverse events that occurred in ≥2% of patients receiving either Flomax 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.
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 orthostatic test result at 4 hours post-dose was observed in 7% of patients (37 of 498) who received Flomax capsules 0.4 mg once daily and in 3% of the patients (8 of 253) who received placebo. At 8 hours post-dose, a positive orthostatic test result was observed for 6% of the patients (31 of 498) who received Flomax capsules 0.4 mg once daily and 4% (9 of 250) who received placebo (Note: patients in the 0.8 mg group received 0.4 mg once daily for the first week of Study 1). In Studies 1 and 2, at least one positive orthostatic test result was observed during the course of these studies for 81 of the 502 patients (16%) in the Flomax capsules 0.4 mg once-daily group, 92 of the 491 patients (19%) in the Flomax capsules 0.8 mg once-daily group, and 54 of the 493 patients (11%) in the placebo group. Because orthostasis was detected more frequently in Flomax capsule-treated patients than in placebo recipients, there is a potential risk of syncope [see Warnings and Precautions (5.1)]. Abnormal Ejaculation Abnormal ejaculation includes ejaculation failure, ejaculation disorder, retrograde ejaculation, and ejaculation decrease. As shown in Table 1, abnormal ejaculation was associated with Flomax capsules administration and was dose-related in the U.S. studies. Withdrawal from these clinical studies of Flomax capsules because of abnormal ejaculation was also dose-dependent, with 8 of 492 patients (1.6%) in the 0.8 mg group and no patients in the 0.4 mg or placebo groups discontinuing treatment due to abnormal ejaculation. Laboratory Tests No laboratory test interactions with Flomax capsules are known. Treatment with Flomax capsules for up to 12 months had no significant effect on prostate-specific antigen (PSA). Postmarketing Experience The following adverse reactions have been identified during post-approval use of Flomax capsules. 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. Decisions to include these reactions in labeling are typically based on one or more of the following factors: (1) seriousness of the reaction, (2) frequency of reporting, or (3) strength of causal connection to Flomax capsules. Allergic-type reactions such as skin rash, urticaria, pruritus, angioedema, and respiratory symptoms have been reported with positive rechallenge in some cases. Priapism has been reported rarely. Infrequent reports of dyspnea, palpitations, hypotension, atrial fibrillation, arrhythmia, tachycardia, skin desquamation including reports of Stevens-Johnson syndrome, constipation, and vomiting have been received during the postmarketing period. During cataract surgery, a variant of small pupil syndrome known as Intraoperative Floppy Iris Syndrome (IFIS) has been reported in association with alpha1 blocker therapy [see Warnings and Precautions (5.5)]. 7 DRUG INTERACTIONS 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 Cmax 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 Flomax 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 Cmax 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 Flomax 0.4 mg is co-administered with strong CYP3A4 inhibitors in CYP2D6 PMs, Flomax 0.4 mg capsules 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 Flomax have not been evaluated [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. The effects of co-administration of both a CYP3A4 and a CYP2D6 inhibitor with Flomax capsules have not been evaluated. However, there is a potential for significant increase in tamsulosin exposure when Flomax 0.4 mg is co-administered 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)]. Other Alpha Adrenergic Blocking Agents The pharmacokinetic and pharmacodynamic interactions between Flomax capsules and other alpha adrenergic blocking agents have not been determined; however, interactions between Flomax capsules and other alpha adrenergic blocking agents may be expected [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. PDE5 Inhibitors Caution is advised when alpha adrenergic blocking agents including Flomax 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 Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. 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 Flomax capsules [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)]. Nifedipine, Atenolol, Enalapril Dosage adjustments are not necessary when Flomax capsules are administered concomitantly with nifedipine, atenolol, or enalapril [see Clinical Pharmacology (12.3)]. Digoxin and Theophylline Dosage adjustments are not necessary when a Flomax capsule is administered concomitantly with digoxin or theophylline [see Clinical Pharmacology (12.3)]. Furosemide Flomax capsules had no effect on the pharmacodynamics (excretion of electrolytes) of furosemide. While furosemide produced an 11% to 12% reduction in tamsulosin hydrochloride Cmax and AUC, these changes are expected to be clinically insignificant and do not require adjustment of the Flomax capsules dosage [see Clinical Pharmacology (12.3)]. 8 USE IN SPECIFIC POPULATIONS Pregnancy Teratogenic Effects, Pregnancy Category B. Administration of tamsulosin hydrochloride to pregnant female rats at dose levels up to approximately 50 times the human therapeutic AUC exposure (300 mg/kg/day) revealed no evidence of harm to the fetus. Administration of tamsulosin hydrochloride to pregnant rabbits at dose levels up to 50 mg/kg/day produced no evidence of fetal harm. Flomax capsules are not indicated for use in women. Nursing Mothers Flomax capsules are not indicated for use in women. Pediatric Use Flomax capsules are not indicated for use in pediatric populations. Efficacy and positive benefit/risk of tamsulosin hydrochloride was not demonstrated in two studies conducted in patients 2 years to 16 years of age with elevated detrusor leak point pressure (>40 cm H2O) associated with known neurological disorder (e.g., spina bifida). Patients in both studies were treated on a weight-based mg/kg schema (0.025 mg, 0.05 mg, 0.1 mg, 0.2 mg, or 0.4 mg tamsulosin hydrochloride) for the reduction in detrusor leak point pressure below 40 cm H2O. In a randomized, double-blind, placebo-controlled, 14-week, pharmacokinetic, safety and efficacy study in 161 patients, no statistically significant difference in the proportion of responders was observed between groups receiving tamsulosin hydrochloride and placebo. In an open-label, 12-month safety study, 87 patients were treated with tamsulosin hydrochloride. The most frequently reported adverse events (≥5%) from the pooled data of both studies were urinary tract infection, vomiting, pyrexia, headache, nasopharyngitis, cough, pharyngitis, influenza, diarrhea, abdominal pain, and constipation. Geriatric Use Of the total number of subjects (1783) in clinical studies of tamsulosin, 36% were 65 years of age and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and the other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out [see Clinical Pharmacology (12.3)]. Renal Impairment Patients with renal impairment do not require an adjustment in Flomax capsules dosing. However, patients with end-stage renal disease (CLcr <10 mL/min/1.73 m2) have not been studied [see Clinical Pharmacology (12.3)]. Hepatic Impairment Patients with moderate hepatic impairment do not require an adjustment in Flomax capsules dosage. Flomax has not been studied in patients with severe hepatic impairment [see Clinical Pharmacology (12.3)]. 10 OVERDOSAGE Should overdosage of Flomax capsules lead to hypotension [see Warnings and Precautions (5.1) and Adverse Reactions (6.1)], support of the cardiovascular system is of first importance. Restoration of blood pressure and normalization of heart rate may be accomplished by keeping the patient in the supine position. If this measure is inadequate, then administration of intravenous fluids should be considered. If necessary, vasopressors should then be used and renal function should be monitored and supported as needed. Laboratory data indicate that tamsulosin hydrochloride is 94% to 99% protein bound; therefore, dialysis is unlikely to be of benefit. 11 DESCRIPTION Tamsulosin hydrochloride is an antagonist of alpha1A adrenoceptors in the prostate. Tamsulosin hydrochloride is (-)-(R)-5-[2-[[2-(o-Ethoxyphenoxy) ethyl]amino]propyl]-2-methoxybenzenesulfonamide, monohydrochloride. Tamsulosin hydrochloride is a white crystalline powder that melts with decomposition at approximately 230°C. It is sparingly soluble in water and methanol, slightly soluble in glacial acetic acid and ethanol, and practically insoluble in ether. The empirical formula of tamsulosin hydrochloride is C20H28N2O5S • HCl. The molecular weight of tamsulosin hydrochloride is 444.98. Its structural formula is: Each Flomax capsule for oral administration contains tamsulosin hydrochloride 0.4 mg, and the following inactive ingredients: methacrylic acid copolymer dispersion, NF; microcrystalline cellulose, NF; triacetin, USP; calcium stearate, NF; talc, USP; FD&C blue No. 2; titanium dioxide; ferric oxide; gelatin, and trace amounts of black edible ink. 12 CLINICAL PHARMACOLOGY 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 alpha1 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 alpha1 adrenoceptor blocking agent, exhibits selectivity for alpha1 receptors in the human prostate. At least three discrete alpha1 adrenoceptor subtypes have been identified: alpha1A, alpha1B, and alpha1D; their distribution differs between human organs and tissue. Approximately 70% of the alpha1 receptors in the human prostate are of the alpha1A subtype. Flomax capsules are not intended for use as an antihypertensive drug. Pharmacodynamics Urologic pharmacodynamic effects have been evaluated in neurologically impaired pediatric patients and in adults with BPH [see Use in Specific Populations (8.4) and Clinical Studies (14)]. Pharmacokinetics The pharmacokinetics of tamsulosin hydrochloride have been evaluated in adult healthy volunteers and patients with BPH after single and/or multiple administration with doses ranging from 0.1 mg to 1 mg. Absorption Absorption of tamsulosin hydrochloride from Flomax capsules 0.4 mg is essentially complete (>90%) following oral administration under fasting conditions. Tamsulosin hydrochloride exhibits linear kinetics following single and multiple dosing, with achievement of steady-state concentrations by the fifth day of once-a-day dosing. Effect of Food The time to maximum concentration (Tmax) is reached by 4 to 5 hours under fasting conditions and by 6 to 7 hours when Flomax capsules are administered with food. Taking Flomax capsules under fasted conditions results in a 30% increase in bioavailability (AUC) and 40% to 70% increase in peak concentrations (Cmax) compared to fed conditions (Figure 1). Figure 1 Mean Plasma Tamsulosin Hydrochloride Concentrations Following Single-Dose Administration of Flomax Capsules 0.4 mg Under Fasted and Fed Conditions (n=8) The effects of food on the pharmacokinetics of tamsulosin hydrochloride are consistent regardless of whether a Flomax capsule is taken with a light breakfast or a high-fat breakfast (Table 2).
The mean steady-state apparent volume of distribution of tamsulosin hydrochloride after intravenous administration to 10 healthy male adults was 16 L, which is suggestive of distribution into extracellular fluids in the body. Tamsulosin hydrochloride is extensively bound to human plasma proteins (94% to 99%), primarily alpha1 acid glycoprotein (AAG), with linear binding over a wide concentration range (20 to 600 ng/mL). The results of two-way in vitro studies indicate that the binding of tamsulosin hydrochloride to human plasma proteins is not affected by amitriptyline, diclofenac, glyburide, simvastatin plus simvastatin-hydroxy acid metabolite, warfarin, diazepam, propranolol, trichlormethiazide, or chlormadinone. Likewise, tamsulosin hydrochloride had no effect on the extent of binding of these drugs. MetabolismThere is no enantiomeric bioconversion from tamsulosin hydrochloride [R(-) isomer] to the S(+) isomer in humans. Tamsulosin hydrochloride is extensively metabolized by cytochrome P450 enzymes in the liver and less than 10% of the dose is excreted in urine unchanged. However, the pharmacokinetic profile of the metabolites in humans has not been established. Tamsulosin is extensively metabolized, mainly by CYP3A4 and CYP2D6 as well as via some minor participation of other CYP isoenzymes. Inhibition of hepatic drug-metabolizing enzymes may lead to increased exposure to tamsulosin [see Warnings and Precautions (5.2) and Drug Interactions (7.1)]. The metabolites of tamsulosin hydrochloride undergo extensive conjugation to glucuronide or sulfate prior to renal excretion. Incubations with human liver microsomes showed no evidence of clinically significant metabolic interactions between tamsulosin hydrochloride and amitriptyline, albuterol (beta agonist), glyburide (glibenclamide) and finasteride (5alpha-reductase inhibitor for treatment of BPH). However, results of the in vitro testing of the tamsulosin hydrochloride interaction with diclofenac and warfarin were equivocal. ExcretionOn administration of the radiolabeled dose of tamsulosin hydrochloride to 4 healthy volunteers, 97% of the administered radioactivity was recovered, with urine (76%) representing the primary route of excretion compared to feces (21%) over 168 hours. Following intravenous or oral administration of an immediate-release formulation, the elimination half-life of tamsulosin hydrochloride in plasma ranged from 5 to 7 hours. Because of absorption rate-controlled pharmacokinetics with Flomax capsules, the apparent half-life of tamsulosin hydrochloride is approximately 9 to 13 hours in healthy volunteers and 14 to 15 hours in the target population. Tamsulosin hydrochloride undergoes restrictive clearance in humans, with a relatively low systemic clearance (2.88 L/h). Specific Populations Pediatric Use Flomax capsules are not indicated for use in pediatric populations [see Use in Specific Populations (8.4)]. Geriatric (Age) Use Cross-study comparison of Flomax capsules overall exposure (AUC) and half-life indicates that the pharmacokinetic disposition of tamsulosin hydrochloride may be slightly prolonged in geriatric males compared to young, healthy male volunteers. Intrinsic clearance is independent of tamsulosin hydrochloride binding to AAG, but diminishes with age, resulting in a 40% overall higher exposure (AUC) in subjects of age 55 to 75 years compared to subjects of age 20 to 32 years [see Use in Specific Populations (8.5)]. Renal Impairment The pharmacokinetics of tamsulosin hydrochloride have been compared in 6 subjects with mild-moderate (30≤ CLcr <70 mL/min/1.73 m2) or moderate-severe (10≤ CLcr <30 mL/min/1.73 m2) renal impairment and 6 normal subjects (CLcr >90 mL/min/1.73 m2). While a change in the overall plasma concentration of tamsulosin hydrochloride was observed as the result of altered binding to AAG, the unbound (active) concentration of tamsulosin hydrochloride, as well as the intrinsic clearance, remained relatively constant. Therefore, patients with renal impairment do not require an adjustment in Flomax capsules dosing. However, patients with end-stage renal disease (CLcr <10 mL/min/1.73 m2) have not been studied [see Use in Specific Populations (8.6)]. Hepatic Impairment The pharmacokinetics of tamsulosin hydrochloride have been compared in 8 subjects with moderate hepatic impairment (Child-Pugh’s classification: Grades A and B) and 8 normal subjects. While a change in the overall plasma concentration of tamsulosin hydrochloride was observed as the result of altered binding to AAG, the unbound (active) concentration of tamsulosin hydrochloride does not change significantly, with only a modest (32%) change in intrinsic clearance of unbound tamsulosin hydrochloride. Therefore, patients with moderate hepatic impairment do not require an adjustment in Flomax capsules dosage. Flomax has not been studied in patients with severe hepatic impairment [see Use in Specific Populations (8.7)]. Drug Interactions Cytochrome P450 Inhibition Strong and Moderate Inhibitors of CYP3A4 or CYP2D6 The effects of paroxetine (a strong inhibitor of CYP2D6) at 20 mg once daily for 9 days on the pharmacokinetics of a single Flomax capsule 0.4 mg dose was investigated in 24 healthy volunteers (age range 23 to 47 years). Concomitant treatment with paroxetine resulted in an increase in the Cmax and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively [see Warnings and Precautions (5.2) and Drug Interactions (7.1)]. A similar increase in exposure is expected in CYP2D6 poor metabolizers (PM) as compared to extensive metabolizers (EM). A fraction of the population (about 7% of Caucasians and 2% of African Americans) are CYP2D6 PMs. Since CYP2D6 PMs cannot be readily identified and the potential for significant increase in tamsulosin exposure exists when Flomax 0.4 mg is co-administered with strong CYP3A4 inhibitors in CYP2D6 PMs, Flomax 0.4 mg capsules should not be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole) [see Warnings and Precautions (5.2) and Drug Interactions (7.1)]. The effects of concomitant administration of a moderate CYP2D6 inhibitor (e.g., terbinafine) on the pharmacokinetics of Flomax have not been evaluated [see Warnings and Precautions (5.2) and Drug Interactions (7.1)]. The effects of co-administration of both a CYP3A4 and a CYP2D6 inhibitor with Flomax capsules have not been evaluated. However, there is a potential for significant increase in tamsulosin exposure when Flomax 0.4 mg is co-administered with a combination of both CYP3A4 and CYP2D6 inhibitors [see Warnings and Precautions (5.2) and Drug Interactions (7.1)]. Cimetidine The effects of cimetidine at the highest recommended dose (400 mg every 6 hours for 6 days) on the pharmacokinetics of a single Flomax capsule 0.4 mg dose was investigated in 10 healthy volunteers (age range 21 to 38 years). 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 Drug Interactions (7.1)]. Other Alpha Adrenergic Blocking Agents The pharmacokinetic and pharmacodynamic interactions between Flomax capsules and other alpha adrenergic blocking agents have not been determined; however, interactions between Flomax capsules and other alpha adrenergic blocking agents may be expected [see Warnings and Precautions (5.2) and Drug Interactions (7.2)]. PDE5 Inhibitors Caution is advised when alpha adrenergic blocking agents, including Flomax, 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 Warnings and Precautions (5.2) and Drug Interactions (7.3)]. 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. Therefore, caution should be exercised with concomitant administration of warfarin and Flomax capsules [see Warnings and Precautions (5.2) and Drug Interactions (7.4)]. Nifedipine, Atenolol, Enalapril In three studies in hypertensive subjects (age range 47 to 79 years) whose blood pressure was controlled with stable doses of nifedipine, atenolol, or enalapril for at least 3 months, Flomax capsules 0.4 mg for 7 days followed by Flomax capsules 0.8 mg for another 7 days (n=8 per study) resulted in no clinically significant effects on blood pressure and pulse rate compared to placebo (n=4 per study). Therefore, dosage adjustments are not necessary when Flomax capsules are administered concomitantly with nifedipine, atenolol, or enalapril [see Drug Interactions (7.5)]. Digoxin and Theophylline In two studies in healthy volunteers (n=10 per study; age range 19 to 39 years) receiving Flomax capsules 0.4 mg/day for 2 days, followed by Flomax capsules 0.8 mg/day for 5 to 8 days, single intravenous doses of digoxin 0.5 mg or theophylline 5 mg/kg resulted in no change in the pharmacokinetics of digoxin or theophylline. Therefore, dosage adjustments are not necessary when a Flomax capsule is administered concomitantly with digoxin or theophylline [see Drug Interactions (7.6)]. Furosemide The pharmacokinetic and pharmacodynamic interaction between Flomax capsules 0.8 mg/day (steady-state) and furosemide 20 mg intravenously (single dose) was evaluated in 10 healthy volunteers (age range 21 to 40 years). Flomax capsules had no effect on the pharmacodynamics (excretion of electrolytes) of furosemide. While furosemide produced an 11% to 12% reduction in tamsulosin hydrochloride Cmax and AUC, these changes are expected to be clinically insignificant and do not require adjustment of the Flomax capsules dosage [see Drug Interactions (7.7)]. 13 NONCLINICAL TOXICOLOGY Carcinogenesis, Mutagenesis, Impairment of Fertility Rats administered doses up to 43 mg/kg/day in males and 52 mg/kg/day in females had no increases in tumor incidence, with the exception of a modest increase in the frequency of mammary gland fibroadenomas in female rats receiving doses ≥5.4 mg/kg (P<0.015). The highest doses of tamsulosin hydrochloride evaluated in the rat carcinogenicity study produced systemic exposures (AUC) in rats 3 times the exposures in men receiving the maximum therapeutic dose of 0.8 mg/day. Mice were administered doses up to 127 mg/kg/day in males and 158 mg/kg/day in females. There were no significant tumor findings in male mice. Female mice treated for 2 years with the two highest doses of 45 and 158 mg/kg/day had statistically significant increases in the incidence of mammary gland fibroadenomas (P<0.0001) and adenocarcinomas (P<0.0075). The highest dose levels of tamsulosin hydrochloride evaluated in the mice carcinogenicity study produced systemic exposures (AUC) in mice 8 times the exposures in men receiving the maximum therapeutic dose of 0.8 mg/day. The increased incidences of mammary gland neoplasms in female rats and mice were considered secondary to tamsulosin hydrochloride-induced hyperprolactinemia. It is not known if Flomax capsules elevate prolactin in humans. The relevance for human risk of the findings of prolactin-mediated endocrine tumors in rodents is not known. Tamsulosin hydrochloride produced no evidence of mutagenic potential in vitro in the Ames reverse mutation test, mouse lymphoma thymidine kinase assay, unscheduled DNA repair synthesis assay, and chromosomal aberration assays in Chinese hamster ovary cells or human lymphocytes. There were no mutagenic effects in the in vivo sister chromatid exchange and mouse micronucleus assay. Studies in rats revealed significantly reduced fertility in males dosed with single or multiple daily doses of 300 mg/kg/day of tamsulosin hydrochloride (AUC exposure in rats about 50 times the human exposure with the maximum therapeutic dose). The mechanism of decreased fertility in male rats is considered to be an effect of the compound on the vaginal plug formation possibly due to changes of semen content or impairment of ejaculation. The effects on fertility were reversible, showing improvement by 3 days after a single dose and 4 weeks after multiple dosing. Effects on fertility in males were completely reversed within nine weeks of discontinuation of multiple dosing. Multiple doses of 10 and 100 mg/kg/day tamsulosin hydrochloride (1/5 and 16 times the anticipated human AUC exposure) did not significantly alter fertility in male rats. Effects of tamsulosin hydrochloride on sperm counts or sperm function have not been evaluated. Studies in female rats revealed significant reductions in fertility after single or multiple dosing with 300 mg/kg/day of the R-isomer or racemic mixture of tamsulosin hydrochloride, respectively. In female rats, the reductions in fertility after single doses were considered to be associated with impairments in fertilization. Multiple dosing with 10 or 100 mg/kg/day of the racemic mixture did not significantly alter fertility in female rats. 14 CLINICAL STUDIES Four placebo-controlled clinical studies and one active-controlled clinical study enrolled a total of 2296 patients (1003 received Flomax capsules 0.4 mg once daily, 491 received Flomax capsules 0.8 mg once daily, and 802 were control patients) in the U.S. and Europe. In the two U.S. placebo-controlled, double-blind, 13-week, multicenter studies [Study 1 (US92-03A) and Study 2 (US93-01)], 1486 men with the signs and symptoms of BPH were enrolled. In both studies, patients were randomized to either placebo, Flomax capsules 0.4 mg once daily, or Flomax capsules 0.8 mg once daily. Patients in Flomax capsules 0.8 mg once-daily treatment groups received a dose of 0.4 mg once daily for one week before increasing to the 0.8 mg once-daily dose. The primary efficacy assessments included: 1) total American Urological Association (AUA) Symptom Score questionnaire, which evaluated irritative (frequency, urgency, and nocturia), and obstructive (hesitancy, incomplete emptying, intermittency, and weak stream) symptoms, where a decrease in score is consistent with improvement in symptoms; and 2) peak urine flow rate, where an increased peak urine flow rate value over baseline is consistent with decreased urinary obstruction. Mean changes from baseline to Week 13 in total AUA Symptom Score were significantly greater for groups treated with Flomax capsules 0.4 mg and 0.8 mg once daily compared to placebo in both U.S. studies (Table 3, Figures 2A and 2B). The changes from baseline to Week 13 in peak urine flow rate were also significantly greater for the Flomax capsules 0.4 mg and 0.8 mg once-daily groups compared to placebo in Study 1, and for the Flomax capsules 0.8 mg once-daily group in Study 2 (Table 3, Figures 3A and 3B). Overall there were no significant differences in improvement observed in total AUA Symptom Scores or peak urine flow rates between the 0.4 mg and the 0.8 mg dose groups with the exception that the 0.8 mg dose in Study 1 had a significantly greater improvement in total AUA Symptom Score compared to the 0.4 mg dose.
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