Tamsulosin Hydrochloride .4 mg Capsule, 60-count — NDC 68788-4145-6 (Billing 68788-4145-06)

12 CLINICAL PHARMACOLOGY

12.1Mechanism 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.

12.2Pharmacodynamics Urologic pharmacodynamic effects have been evaluated in neurologically impaired pediatric patients and in adults with BPH [see Use In Specific Populations ( ) and Clinical Studies ( )].

12.3Pharmacokinetics 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 tamsulosin hydrochloride 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 (T max ) is reached by 4 to 5 hours under fasting conditions and by 6 to 7 hours when tamsulosin hydrochloride capsules are administered with food. Taking tamsulosin hydrochloride capsules under fasted conditions results in a 30% increase in bioavailability (AUC) and 40% to 70% increase in peak concentrations (C max ) compared to fed conditions (Figure 1). Figure 1 Mean Plasma Tamsulosin Hydrochloride Concentrations Following Single-Dose Administration of Tamsulosin Hydrochloride 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 tamsulosin hydrochloride capsule is taken with a light breakfast or a high-fat breakfast (Table 2).

Table 1Mean (± S.D.) Pharmacokinetic Parameters Following Tamsulosin Hydrochloride Capsules 0.4 mg Once Daily or 0.8 mg Once Daily with a Light Breakfast, High-Fat Breakfast or Fasted Pharmacokinetic Parameter 0.4 mg QD to healthy volunteers; n=23 (age range 18 to 32 years) 0.8 mg QD to healthy volunteers; n=22 (age range 55 to 75 years) C min = observed minimum concentration C max = observed maximum tamsulosin hydrochloride plasma concentration T max = median time-to-maximum concentration T 1/2 = observed half-life AUC τ = area under the tamsulosin hydrochloride plasma time curve over the dosing interval Light Fasted Light High-Fat Fasted Breakfast Breakfast Breakfast C min (ng/mL) 4.0 ± 2.6 3.8 ± 2.5 12.3 ± 6.7 13.5 ± 7.6 13.3 ±

13.3C max (ng/mL) 10.1 ± 4.8 17.1 ± 17.1 29.8 ± 10.3 29.1 ± 11.0 41.6 ±

15.6C max /C min Ratio 3.1 ± 1.0 5.3 ± 2.2 2.7 ± 0.7 2.5 ± 0.8 3.6 ±

1.1T max (hours) 6.0… [Excerpted — this section continues on DailyMed.]

12.1Mechanism 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.

12.3Pharmacokinetics 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 tamsulosin hydrochloride 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 (T max ) is reached by 4 to 5 hours under fasting conditions and by 6 to 7 hours when tamsulosin hydrochloride capsules are administered with food. Taking tamsulosin hydrochloride capsules under fasted conditions results in a 30% increase in bioavailability (AUC) and 40% to 70% increase in peak concentrations (C max ) compared to fed conditions (Figure 1). Figure 1 Mean Plasma Tamsulosin Hydrochloride Concentrations Following Single-Dose Administration of Tamsulosin Hydrochloride 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 tamsulosin hydrochloride capsule is taken with a light breakfast or a high-fat breakfast (Table 2).

Table 1Mean (± S.D.) Pharmacokinetic Parameters Following Tamsulosin Hydrochloride Capsules 0.4 mg Once Daily or 0.8 mg Once Daily with a Light Breakfast, High-Fat Breakfast or Fasted Pharmacokinetic Parameter 0.4 mg QD to healthy volunteers; n=23 (age range 18 to 32 years) 0.8 mg QD to healthy volunteers; n=22 (age range 55 to 75 years) C min = observed minimum concentration C max = observed maximum tamsulosin hydrochloride plasma concentration T max = median time-to-maximum concentration T 1/2 = observed half-life AUC τ = area under the tamsulosin hydrochloride plasma time curve over the dosing interval Light Fasted Light High-Fat Fasted Breakfast Breakfast Breakfast C min (ng/mL) 4.0 ± 2.6 3.8 ± 2.5 12.3 ± 6.7 13.5 ± 7.6 13.3 ±

13.3C max (ng/mL) 10.1 ± 4.8 17.1 ± 17.1 29.8 ± 10.3 29.1 ± 11.0 41.6 ±

15.6C max /C min Ratio 3.1 ± 1.0 5.3 ± 2.2 2.7 ± 0.7 2.5 ± 0.8 3.6 ±

1.1T max (hours) 6.0 4.0 7.0 6.6

5.0T 1/2 (hours) - - - - 14.9 ±

3.9AUC τ (ng•hr/mL) 151 ± 81.5 199 ± 94.1 440 ± 195 449 ± 217 557 ± 257 Distribution 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 alpha 1 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. Metabolism There 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 sulf… [Excerpted — this section continues on DailyMed.]

12.2Pharmacodynamics Urologic pharmacodynamic effects have been evaluated in neurologically impaired pediatric patients and in adults with BPH [see Use In Specific Populations ( ) and Clinical Studies ( )].

14 CLINICAL STUDIES Four placebo-controlled clinical studies and one active-controlled clinical study enrolled a total of 2296 patients (1003 received tamsulosin hydrochloride capsules, 0.4 mg once daily, 491 received tamsulosin hydrochloride 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, tamsulosin hydrochloride capsules 0.4 mg once daily, or tamsulosin hydrochloride capsules 0.8 mg once daily.

Patients in tamsulosin hydrochloride 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 tamsulosin hydrochloride 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 tamsulosin hydrochloride capsules, 0.4 mg and 0.8 mg once-daily groups compared to placebo in Study 1, and for the tamsulosin hydrochloride 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. Table 2Mean (±S.D.) Changes from Baseline to Week 13 in Total AUA Symptom Score ** and Peak Urine Flow Rate (mL/sec) Total AUA Symptom Score Peak Urine Flow Rate * Statistically significant difference from placebo (p-value ≤ 0.050; Bonferroni-Holm multiple testprocedure). ** Total AUA Symptom Scores ranged from 0 to 35. † Peak urine flow rate measured 4 to 8 hours post dose at Week 13. ‡ Peak urine flow rate measured 24 to 27 hours post dose at Week 13.

Week 13: For patients not completing the 13-week study, the last observation was carried forward. Mean Baseline Value Mean Change Mean Baseline Value Mean Change Study 1 † Tamsulosin Hydrochloride Capsules 19.9 ± 4.9 -9.6* ± 6.7 9.57 ± 2.51 1.78* ± 3.35 0.8 mg once daily n=247 n=237 n=247 n=247 Tamsulosin Hydrochloride Capsules 19.8 ± 5.0 -8.3* ± 6.5 9.46 ± 2.49 1.75* ± 3.57 0.4 mg once daily n=254 n=246 n=254 n=254 Placebo 19.6 ± 4.9 -5.5 ± 6.6 9.75 ± 2.54 0.52 ± 3.39 n=254 n=246 n=254 n=253 Study 2 ‡ Tamsulosin Hydrochloride Capsules 18.2 ± 5.6 -5.8* ± 6.4 9.96 ± 3.16 1.79* ± 3.36 0.8 mg once daily n=244 n=238 n=244 n=237 Tamsulosin Hydrochloride Capsules 17.9 ± 5.8 -5.1* ± 6.4 9.94 ± 3.14 1.52 ± 3.64 0.4 mg once daily n=248 n=244 n=248 n=244 Placebo 19.2 ± 6.0 -3.6 ± 5.7 9.95 ± 3.12 0.93 ± 3.28 n=239 n=235 n=239 n=235 Mean total AUA Symptom Scores for both tamsulosin hydrochloride capsules, 0.4 mg and 0.8 mg once-daily groups showed a rapid decrease starting at 1 week after dosing and remained decreased through 13 weeks in both studies (Figures 2A and 2B).

In Study 1, 400 patients (53% of the originally randomized group) elected to continue in their originally assigned treatment groups in a double-blind, placebo-controlled, 40-week extension trial (138 patients on 0.4 mg, 135 patients on 0.8 mg… [Excerpted — this section continues on DailyMed.]

13 NONCLINICAL TOXICOLOGY

13.1Carcinogenesis, 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 tamsulosin hydrochloride 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.