Tamsulosin Hydrochloride: Package Insert and Label Information (Page 2 of 5)

6.2 Postmarketing Experience

The following adverse reactions have been identified during post-approval use of tamsulosin hydrochloride 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 tamsulosin hydrochloride 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, erythema multiforme, dermatitis exfoliative, constipation, vomiting, dry mouth, visual impairment, and epistaxis have been received during the postmarketing period. During cataract and glaucoma surgery, a variant of small pupil syndrome known as Intraoperative Floppy Iris Syndrome (IFIS) has been reported in association with alpha 1 blocker therapy [see Warnings and Precautions (5.5)] .

7 DRUG INTERACTIONS

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 0.4 mg is co-administered 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 co-administration 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 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)] .

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 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)] .

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 capsule is 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)] .

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

Risk Summary

Tamsulosin hydrochloride is not indicated for use in women. There are no adequate data on the developmental risk associated with the use of tamsulosin hydrochloride in pregnant women. No adverse developmental effects were observed in animal studies in which tamsulosin hydrochloride was administered to rats or rabbits during the period of organogenesis (GD 7 to 17 in the rat and GD 6 to 18 in the rabbit) [ see Data ] .

In the U.S. general population, the estimated background risk of major birth defects and of miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Data

Administration of tamsulosin hydrochloride to pregnant female rats during the period of organogenesis 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 during the period of organogenesis at dose levels up to 50 mg/kg/day produced no evidence of fetal harm.

8.2 Lactation

Tamsulosin hydrochloride is not indicated for use in women. There are no data on the presence of tamsulosin hydrochloride in human milk, the effects of tamsulosin hydrochloride on the breastfed infant, or the effects of tamsulosin hydrochloride on milk production. Tamsulosin hydrochloride is present in the milk of lactating rats [ see Data ] .

Data

Oral administration of radiolabeled tamsulosin hydrochloride to rats demonstrated that tamsulosin hydrochloride and/or its metabolites are excreted into the milk of rats.

8.3 Females and Males of Reproductive Potential

Infertility

Males

Abnormal ejaculation including ejaculation failure, ejaculation disorder, retrograde ejaculation, and ejaculation decrease has been associated with tamsulosin hydrochloride [ see Clinical Trials Experience (6.1) ] . Studies in rats revealed significantly reduced fertility in males considered to be due to impairment of ejaculation, which was reversible [ see Nonclinical Toxicology (13.1) ] .

Females

Tamsulosin hydrochloride is not indicated for use in women. Female fertility in rats was significantly reduced, considered to be due to impairment of fertilization [ see Nonclinical Toxicology (13.1) ] .

8.4 Pediatric Use

Tamsulosin hydrochloride 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 H 2 O) 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 H 2 O. 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.

8.5 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)] .

8.6 Renal Impairment

Patients with renal impairment do not require an adjustment in tamsulosin hydrochloride capsules dosing. However, patients with end-stage renal disease (CL cr <10 mL/min/1.73 m 2) have not been studied [see Clinical Pharmacology (12.3)] .

8.7 Hepatic Impairment

Patients with moderate hepatic impairment do not require an adjustment in tamsulosin hydrochloride capsules dosage. Tamsulosin hydrochloride has not been studied in patients with severe hepatic impairment [see Clinical Pharmacology (12.3)] .

10 OVERDOSAGE

Should overdosage of tamsulosin hydrochloride 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 alpha 1A adrenoceptors in the prostate.
Tamsulosin hydrochloride is (-)-( R)-5-[2-[[2-( o -Ethoxyphenoxy) ethyl]amino]propyl]-2-methoxybenzenesulfonamide, monohydrochloride. Tamsulosin hydrochloride USP is a white or almost 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 molecular formula of tamsulosin hydrochloride is C 20 H 28 N 2 O 5 S • HCl. The molecular weight of tamsulosin hydrochloride is 444.98. Its structural formula is:

Chemical Structure
(click image for full-size original)

Each tamsulosin hydrochloride capsule, USP for oral administration contains tamsulosin hydrochloride USP 0.4 mg, and the following inactive ingredients: calcium stearate, FD&C Blue 2, gelatin, iron oxide red, iron oxide yellow, microcrystalline cellulose, methacrylic acid copolymer dispersion, sodium lauryl sulfate, talc, triacetin, and titanium dioxide. The capsules are printed with SW-9008 Black Ink containing black iron oxide, butyl alcohol, dehydrated alcohol, isopropyl alcohol, potassium hydroxide, propylene glycol, shellac, and strong ammonia solution. Meets USP dissolution test 10.

12 CLINICAL PHARMACOLOGY

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.

12.2 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)] .

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