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Pronunciation:

(tam SOO loe sin)

U.S. Brand Names:

Flomax®

Synonyms:

Tamsulosin Hydrochloride

Generic Available:

Canadian Brand Names:

Flomax®

Use:

Treatment of signs and symptoms of benign prostatic hyperplasia (BPH)

Pregnancy Risk Factor:

Pregnancy Implications:

Teratogenic effects were not observed in animal studies, however, tamsulosin is not indicated for use in women.

Lactation:

Not indicated for use in women

Contraindications:

Hypersensitivity to tamsulosin or any component of the formulation; concurrent use with phosphodiesterase-5 (PDE-5) inhibitors including sildenafil (>25 mg), tadalafil (if tamsulosin dose >0.4 mg/day), or vardenafil

Warnings/Precautions:

Not intended for use as an antihypertensive drug. May cause orthostasis, syncope or dizziness. Patients should avoid situations where injury may occur as a result of syncope. Rule out prostatic carcinoma before beginning therapy with tamsulosin.

Adverse Reactions:

>10%:

Cardiovascular: Studies specific for orthostatic hypotension: Overall, at least one positive test was observed in 16% of patients receiving 0.4 mg and 19% of patients receiving the 0.8 mg dose. "First-dose" orthostatic hypotension following a 0.4 mg dose was reported as 7% at 4 hours postdose and 6% at 8 hours postdose.

Central nervous system: Headache (19% to 21%), dizziness (15% to 17%)

Genitourinary: Abnormal ejaculation (8% to 18%)

Respiratory: Rhinitis (13% to 18%)

1% to 10%:

Cardiovascular: Chest pain (~4%)

Central nervous system: Somnolence (3% to 4%), insomnia (1% to 2%), vertigo (0.6% to 1%)

Endocrine & metabolic: Libido decreased (1% to 2%)

Gastrointestinal: Diarrhea (4% to 6%), nausea (3% to 4%), stomach discomfort (2% to 3%), bitter taste (2% to 3%)

Neuromuscular & skeletal: Weakness (8% to 9%), back pain (7% to 8%)

Ocular: Amblyopia (0.2% to 2%)

Respiratory: Pharyngitis (5% to 6%), cough (3% to 5%), sinusitis (2% to 4%)

Miscellaneous: Infection (9% to 11%), tooth disorder (1% to 2%)

<1% (Limited to important or life-threatening): Orthostasis (symptomatic) (0.2% to 0.4%), syncope (0.2% to 0.4%)

Postmarketing and/or case reports: Allergic reactions (rash, angioedema, pruritus, urticaria) priapism; constipation, palpitation, transaminases increased, vomiting

Overdosage/Toxicology:

Symptoms of overdose include headache and hypotension. Treatment is supportive.

Drug Interactions:

Substrate (major) of CYP2D6, 3A4

Alpha-adrenergic blockers: Risk of hypotension may increase in combination with other alpha-adrenergic blocking agents.

Beta-blockers: Beta-blockers may increase risk of first-dose orthostatic hypotension of tamsulosin

Calcium channel blockers: Risk of hypotension may increase

Cimetidine: Cimetidine may decrease tamsulosin clearance.

CYP2D6 inhibitors: May increase the levels/effects of tamsulosin. Example inhibitors include chlorpromazine, delavirdine, fluoxetine, miconazole, paroxetine, pergolide, quinidine, quinine, ritonavir, and ropinirole.

CYP3A4 inducers: CYP3A4 inducers may decrease the levels/effects of tamsulosin. Example inducers include aminoglutethimide, carbamazepine, nafcillin, nevirapine, phenobarbital, phenytoin, and rifamycins.

CYP3A4 inhibitors: May increase the levels/effects of tamsulosin. Example inhibitors include azole antifungals, ciprofloxacin, clarithromycin, diclofenac, doxycycline, erythromycin, imatinib, isoniazid, nefazodone, nicardipine, propofol, protease inhibitors, quinidine, and verapamil.

Sildenafil, tadalafil, vardenafil: Blood pressure-lowering effects are additive. Use of vardenafil is contraindicated by the manufacturer. Use sildenafil with extreme caution (dose 25 mg). Tadalafil may be used when tamsulosin dose is 0.4 mg/day.

Ethanol/Nutrition/Herb Interactions:

Food: Fasting increases bioavailability by 30% and peak concentration 40% to 70%.

Herb/Nutraceutical: Avoid saw palmetto (due to limited experience with this combination).

Mechanism of Action:

Tamsulosin is an antagonist of alpha1A adrenoreceptors in the prostate. Smooth muscle tone in the prostate is mediated by alpha1A adrenoreceptors; blocking them leads to relaxation of smooth muscle in the bladder neck and prostate causing an improvement of urine flow and decreased symptoms of BPH. Approximately 75% of the alpha1 receptors in the prostate are of the alpha1A subtype.

Pharmacodynamics/Kinetics:

Absorption: >90%

Protein binding: 94% to 99%, primarily to alpha1 acid glycoprotein (AAG)

Metabolism: Hepatic via CYP; metabolites undergo extensive conjugation to glucuronide or sulfate

Bioavailability: Fasting: 30% increase

Distribution: Vd: 16 L

Steady-state: By the fifth day of once-daily dosing

Half-life elimination: Healthy volunteers: 9-13 hours; Target population: 14-15 hours

Time to peak: Fasting: 4-5 hours; With food: 6-7 hours

Excretion: Urine (76%, <10% as unchanged drug); feces (21%)

Dosage:

Oral: Adults: 0.4 mg once daily ~30 minutes after the same meal each day; dose may be increased after 2-4 weeks to 0.8 mg once daily in patients who fail to respond. If therapy is interrupted for several days, restart with 0.4 mg once daily.

Dosage adjustment in renal impairment:

Clcr 10 mL/minute: No adjustment needed

Clcr<10 mL/minute: Not studied

Administration:

Capsules should be swallowed whole; do not crush, chew, or open.

Dietary Considerations:

Take once daily, 30 minutes after the same meal each day.

Patient Education:

Inform prescriber of all prescriptions, OTC medications, or herbal products you are taking, and any allergies you have. Do not take any new medication during therapy unless approved by prescriber. Take as directed; do not skip dose or discontinue without consulting prescriber. Avoid alcohol. Follow recommended diet and exercise program. May cause drowsiness, dizziness, or impaired judgment (use caution when driving or engaging in tasks that require alertness until response to drug is known); postural hypotension (use caution when rising from sitting or lying position or when climbing stairs); nausea (frequent mouth care or sucking lozenges may help); urinary incontinence (void before taking medication); ejaculatory disturbance (reversible, may resolve with continued use); diarrhea (buttermilk, boiled milk, or yogurt may help); palpitations or rapid heartbeat; respiratory difficulty, unusual cough, or sore throat; or other persistent side effects. Report palpitations or rapid heartbeat; respiratory difficulty; muscle weakness, fatigue, or pain; vision changes or hearing; rash; changes in urinary pattern (void before taking medications); or other persistent side effects.

Anesthesia and Critical Care Concerns/Other Considerations:

Tamsulosin may induce significant orthostatic hypotension with lightheadedness and possible loss of consciousness.

Cardiovascular Considerations:

Tamsulosin should not be used as an antihypertensive agent despite its alpha-blocking properties. It may induce significant orthostatic hypotension with lightheadedness and possible loss of consciousness.

Dental Health: Effects on Dental Treatment:

No significant effects or complications reported

Dental Health: Vasoconstrictor/Local Anesthetic Precautions:

No information available to require special precautions

Mental Health: Effects on Mental Status:

Dizziness is common; may cause drowsiness or insomnia

Mental Health: Effects on Psychiatric Treatment:

None reported

Dosage Forms:

Capsule, as hydrochloride: 0.4 mg

International Brand Names:

Aclosan® (AR); Alna® (AT, DE, NO); Expros® (FI); Flomax® (AU, CA, GB, NZ, TR, ZA); Harnal® (ID, JP, TH); Josir® (FR); Omic® (BE, LU); Omix® (CH, FR); Omnic® (AR, BG, BR, CL, CO, CZ, DE, DK, ES, FI, HU, IE, IL, IT, JP, NL, NO, NZ, PL, PT, RO, RU, SI); Pradif® (CH, IT, PT); Reduprost® (AR); Secotex® (AR, BR, CL, CO, EC, MX); Urimax® (IN); Urolosin® (ES)

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