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Pharmacologic class: Alpha-adrenergic blocker
Therapeutic class: Anti-adrenergic
Pregnancy risk category B
Decreases smooth muscle contractions of prostate by binding to alpha1-adrenergic receptors. This action increases urine flow and reduces symptoms of benign prostatic hyperplasia (BPH).
Capsules: 0.4 mg
Indications and dosages
Adults: 0.4 mg/day P.O. after a meal. After 2 to 4 weeks, may increase to 0.8 mg/day.
• Hypersensitivity to drug or its components
Use cautiously in:
• concurrent use of other alpha-adrenergic blockers or strong CYP3A4 inhibitors (avoid use)
• concurrent use of moderate CYP3A4 inhibitors, strong or moderate CYP2D6 inhibitors, other cytochrome P450 inhibitors, warfarin, and in patients who are poor CYP2D6 metabolizers
• patients at increased risk for prostate cancer.
• Give 30 minutes after same meal each day.
CNS: dizziness, headache, asthenia, insomnia, drowsiness, syncope, vertigo
CV: orthostatic hypotension, chest pain
EENT: rhinitis, amblyopia, pharyngitis, sinusitis
GU: retrograde or diminished ejaculation, decreased libido
Musculoskeletal: back pain
Respiratory: increased cough
Other: tooth disorder, infection
Drug-drug. Cimetidine: increased tamsulosin blood level, greater risk of toxicity
Doxazosin, prazosin, terazosin: increased risk of hypotension
Ketoconazole (strong CYP3A4 inhibitor), paroxetine (strong CYP2D6 inhibitor): increased tamsulosin Cmax and area under the curve
Drug-behaviors. Alcohol use: increased risk of hypotension
• Monitor blood pressure. Stay alert for orthostatic hypotension.
• Tell patient to take 30 minutes after same meal each day.
• Instruct patient not to chew or open capsule. Advise him to swallow it whole.
• Tell patient to move slowly when sitting up or standing, to avoid dizziness or light-headedness from sudden blood pressure decrease.
• Caution patient to avoid hazardous activities on first day of therapy.
• Inform patient that drug may cause abnormal ejaculation. Advise him to discuss this issue with prescriber.
• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs and behaviors mentioned above.