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  Tamulosin (Flomax)
Author: Donna Karasic, PharmD Last modified: February 24, 2002


  • Benign Prostatic Hyperplasia


  • 0.4 mg once a day
  • For patients who fail to respond to 0.4 mg after 2-4 weeks, the dose may be increased to 0.8 mg once a day
  • If tamsulosin is interrupted for several days, therapy should be restarted with the 0.4 mg once a day dose


  • Time to peak concentration is 4 to 8 hours
  • Bioavailability approaches 100% under fasting conditions
  • Metabolized extensively by the liver
  • 76% of dose is renally excreted; less than 10% of a dose is excreted as unchanged drug
  • 21% of the dose is excreted in the feces
  • Elimination half-life is 9-13 hrs; in elderly patients (greater than 65 yrs of age) the elimination half-life is 14-15 hrs


  • Chest pain (4%)
  • Dizziness (3% to 17%)
  • Headache (2% to 21%)
  • Asthenia (8%)
  • Somnolence (3% to 4%)
  • Insomnia (1% to 2%)
  • Nausea (2% to 4%)
  • Diarrhea (4% to 6%)
  • Abnormal ejaculation (8% to 18%) and decreased libido (1% to 2%)
  • Rhinitis (13% to 17%), Pharyngitis (5% to 6%), Cough (3% to 4%), Sinusitis (2% to 4%)
  • Rash (7%)
  • Back Pain (7% to 8%)


  • Hypersensitivity to tamulosin


  • Beta blockers
  • Cimetidine
  • Warfarin


  • 0.4mg capsule


  • Tamulosin has a high degree of selectivity and potency as a postsynaptic alpha-1 adrenoceptor antagonist in the genitourinary tract
  • It has been shown to bind preferentially to alpha-1A adrenoceptor subtype in the prostate and is responsible for contraction of prostate smooth muscle
  • Tamulosin has been shown to significantly increase urinary flow rates and decrease outflow obstruction and irritation symptoms associated with benign prostatic hypertrophy
  • Carcinoma of the prostate and benign prostatic hyperplasia may cause the same symptoms. Prostate cancer should be ruled out prior to treatment.
  • Caution patients of dizziness, vertigo, orthostatic hypotension and syncope ("First-dose" effect)
  • Use general anesthesia with caution since in combination with tamulosin may cause blood pressure instability
  • Tamsulosin bioavailability is enhanced by administration under fasting conditions
  • Tamsulosin should be taken 30 minutes after the same meal each day
  • Tamsulosin does not significantly affect PSA levels in men with benign prostatic hyperplasia
  1. Hutchinson TA & Shahan DR (Eds) ;  Tamulosin ;  MICROMEDEX Healthcare Series: MICROMEDEX, Greenwood Village, Colorado (Edition expires 3-2202)

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