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WHAT IS IT?
Tamsulosin (Flowmax) is a α1 selective alpha blocker. Compared to other α1-antagonists this medication is selective for α1A,D receptors (found in the prostate) vs. the α1B receptors found on the vasculature (although they can still bind these receptors to some degree).
WHEN DO WE USE IT?
Benign prostatic hyperplasia (BPH)/urinary retention: given this medications activity in blocking α1 adrenergic signaling, it will cause smooth muscle relaxation (of the prostate). This will help increase urinary outflow in patients with BPH.
WHEN DO WE AVOID USING IT?
For treating hypertension: this medication (due to its selectivity) is not a very practical option for treating hypertension.
HOW IS IT ADMINISTERED?
Administer orally: the medication should be taken one daily, 30 minutes after the same meal each day. The capsule should be swelled intact (do not open, crush, or chew the capsules).
HOW IS IT DOSED?
Dosing information source: Flomax
Initial dose: 0.4 mg once a day is the starting dose. This should be tried for 2-4 weeks to assess for a response.
Dose increase: if a higher dose is needed, the dosage may be increased to 0.8 mg once a day.
If dose is interrupted: patients (even those on a 0.8 mg daily dose) are unable to take their medication for more then a few days, they should start back on a 0.4 mg per day dosage (to re-adjust to the medication).
Hepatic/renal impairment: dosing adjustment not needed in patients with hepatic impairment or mild to severe renal impairment.
WHAT ARE THE SIDE EFFECTS/TOXICITY?
With the first dose patients may experience orthostatic hypotension, dizziness, and headache.
Priapism is a rare side effect but this should be treated promptly.
FURTHER READING
Page Updated: 08.05.2016