Pharm
Selective Alpha-1a Antagonist
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Selective Alpha-1a Antagonist
, Tamsulosin, Flomax, Alfuzosin, Uroxatral, Silodosin, Rapaflo
See Also
Postsynaptic Alpha Adrenergic Antagonist
Benign Prostatic Hyperplasia
Indications
Benign Prostatic Hypertrophy
Ureterolithiasis
Mechanism
Benign Prostatic Hypertrophy
Background
Non-Selective
Postsynaptic Alpha Adrenergic Antagonist
(
Terazosin
,
Doxazosin
,
Prazosin
)
Relatively weak antihypertensives, were often used for BPH
Selective Alpha-1a Antagonist
Developed for specific Alpha-1a activity with minimal antihypertensive effects
Rapid relaxation of
Smooth Muscle
tone
Bladder
neck
Prostate
Capsule
Prostatic
Urethra
Relieves symptoms of urinary obstruction
May see full effect within 2 weeks
Does not effect size of
Prostate
(unlike
Proscar
)
Preparations
Selective Alpha-1a Antagonists (
Prostate
specific agents)
Precautions
Still cause
Orthostatic Hypotension
, fall risk,
Head Trauma
and
Fracture
s, despite selective nature
Number needed to harm (NNH): 600 for fall-related hospitalizations, and 1600 for fall-related
Fracture
s
Welk (2015) BMJ 351:h5398 +PMID:26502947 [PubMed]
Alfuzosin (Uroxatral, generic)
Dose: 10 mg once daily
Contraindicated in moderate to severe liver disease (and
Exercise
caution in renal disease)
Silodosin (Rapaflo)
Dose: 8 mg daily with food (4 mg daily if GFR 30-50 ml/min)
Contraindicated when GFR <30 ml/min or severe liver disease (
Child-Pugh Score
10 or more)
Tamsulosin (Flomax, generic)
Dose 0.4 mg orally daily (maximum 0.8 mg/day)
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