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Selective Alpha-1a Antagonist
Aka: 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 Fractures, despite selective nature
- Number needed to harm (NNH): 600 for fall-related hospitalizations, and 1600 for fall-related Fractures
- 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)