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Alpha Adrenergic Antagonist
Aka: Alpha Adrenergic Antagonist, Peripheral Alpha-1 Adrenergic Antagonist, Postsynaptic Alpha Adrenergic Antagonist, Alpha Adrenergic Receptor Blocker, Prazosin, Minipress, Terazosin, Hytrin, Doxazosin, Cardura
- See Also
- Selective Alpha-1a Antagonist
- Sympathetic Nervous System
- Alpha Adrenergic Receptor
- Presynaptic Adrenergic Release Inhibitor
- Indications
- Hypertension (non-selective agents)
- Benign Prostatic Hypertrophy
- Pharmacokinetics
- Agents are highly protein bound (>90%)
- Mechanism: General and Antihypertensive Effects
- See Alpha Adrenergic Receptor (Alpha-1 antagonist)
- Peripheral Alpha-1 Adrenergic Antagonists
- Arterial and Venous Vasodilation
- Mechanism: Benign Prostatic Hypertrophy
- Preparations used in Benign Prostatic Hypertrophy
- See Selective Alpha-1a Antagonist (Tamsulosin, Alfuzosin, Silodosin)
- Terazosin (Hytrin)
- Doxazosin (Cardura)
- Prazosin (Minipress)
- 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: Non-Selective Agents
- Terazosin (Hytrin)
- Dose: 1 mg orally at bedtime (Maximum 20 mg/day)
- Doxazosin (Cardura)
- Dose: 1 mg orally at bedtime (Maximum 16 mg/day)
- Prazosin (Minipress)
- Dose: 1 mg PO bid-tid (Maximum 40 mg/day)
- Terazosin and Doxazosin are preferred instead (once daily dosing at similar cost)
- Phenoxybenzamine (Dibenzyline)
- Dose: 10 mg PO bid (Maximum 120 mg/day)
- Terazosin and Doxazosin are preferred instead (once daily dosing at similar cost)
- Preparations: Selective Alpha-1a Antagonists (Prostate specific agents)
- See Selective Alpha-1a Antagonists
- Alfuzosin (Uroxatral, generic)
- Silodosin (Rapaflo)
- Tamsulosin (Flomax, generic)
- Preparations: Combination Alpha-Beta Antagonists
- Labetalol (Trandate)
- Carvedilol (Coreg)
- Adverse Effects (Incidence: 7 to 9%)
- Dose at bedtime
- Slowly titrate to reduce side effects (esp. Orthostatic Hypotension)
- Cardiovascular adverse effects (also occurs with selective agents, albeit less often)
- Postural or Orthostatic Hypotension
- Common with first dose (may be severe)
- Exacerbated by Hyponatremia
- Dizziness
- Associated with fall risk and secondary Fracture risk
- Other adverse effects
- Fatigue
- Asthenia
- Xerostomia
- Headache
- Nightmares
- Sexual Dysfunction
- Precautions
- Avoid using as monotherapy for Hypertension
- Higher risk of CVA and CHF compared with other agents
- (2000) JAMA 283:1967-75 [PubMed]
- References
- Aldridge (1996) Lancet 348:602
- http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(05)64801-5/abstract
- (1994) Med Lett Drugs Ther 36: 15 [PubMed]
- (1997) Med Lett Drugs Ther 39: 1011 [PubMed]
- Lee (2000) Ann Pharmacother 34:188-99 [PubMed]