prazosin (Minipress, Deprazolin)
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Introduction
Tradename: Minipress.
Indications
- benign prostatic hypertrophy
- hypertension
- Raynaud's disease
- severe congestive heart failure in connection with diuretics & digoxin
- nightmares resulting from PTSD[5]; maybe not[7]
Contraindications
Dosage
- start* 1 mg PO QHS, then BID/TID
- maximum: 20-40 mg/day
- do NOT withdraw therapy abruptly, taper dose
- BPH
Tabs: 1,2 5 mg.
* The 1st dose of prazosin may cause hypotension & syncope, thus it should be given before bedtime.
Pharmacokinetics
- oral bioavailability is 60%
- plasma 1/2life is 2-4 hours
- metabolized in the liver
- excreted in the urine
elimination via liver
1/2life = 2-4 hours
Adverse effects
- common (> 10%)
- less common (1-10%)
- uncommon (< 1%)
- other
- reflex tachycardia
- development of tolerance
- gastrointestinal distress
- 1st dose syncope
- impotence & priapism are rare
- drug adverse effects of alpha-1 adrenergic receptor antagonists
- drug adverse effects of antihypertensive agents
Drug interactions
- beta-blockers enhance acute postural hypotensive reactions
- verapamil increases serum prazosin levels
- clonidine: decreases antihypertensive effect
- drug interaction(s) of beta-adrenergic receptor antagonists with prazosin
- drug interaction(s) of phosphodiesterase-5-inhibitors with alpha-1-adrenergic receptor antagonists
- drug interaction(s) of loop diuretics with alpha-1 adrenergic receptor antagonist
- drug interaction(s) of NSAIDs & antihypertensives
Laboratory
Mechanism of action
- alpha-1 adrenergic receptor antagonist
- reduces total peripheral resistence through both arterial & venous dilation
- minimal changes in heart rate & cardiac output
- increases urine flow in BPH by relaxing smooth muscle tone in the bladder neck of the prostate
- increases HDL cholesterol
- may improve glucose tolerance
- may reduce left ventricular hypertrophy with long-term therapy
More general terms
Component of
References
- ↑ The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- ↑ Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
- ↑ Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 474
- ↑ Kaiser Permanente Northern California Regional Drug Formulary, 1998
- ↑ 5.0 5.1 Dierks MR et al, Prozosin treatment of nightmares related to postraumatic stress disorder. Ann Pharmacother 2007, 41:1013 PMID: https://www.ncbi.nlm.nih.gov/pubmed/17504838
- ↑ Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
- ↑ 7.0 7.1 7.2 Raskind MA et al. Trial of prazosin for post-traumatic stress disorder in military veterans. N Engl J Med 2018 Feb 8; 378:507 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/29414272 <Internet> http://www.nejm.org/doi/10.1056/NEJMoa1507598
Ressler KJ. Alpha-adrenergic receptors in PTSD - Failure or time for precision medicine? N Engl J Med 2018 Feb 8; 378:575 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/29414268 <Internet> http://www.nejm.org/doi/10.1056/NEJMe1716724