prazosin MINIPRESS

Class: Alpha 1 Antagonist/​Quinazoline
FDA Indications: Hypertension
Off-Label Use: PTSD, Raynaud Phenomenon, Pheochromocytoma, Congestive Heart Failure (in Conjunction With Cardiac Glycosides And Diuretics), Benign Prostatic Hyperplasia, PTSD-Related Nightmares
Forms: 1, 2, 5mg capsule
Dose Range: 1-15 mg/day
Starting: typically started at 1 mg qhs & is gradually ↑'d to 3-15 mg as tolerated
Stopping: Avoid sudden discontinuation, as this can result in rebound hypertension; patients should be cautioned accordingly

NAMI drug fact sheet

Serious Side Effects: Syncopal episodes (in ~1% @ doses >2mg)
Side Effects: headache, sedation/somnolence, dizziness, lightheadedness, weakness/asthenia, nausea, orthostatic hypotension, palpitations
1° MOA: Selective α1 antagonist
Target: α1
t½: 2.2 (3-3.7)° TMAX: 1-3°
Substrate of: BCRP, P-gp
Inhibits: ∅ ; Induces:
Active Metabolites:
  • - caution when co-prescribed with other medications that can lower blood pressure
  • - first known selective α1-blocker; discovered in the late 1960s, approved in 1976
  • - blocks α1 in arterioles & veins, lowering peripheral resistance & venous return to the heart
  • - a metaanalysis and multiple clinical trials have shown that prazosin ↓'s nightmares & ↑'s sleep in patients with PTSD
  • - often used adjunctively with SSRIs, though it may be considered as monotherapy
Special Populations

Category C—The limited human pregnancy experience and the animal reproduction data suggest low embryo-fetal risk.

There are no reports describing use during lactation. The manufacturer reports that small amounts are excreted into human milk which is c/w prazosin's molecular weight. The effects on a nursing infant from exposure to the drug from breast milk are unknown.

Elderly patients may be more sensitive to the hypotensive and adverse effects of prazosin.

No dosage adjustment necessary.

No specific recommendations are available for hepatic disease. Since prazosin is extensively metabolized, it is prudent to start with the lowest initial dosage (1 mg PO qhs).


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Last updated February 07 2019 16:52:18. Disclaimer: This website does not provide medical advice, nor is it a substitute for clinical judgment.