Prazosin
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| AHFS/Drugs.com | Monograph |
| MedlinePlus | a682245 |
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| Routes of administration |
Oral |
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| Pharmacokinetic data | |
| Bioavailability | ~60% |
| Protein binding | 97% |
| Onset of action | 30–90 minutes |
| Biological half-life | 2–3 hours |
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| ECHA InfoCard | 100.038.971 |
| Chemical and physical data | |
| Formula | C19H21N5O4 |
| Molar mass | 383.401 g/mol |
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Prazosin, trade names Minipress, Vasoflex, Lentopres and Hypovase, is a sympatholytic drug used to treat high blood pressure, anxiety, and posttraumatic stress disorder (PTSD). It is an α1-blocker which acts as an inverse agonist at alpha-1 adrenergic receptors. These receptors are found on vascular smooth muscle, where they are responsible for the vasoconstrictive action of norepinephrine. They are also found throughout the central nervous system. As of 2013, prazosin is off-patent in the US, and the FDA has approved at least one generic manufacturer.
Prazosin is orally active and has a minimal effect on cardiac function due to its alpha-1 receptor selectivity. However, when prazosin is started, heart rate and contractility go up in order to maintain the pre-treatment blood pressures because the body has reached homeostasis at its abnormally high blood pressure. The blood pressure lowering effect becomes apparent when prazosin is taken for longer periods of time. The heart rate and contractility go back down over time and blood pressure decreases.
The antihypertensive characteristics of prazosin make it a second-line choice for the treatment of high blood pressure.
Prazosin is also useful in treating urinary hesitancy associated with prostatic hyperplasia, blocking alpha-1 receptors, which control constriction of both the prostate and urethra. Although not a first line choice for either hypertension or prostatic hyperplasia, it is a choice for patients who present with both problems concomitantly.
This medication has shown to be effective in treating severe nightmares in children and people with PTSD symptoms. Veterans have also been treated successfully at Seattle's VA Puget Sound Health Care System (VAPSHCS) for sleep disturbance related to PTSD. Doses are lower for this purpose than for control of blood pressure.
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Wikipedia