Prazosin
2257429
217251774
2008-06-05T06:26:32Z
Sbmehta
765172
capitalization
{{drugbox
| IUPAC_name = [4-(4-amino-6,7-dimethoxy-quinazolin-2-yl) piperazin-1-yl]-(2-furyl)methanone
| image = Prazosin.svg
| width = 300
| CAS_number = 19216-56-9
| ATC_prefix = C02
| ATC_suffix = CA01
| ATC_supplemental =
| PubChem = 4893
| DrugBank = APRD00020
| C = 19 | H = 21 | N = 5 | O = 4
| molecular_weight = 383.401 g/mol
| bioavailability =
| protein_bound = 97%
| metabolism =
| elimination_half-life = 2–3 hours
| pregnancy_category =
| legal_UK = POM
| routes_of_administration = Oral
}}
'''Prazosin''', trade names '''Minipress''','''Vasoflex''' and '''Hypovase''', is a [[medication]] used to treat high blood pressure ([[hypertension]]). It belongs to the class of [[alpha-adrenergic blocker]]s, which lower blood pressure by relaxing blood vessels. Specifically, prazosin is selective for the [[alpha-1 receptor]]s on vascular smooth muscle. These receptors are responsible for the vasoconstrictive action of [[norepinephrine]], which in turn raises blood pressure. By blocking these receptors, prazosin reduces blood pressure.
Prazosin is orally active and has a minimal effect on cardiac function due to its alpha-1 receptor selectivity. Unlike other less selective alpha blockers that also block presynaptic alpha-2 receptors, it doesn't prevent inhibition of norepinephrine release. Uninhibited norepinephrine release usually causes an increased reflex [[tachycardia]] through the [[Sympathetic nervous system|sympathetic]] [[baroreflex]] response that, in turn, increases cardiac output. However, when blood pressure drops, the body does not increase cardiac output to compensate for the loss in pressure when a person takes prazosin.
Prazosin is also useful in treating urinary hesitancy associated with [[benign prostatic hyperplasia|prostatic hyperplasia]] by blocking alpha-1 receptors, which control constriction of both the [[prostate]] and [[ureters]].
Side effects of prazosin include [[orthostatic hypotension]], [[fainting|syncope]], and [[nasal congestion]]. The orthostatic hypotension and syncope are associated with the body's poor ability to control blood pressure without active alpha-adrenergic receptors. Patients on prazosin should be told not to stand up too quickly, since their poor baroreflex may cause them to faint as all their blood rushes to their feet. The nasal congestion is due to dilation of vessels in the nasal [[mucosa]]. One phenomenon associated with prazosin is known as the "[[first dose response]]", in which the side effects of the drug, especially orthostatic hypotension, are especially pronounced after the first dose. Another common side effect of prazosin (and doxazosin) is [[priapism]].[http://www.pubmedcentral.nih.gov/pagerender.fcgi?artid=1596841&pageindex=1][http://linkinghub.elsevier.com/retrieve/pii/S0022534705680184].
This medication has shown to be effective in treating severe nightmares in children, associated with PTSD symptoms.{{Fact|date=February 2008}}
Also veterans have been treated successfully at the Oregon VA for sleep disturbance related to PTSD. Doses are lower for this purpose than for control of blood pressure.{{Fact|date=February 2008}}
== Prazosin in scorpion stings ==
Since 1983 prazosin has revolutionized the management of severe scorpion stings.<ref name="Bawaskar1">{{cite journal
| author = Bawaskar HS, Bawaskar PH
| title = Utility of scorpion antivenin vs prazosin in the management of severe ''Mesobuthus tamulus'' (Indian red scorpion) envenoming at rural setting
| pmid = 17444339
| year=2007
| journal = J Assoc Physicians India
| month = Jan
| volume = 55
| issue =
| pages = 14–21
}}</ref>
== References ==
{{reflist}}
{{Antihypertensives and diuretics}}
[[Category:Alpha blockers]]
[[Category:Furans]]
{{pharma-stub}}
[[de:Prazosin]]
[[fr:Prazosine]]
[[hr:Prazosin]]
[[ja:プラゾシン]]