QuickView for Prazosin (compound)

Summary
General Info

PubChem

PubChem Compound 450782

Name:	Prazosin
PubChem Compound ID:	450782
Description:	A selective adrenergic alpha-1 antagonist used in the treatment of HEART FAILURE; HYPERTENSION; PHEOCHROMOCYTOMA; RAYNAUD DISEASE; PROSTATIC HYPERTROPHY; and URINARY RETENTION.
Molecular formula:	C₁₉H₂₁N₅O₄
Molecular weight:	382.402 g/mol
Synonyms:	MOLI001320

DrugBank

Identification

Name:	Prazosin
Name (isomeric):	DB00457
Drug Type:	small molecule
Description:	A selective adrenergic alpha-1 antagonist used in the treatment of HEART FAILURE; HYPERTENSION; PHEOCHROMOCYTOMA; RAYNAUD DISEASE; PROSTATIC HYPERTROPHY; and URINARY RETENTION.
Synonyms:	Prazosin HCl; Prazosina [INN-Spanish]; Prazocin; Prazosin Hydrochloride; Prazosine [INN-French]; Prazosinum [INN-Latin]
Brand:	Minipress Xl, Lentopres, Minipress, Furazosin, Vasoflex
Brand name mixture:	Minizide(prazosin + polythiazide)
Category:	Alpha-adrenergic Blocking Agents, Adrenergic alpha-Antagonists, Antihypertensive Agents
CAS number:	19216-56-9

Pharmacology

Indication:	For treatment of hypertension, symptomatic benign prostatic hyperplasia, and severe congestive heart failure. May also be used alone or in combination with β-blockers in the preoperative management of signs and symptoms of pheochromocytoma.
Pharmacology:	Prazosin is an alpha-adrenergic blocking agent used to treat hypertension and benign prostatic hyperplasia. Accordingly, Prazosin is a selective inhibitor of the alpha1 subtype of alpha adrenergic receptors. In the human prostate, Prazosin antagonizes phenylephrine (alpha1 agonist)-induced contractions, in vitro, and binds with high affinity... show more » Prazosin is an alpha-adrenergic blocking agent used to treat hypertension and benign prostatic hyperplasia. Accordingly, Prazosin is a selective inhibitor of the alpha1 subtype of alpha adrenergic receptors. In the human prostate, Prazosin antagonizes phenylephrine (alpha1 agonist)-induced contractions, in vitro, and binds with high affinity to the alpha1c adrenoceptor, which is thought to be the predominant functional type in the prostate. Studies in normal human subjects have shown that Prazosin competitively antagonized the pressor effects of phenylephrine (an alpha1 agonist) and the systolic pressor effect of norepinephrine. The antihypertensive effect of Prazosin results from a decrease in systemic vascular resistance and the parent compound Prazosin is primarily responsible for the antihypertensive activity. show less «
Mechanism of Action:	Prazosin acts by inhibiting the postsynaptic alpha(1)-adrenoceptors on vascular smooth muscle. This inhibits the vasoconstrictor effect of circulating and locally released catecholamines (epinephrine and norepinephrine), resulting in peripheral vasodilation.
Absorption:	Well-absorbed from gastrointestinal tract; bioavailability is variable (50 to 85%).
Protein binding:	97%
Biotransformation:	Primarily hepatic. Several metabolites have been identified in humans and animals (6- O -demethyl, 7- O -demethyl, 2-[1-piperazinyl]-4-amino-6, 7-dimethoxyquinazoline, 2,4-diamino-6,7-dimethoxyquinazoline).
Route of elimination:	Animal studies indicate that prazosin hydrochloride is extensively metabolized, primarily by demethylation and conjugation, and excreted mainly via bile and feces. Less extensive human studies suggest similar metabolism and excretion in man.
Half Life:	2-3 hours
Affected organisms:	Humans and other mammals

Interactions

Food interaction:

Avoid alcohol.

Take without regard to meals.

Avoid natural licorice.

Drug interaction:

Atenolol	Risk of hypotension at the beginning of therapy
Vardenafil	Additive hypotensive effects of the PDE5 inhibitor, Vardenafil, and alpha1-blocker, Prazosin, may occur. Monitor for hypotension during concomitant therapy.
Pindolol	Risk of hypotension at the beginning of therapy
Dabigatran etexilate	P-Glycoprotein inducers such as prazosin may decrease the serum concentration of dabigatran etexilate. This combination should be avoided.
Metoprolol	Risk of hypotension at the beginning of therapy

Atenolol	Risk of hypotension at the beginning of therapy
Vardenafil	Additive hypotensive effects of the PDE5 inhibitor, Vardenafil, and alpha1-blocker, Prazosin, may occur. Monitor for hypotension during concomitant therapy.
Pindolol	Risk of hypotension at the beginning of therapy
Dabigatran etexilate	P-Glycoprotein inducers such as prazosin may decrease the serum concentration of dabigatran etexilate. This combination should be avoided.
Metoprolol	Risk of hypotension at the beginning of therapy
Labetalol	Risk of hypotension at the beginning of therapy
Carteolol	Risk of hypotension at the beginning of therapy
Bevantolol	Risk of hypotension at the beginning of therapy
Penbutolol	Risk of hypotension at the beginning of therapy
Digoxin	Prazosin increases the effect of digoxin
Carvedilol	Risk of hypotension at the beginning of therapy
Treprostinil	Additive hypotensive effect. Monitor antihypertensive therapy during concomitant use.
Propranolol	Risk of hypotension at the beginning of therapy
Acebutolol	Risk of hypotension at the beginning of therapy
Practolol	Risk of hypotension at the beginning of therapy
Tadalafil	Tadalafil may enhance the hypotensive effect of Prazosin. Monitor for hypotension during concomitant therapy.
Nadolol	Risk of hypotension at the beginning of therapy
Timolol	Risk of hypotension at the beginning of therapy
Sotalol	Risk of hypotension at the beginning of therapy
Verapamil	Risk of hypotension at the beginning of therapy
Oxprenolol	Risk of hypotension at the beginning of therapy
Esmolol	Risk of hypotension at the beginning of therapy
Bisoprolol	Risk of hypotension at the beginning of therapy
Betaxolol	Beta-Blockers such as betaxolol may enhance the orthostatic hypotensive effect of Alpha1-Blockers such as prazosin. The risk associated with ophthalmic products is probably less than systemic products. Exercise caution if an alpha1-blocker is added to existing beta-blocker therapy. Monitor for hypotension during first few days of concomitant therapy. A priori reduction in alpha1-blocker (especially systemic) dose may be warranted. Administering the first dose of systemic agents at bedtime may help minimize risk of severe hypotension. The risk associated with the use of ophthalmic products in either interacting group is probably less than that associated with systemic agents. If the alpha1-blocker is being used to treat BPH, consider using tamsulosin since its alpha1-A selectivity is least likely to cause hypotension.
Tamsulosin	Concomitant use of alpha1-adrenergic antagonists, Tamsulosin and Prazosin, may result in additive antihypertensive effects. Combination therapy is not recommended.

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Targets

Alpha-1A adrenergic receptor

Alpha-1B adrenergic receptor

Alpha-1D adrenergic receptor

Potassium voltage-gated channel subfamily H member 2

Potassium voltage-gated channel subfamily H member 6

Potassium voltage-gated channel subfamily H member 7

Enzymes

Cytochrome P450 1A1

Transporters

Solute carrier family 22 member 2

Solute carrier family 22 member 1

Solute carrier family 22 member 3

Multidrug resistance protein 1

ATP-binding cassette sub-family G member 2

Carriers

Alpha-1-acid glycoprotein 1