Title: Doxazosin
CAS Registry Number: 74191-85-8
CAS Name: 1-(4-Amino-6,7-dimethoxy-2-quinazolinyl)-4-[(2,3-dihydro-1,4-benzodioxin-2-yl)carbonyl]piperazine
Additional Names: 4-amino-2-[4-(1,4-benzodioxan-2-carbonyl)piperazin-1-yl]-6,7-dimethoxyquinazoline
Manufacturers' Codes: UK-33274
Molecular Formula: C23H25N5O5
Molecular Weight: 451.48
Percent Composition: C 61.19%, H 5.58%, N 15.51%, O 17.72%
Literature References: Selective a1-adrenergic blocker related to prazosin, q.v. Prepn: S. F. Campbell, DE 2847623; idem, US 4188390 (1979, 1980 both to Pfizer). Cardiovascular pharmacology: P. B. Timmermans et al., Arch. Int. Pharmacodyn. Ther. 245, 218 (1980). HPLC determn in plasma: M. G. Cowlishaw, J. R. Sharman, J. Chromatogr. 344, 403 (1985). Clinical pharmacokinetics: H. L. Elliott et al., Br. J. Clin. Pharmacol. 13, 699 (1982). Symposia on pharmacology and clinical efficacy in hypertension: Br. J. Clin. Pharmacol. 21, Suppl. 1, 1S-92S (1986); Am. J. Cardiol. 59, 1G-104G (1987). Review of clinical trials in benign prostatic hypertrophy: C. G. Roehrborn, R. L. Siegel, Urology 48, 406-415 (1996).
Derivative Type: Hydrochloride
Molecular Formula: C23H25N5O5.HCl
Molecular Weight: 487.94
Percent Composition: C 56.61%, H 5.37%, N 14.35%, O 16.39%, Cl 7.27%
Properties: Crystals, mp 289-290°.
Melting point: mp 289-290°
Derivative Type: Methanesulfonate
CAS Registry Number: 77883-43-3
Additional Names: Doxazosin mesylate
Manufacturers' Codes: UK-33274-27
Trademarks: Alfadil (Pfizer); Alfamedin (Kade); Benur (Pfizer); Cardenalin (Pfizer); Cardular (Pfizer); Cardura (Pfizer); Carduran (Pfizer); Diblocin (AstraZeneca); Doxamax (Esparma); Zoxan (Pfizer)
Molecular Formula: C23H25N5O5.CH3SO3H
Molecular Weight: 547.58
Percent Composition: C 52.64%, H 5.34%, N 12.79%, O 23.37%, S 5.86%
Therap-Cat: Antihypertensive; in treatment of benign prostatic hypertrophy.
Keywords: a-Adrenergic Blocker; Antihypertensive; Quinazoline Derivatives; Antiprostatic Hypertrophy.
Doxefazepam Doxenitoin Doxepin Doxercalciferol Doxifluridine

Doxazosin ball-and-stick.png
Systematic (IUPAC) name
Clinical data
Trade names Cardura
AHFS/ monograph
MedlinePlus a693045
Legal status Prescription only
Routes oral
Pharmacokinetic data
Bioavailability 65%
Protein binding 98%
Metabolism Hepatic
Half-life 22 hours
CAS number 74191-85-8 YesY
ATC code C02CA04
PubChem CID 3157
DrugBank DB00590
ChemSpider 3045 YesY
UNII NW1291F1W8 YesY
KEGG D07874 YesY
Chemical data
Formula C23H25N5O5 
Mol. mass 451.475 g/mol
 YesY (what is this?)  (verify)

Doxazosin mesylate, a quinazoline compound sold by Pfizer under the brand names Cardura and Carduran, is an α1-selective alpha blocker used to treat high blood pressure and urinary retention associated with benign prostatic hyperplasia (BPH).

On February 22, 2005, the US FDA approved a sustained release form of doxazosin, to be marketed as Cardura XL.

It is an alpha-1 adrenergic receptor blocker that inhibits the binding of norepinephrine (released from sympathetic nerve terminals) to the alpha-1 receptors on the membrane of vascular smooth muscle cells. The primary effect of this inhibition is relaxed vascular smooth muscle tone (vasodilation), which decreases peripheral vascular resistance, leading to decreased blood pressure.

Doxazosin and similar medications like prazosin have been found to help reduce the intensity of and/or stop posttraumatic stress disorder night terrors and nightmares. The full reasoning of this effect is not understood.

In Egypt, tablet formulation sold as Duracin produced by Biopharm group for research and the drug industry, Dosin by Eipico and Doxazocine by Multi-Apex.