Doxazosin

Brand names: Cardura®, Cardura® XL

Chemical formula:

Drug Forms:
• Doxazosin extended-release tablets (below)
• Doxazosin Mesylate Oral tablet
• Doxazosin Mesylate Oral tablet, extended-release

Espa�ol:
• Doxazosín Mesilato, Tableta oral
• Doxazosín Mesilato, Tableta oral de liberación prolongada

Doxazosin extended-release tablets

What are doxazosin extended-release tablets?

DOXAZOSIN (Cardura® XL) is an antihypertensive. Doxazosin lowers, but does not cure, high blood pressure. It works by relaxing your blood vessels. It also can be used to treat enlargement of the prostate gland in men. Generic doxazosin extended-release tablets are not available.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of the following conditions:
• kidney disease
• liver disease
• low blood pressure
• an unusual or allergic reaction to doxazosin, other medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
• breast-feeding

How should I take this medicine?

Take doxazosin extended-release tablets by mouth. Follow the directions on the prescription label. Swallow the tablets whole with a drink of water; do not cut, crush, or chew. Take your doses at regular intervals even if you feel better. Do not take your medicine more often than directed. Do not stop taking except on your prescriber's advice.

Contact your pediatrician or health care professional regarding the use of this medicine in children. Special care may be needed.

What if I miss a dose?

What drug(s) may interact with doxazosin?

Do not take doxazosin if you are taking the following medications:
• other alpha-blockers such as alfuzosin, phentolamine, phenoxybenzamine, prazosin, tamsulosin, terazosin

Doxazosin may also interact with the following medications:
• antiinflammatory drugs (NSAIDs, such as ibuprofen)
• dopamine
• female hormones, including contraceptive or birth control pills
• medicines for colds and breathing difficulties
• medicines for high blood pressure
• metaraminol
• methoxamine
• monoamine oxidase inhibitors (Azilect®, Eldepryl®, Emsam®, Marplan®, Nardil®, Parnate®, Zelapar™)
• sildenafil (doses of sildenafil higher than 25 mg should be taken at least 4 hours apart from taking doxazosin)
• tadalafil
• vardenafil
• water pills

Tell your prescriber or health care professional about all other medicines you are taking, including nonprescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your prescriber or health care professional before stopping or starting any of your medicines.

What should I watch for while taking doxazosin?

Check your blood pressure regularly. Ask your prescriber or health care professional what your blood pressure should be and when you should contact him or her.

You may feel drowsy or dizzy. Do not drive, use machinery, or do anything that requires mental alertness until you know how doxazosin affects you. To reduce the risk of dizzy or fainting spells, do not sit or stand up quickly. Avoid alcoholic drinks; they can make you more drowsy, and can increase flushing and rapid heartbeats. Take doxazosin at bedtime to lessen the effects of drowsiness and dizziness, but be careful if you have to get up during the night. Drowsiness and dizziness are more likely to occur after the first dose, after an increase in dose, or during hot weather or exercise. Dizziness can decrease once your body adjusts to this medicine.

Although extremely rare in men taking doxazosin, contact you health care provider immediately if you experience prolonged and painful erection of the penis which is unrelated to sexual activity (priapism). If not brought to immediate medical attention, priapism can lead to permanent erectile dysfunction (impotence).

Do not take nonprescription medicine for weight-loss without asking your prescriber or health care professional. Also, do not take cough and cold, hay fever, or sinus medications without asking your prescriber or health care professional.

If you are going to have surgery, tell your prescriber or health care professional that you are taking doxazosin.

If you are taking Cardura® XL, you may notice the empty shell of the tablet in your stool.

What side effects may I notice from taking doxazosin?

Side effects that you should report to your prescriber or health care professional as soon as possible:
Rare or uncommon:
• difficulty breathing, shortness of breath
• prolonged painful erection of the penis (priapism)
More common:
• dizzy or drowsy
• fainting spells
• numbness in hands or feet
• palpitations or pounding heart, irregular heartbeat
• swelling of the legs or ankles

Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):
• headache
• nausea
• unusual tiredness

Where can I keep my medicine?

Keep out of the reach of children in a container that small children cannot open.

Store at room temperature between 15—30 degrees C (59—86 degrees F). Throw away any unused medicine after the expiration date.

Last updated: 7/1/2002

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

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trade name: Cardura; drug class: peripheral α-adrenergic blocker; action: peripheral blood vessels are dilated, peripheral resistance lowered, reduction in blood pressure reduced; uses: hypertension.

Doxazosin

Systematic (IUPAC) name
(RS)-2-{4-[(2,3-dihydro-1,4-benzodioxin-2-yl)carbonyl]piperazin-1-yl}-6,7-dimethoxyquinazolin-4-amine
Clinical data
Trade names	Cardura
AHFS/Drugs.com	monograph
MedlinePlus	a693045
Pregnancy cat.	?
Legal status	℞ Prescription only
Routes	oral
Pharmacokinetic data
Bioavailability	65%
Protein binding	98%
Metabolism	Hepatic
Half-life	22 hours
Identifiers
CAS number	74191-85-8
ATC code	C02CA04
PubChem	CID 3157
DrugBank	APRD00474
ChemSpider	3045 Y
UNII	NW1291F1W8 Y
KEGG	D07874 Y
ChEBI	CHEBI:4708 Y
ChEMBL	CHEMBL707 Y
Chemical data
Formula	C23H25N5O5
Mol. mass	451.475 g/mol
SMILES	eMolecules & PubChem
InChI InChI=1S/C23H25N5O5/c1-30-18-11-14-15(12-19(18)31-2)25-23(26-21(14)24)28-9-7-27(8-10-28)22(29)20-13-32-16-5-3-4-6-17(16)33-20/h3-6,11-12,20H,7-10,13H2,1-2H3,(H2,24,25,26) Y Key:RUZYUOTYCVRMRZ-UHFFFAOYSA-N Y
Y(what is this?)  (verify)

Doxazosin mesylate, a quinazoline compound sold by Pfizer under the brand names Cardura and Carduran, is an α1a-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.

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.

Efficacy

In March 2000, the ALLHAT study stopped its arm of the trial looking at alpha blockers, because doxazosin (Cardura) was less effective than a simple diuretic, and because patients on Cardura had a 25% higher rate of cardiovascular disease and twice the rate of congestive heart failure as patients on diuretics.^[1] Pfizer, aware of the results before publication, launched a sophisticated damage-control campaign in early 2000, and sales were largely unaffected, despite the dangers highlighted by the study.^[2]

Recent Studies have given new rise to a preference for Doxazosin as a BPH Drug, as it was found to treat erectile dysfunction (ED). The company’s own study did not yield as statistically significant results; however, Doxazosin does show promise for men with BPH and ED.^[3]

References

1. ^ Piller LB, Davis BR, Cutler JA, et al. (November 2002). "Validation of Heart Failure Events in the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) Participants Assigned to Doxazosin and Chlorthalidone". Curr Control Trials Cardiovasc Med 3 (1): 10. doi:10.1186/1468-6708-3-10. PMC 149403. PMID 12459039. 
2. ^ "Marketing: Spin doctors soft pedal data on antihypertensives". BMJ. 2003-01-18. http://www.bmj.com/cgi/content/full/326/7381/170/DC1. Retrieved 2008-05-26. 
3. ^ "Antihypertensive Drugs and Patients With Erectile Dysfunction". http://www.medscape.com/viewarticle/439675_3. 

External links

• Information about Cardura from rxlist.com
• Cardura XL product website, run by Pfizer

v · d · eSympatholytic (and closely related) antihypertensives (C02) Sympatholytics (antagonize α-adrenergic vasoconstriction) Central α2 agonist Clonidine • Guanfacine • Methyldopa # Adrenergic release inhibitors Bethanidine • Bretylium • Debrisoquine • Guanadrel • Guanazodine • Guanethidine • Guanoclor • Guanoxan • Guanazodine • Guanoxabenz • Guanoxan Imidazoline receptor agonist Moxonidine • Rilmenidine Ganglion-blocking/nicotinic antagonist Mecamylamine • Pentolinium • Trimethaphan Peripheral Indirect MAOI Pargyline Adrenergic uptake inhibitor Rescinnamine • Reserpine Tyrosine hydroxylase inhibitor Metirosine Direct α1 blockers Prazosin • Indoramin • Trimazosin • Doxazosin • Urapidil Non-selective α blocker Phentolamine Other antagonists Serotonin antagonist Ketanserin Endothelin antagonist (for PH) dual (Bosentan) • selective (Ambrisentan, Sitaxentan) #WHO-EM. ‡Withdrawn from market. Clinical trials: †Phase III. §Never to phase III M: VAS anat(a:h/u/t/a/l,v:h/u/t/a/l)/phys/devp/cell/prot noco/syva/cong/lyvd/tumr, sysi/epon, injr proc, drug(C2s+n/3/4/5/7/8/9)

v · d · eDrugs used in benign prostatic hypertrophy (G04C) 5α-reductase inhibitors Dutasteride • Finasteride Alpha blockers (α1) Alfuzosin • Doxazosin • Silodosin • Tamsulosin • Terazosin Herbals Pygeum africanum • Serenoa repens Other Mepartricin M: ♂ MRS anat/phys/devp noco/cong/tumr, sysi/epon proc, drug (G3B/4BE/4C)

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Practolol • Primidolol • Procinolol • Pronethalol • Propafenone • Propranolol • Ridazolol • Ronactolol • Soquinolol • Sotalol • Spirendolol • SR 59230A • Sulfinalol • TA-2005 • Talinolol • Tazolol • Teoprolol • Tertatolol • Terthianolol • Tienoxolol • Tilisolol • Timolol • Tiprenolol • Tolamolol • Toliprolol • Tribendilol • Trigevolol • Xibenolol • Xipranolol  Reuptake inhibitors NET Selective norepinephrine reuptake inhibitors: Amedalin • Atomoxetine (Tomoxetine) • Ciclazindol • Daledalin • Esreboxetine • Lortalamine • Mazindol • Nisoxetine • Reboxetine • Talopram • Talsupram • Tandamine • Viloxazine; Norepinephrine-dopamine reuptake inhibitors: Amineptine • Bupropion (Amfebutamone) • Fencamine • Fencamfamine • Lefetamine • Levophacetoperane • LR-5182 • Manifaxine • Methylphenidate • Nomifensine • O-2172 • Radafaxine; Serotonin-norepinephrine reuptake inhibitors: Bicifadine • Desvenlafaxine • Duloxetine • Eclanamine • Levomilnacipran • Milnacipran • Sibutramine • Venlafaxine; 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Iproclozide • Iproniazid • Isocarboxazid • Isoniazid • Linezolid • Mebanazine • Metfendrazine • Nialamide • Octamoxin • Paraxazone • Phenelzine • Pheniprazine • Phenoxypropazine • Pivalylbenzhydrazine • Procarbazine • Safrazine • Tranylcypromine; MAO-A selective: Amiflamine • Bazinaprine • Befloxatone • Befol • Brofaromine • Cimoxatone • Clorgiline • Esuprone • Harmala alkaloids (Harmine, Harmaline, Tetrahydroharmine, Harman, Norharman, etc) • Methylene Blue • Metralindole • Minaprine • Moclobemide • Pirlindole • Sercloremine • Tetrindole • Toloxatone • Tyrima; MAO-B selective: D-Deprenyl • Selegiline (L-Deprenyl) • Ladostigil • Lazabemide • Milacemide • Mofegiline • Pargyline • Rasagiline * Note that MAO-B inhibitors also influence norepinephrine/epinephrine levels since they inhibit the breakdown of their precursor dopamine. COMT Entacapone • Tolcapone  Others Precursors L-Phenylalanine → L-Tyrosine → L-DOPA (Levodopa) → Dopamine • L-DOPS (Droxidopa) Cofactors Ferrous Iron (Fe2+) • S-Adenosyl-L-Methionine • Vitamin B3 (Niacin, Nicotinamide → NADPH) • Vitamin B6 (Pyridoxine, Pyridoxamine, Pyridoxal → Pyridoxal Phosphate) • Vitamin B9 (Folic acid → Tetrahydrofolic acid) • Vitamin C (Ascorbic acid) • Zinc (Zn2+) Others Activity enhancers: BPAP • PPAP; Release blockers: Bethanidine • Bretylium • Guanadrel • Guanazodine • Guanclofine • Guanethidine • Guanoxan; Toxins: Oxidopamine (6-Hydroxydopamine)

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