Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD
GENERIC NAME: doxazosin mesylate
BRAND NAME: Cardura
DRUG CLASS AND MECHANISM: Doxazosin is an oral drug used for treating
high
blood pressure and symptoms of benign prostatic hyperplasia (BPH, a noncancerous
enlargement of the prostate gland). It belongs to a class of drugs called
alpha-1 adrenergic blockers. Other drugs in this class include alfuzosin
(Uroxatral), terazosin (Hytrin), tamsulosin (Flomax), silodosin (Rapaflo), and
prazosin (Minipress). Doxazosin prevents norepinephrine that is released by
nerves from binding to alpha-1 receptors on smooth muscle surrounding blood
vessels and in the prostate and bladder. By blocking the effect of
norepinephrine, doxazosin relaxes the smooth muscle. Relaxation of the smooth
muscle surrounding blood vessels causes them to enlarge (dilate) and thereby
reduces blood pressure. Relaxation of smooth muscle in the prostate and bladder
improves the flow of urine and reduces the pain and discomfort characteristic of
BPH. The FDA approved doxazosin in November 1990.
PRESCRIPTION: Yes
GENERIC AVAILABLE: Yes
PREPARATIONS: Tablets: 1, 2, 4, and 8 mg. Tablets (Extended Release): 4, 8 mg
STORAGE: Doxazosin should be stored at room temperature, 15-30 C (59-86 F).
PRESCRIBED FOR: Doxazosin is used for the treatment of hypertension (high
blood pressure) and benign prostatic hyperplasia (BPH).
DOSING: The recommended dose of doxazosin for hypertension is 1-16 mg daily.
The recommended dose for benign prostatic hyperplasia is 1-8 mg daily.
DRUG INTERACTIONS: Vardenafil (Levitra) or tadalafil (Cialis) and doxazosin
have additive blood pressure lowering effects. Combining vardenafil or tadalafil
(Cialis) with doxazosin may cause excessive blood pressure reduction.
PREGNANCY: There are no adequate studies of doxazosin in
pregnant women.
NURSING MOTHERS: There are no adequate studies of doxazosin in
nursing
mothers.
SIDE EFFECTS: Common reactions include
dizziness, fatigue, headache,
shortness of breath, diarrhea, abdominal pain, edema (fluid accumulation) and
low blood pressure. Doxazosin causes significant reduction in blood pressure
after administration of the first dose (first dose effect). This reduction in
blood pressure may be associated with dizziness and fainting, especially when
rising from a sitting position. To avoid this, patients should rise slowly from
a sitting position, start treatment with the 1 mg dose, and then doses should be
adjusted upwards slowly. Priapism (painful, prolonged penile erection) and a
reduction in white blood cells have been associated with doxazosin.
Last Editorial Review: 2/20/2009
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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