Doxazosin

What is Doxazosin?

• Doxazosin (Cardura; Cardura XL) is an alpha1 adrenergic antagonist used in the therapy of hypertension and benign prostatic hypertrophy.
• Cardura XL is not indicated for the treatment of hypertension.

Doxazosin

What are the uses of this medicine?

Doxazosin (Cardura; Cardura XL) tablets are used to treat:

• the symptoms of benign prostatic hyperplasia (BPH)
• high blood pressure (hypertension)

Doxazosin ball-and-stick

Limitations of use:

• Cardura XL is not indicated for the treatment of hypertension.

How does this medicine work?

• The mesylate salt form of doxazosin, a quinazoline compound with smooth muscle relaxing activity.
• Doxazosin mesylate selectively antagonizes alpha-1-adrenergic receptors in smooth muscle of the bladder neck and prostate, thereby relaxing the smooth muscle and decreasing the obstruction and urethral resistance seen with benign prostate hyperplasia (BPH).
• This may improve BPH symptoms.
• This agent also blocks alpha-1-adrenergic receptors in peripheral vascular smooth muscle, which leads to vasodilatation and a subsequent decrease in peripheral vascular resistance.

Who Should Not Use this medicine ?

This medicine have cannot be used in patients who:

• are allergic to doxazosin, other quinazolines, or any of the ingredients in doxazosin tablets.

What drug interactions can this medicine cause?

• Tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take.

Be sure to mention any of the following:

• other medicine for high blood pressure or medicine to treat erectile dysfunction (ED) called a phosphodiesterase type 5 (PDE-5) inhibitor. The use of doxazosin tablets with PDE-5 inhibitors can lead to a drop in blood pressure or to fainting.
• antihistamines
• clarithromycin (Biaxin, in Prevpac)
• ipratropium (Atrovent, in Combivent)
• itraconazole (Onmel, Sporanox)
• ketoconazole (Nizoral)
• medications for erectile dysfunction (ED) such as sildenafil (Revatio, Viagra), tadalafil (Adcirca, Cialis), or vardenafil (Levitra, Staxyn)
• medications for high blood pressure
• medications for HIV/AIDS including atazanavir (Reyataz), indinavir (Crixivan), nelfinavir (Viracept), ritonavir (Norvir, in Kaletra), or saquinavir (Invirase)
• medications for irritable bowel disease, motion sickness, Parkinson's disease, ulcers, or urinary problems
• nefazodone
• telithromycin(Ketek)
• voriconazole (Vfend)

Is this medicine FDA approved?

• Doxazosin was approved for use in the United States in 1990, and currently more than 5 million prescriptions are filled yearly.
• Doxazosin is still used for treatment of hypertension, although rarely as a first line agent and usually in combination with other antihypertensive drugs.

How should this medicine be used?

Recommended dosage:

Benign Prostatic Hyperplasia:

• The recommended initial dosage of doxazosin tablets is 1 mg given once daily either in the morning or evening.
• The dose may be titrated at 1 to 2 week intervals to 2 mg, and thereafter to 4 mg and 8 mg once daily.
• The maximum recommended dose for BPH is 8 mg once daily.
• Routinely monitor blood pressure in these patients.

Hypertension:

• The initial dosage of doxazosin tablets is 1 mg given once daily.
• Daily dosage may be doubled up 16 mg once daily, as needed, to achieve the desired reduction in blood pressure.

Administration:

• Doxazosin comes as a tablet and an extended-release tablet to take by mouth.
• Take doxazosin tablets exactly as your healthcare provider tells you to take them.
• Your healthcare provider will tell you how many doxazosin tablets to take and when to take them.
• Your healthcare provider may need to change your dose of doxazosin tablets until it is the right dose for you.
• Doxazosin extended-release tablet is usually taken once a day with breakfast.
• Swallow the extended-release tablets whole; do not split, chew, or crush them.
• Your doctor will start you on a low dose of doxazosin and gradually increase your dose, not more than once every 1 to 2 weeks.

What are the dosage forms and brand names of this medicine?

This medicine is available in fallowing doasage form:

• As a tablet and an extended-release tablet

This medicine is available in fallowing brand namesː

• Cardura; Cardura XL

What side effects can this medication cause?

The most common side effects of this medicine include:

• fatigue
• malaise
• hypotension
• dizziness
• weakness or lack of energy (asthenia)

Doxazosin tablets may cause serious side effects, including:

• A sudden drop in blood pressure
• Eye problems during cataract surgery
• A painful erection that will not go away

The most common side effects of CARDURA XL include:

• tiredness
• headache
• low blood pressure
• dizziness

CARDURA XL may cause serious side effects including:

• postural hypotension
• intraoperative floppy iris syndrome
• blockage of the digestive tract
• prolonged erection of the penis

What special precautions should I follow?

• Do not drive or perform any hazardous task until at least 24 hours after you have taken doxazosin tablets.
• Postural hypotension with or without symptoms (e.g., dizziness) may develop within a few hours following administration of doxazosin mesylate. Advise patient how to avoid symptoms resulting from postural hypotension and what measures to take should they develop.
• Concomitant administration of doxazosin mesylate with a PDE-5 inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension.
• Intraoperative Floppy Iris Syndrome (IFIS) has been observed during cataract surgery in some patients on or previously treated with alpha1 blockers.
• Carcinoma of the prostate causes many of the symptoms associated with BPH and the two disorders frequently co-exist. Carcinoma of the prostate should therefore be ruled out prior to commencing therapy with doxazosin mesylate for the treatment of BPH.
• Alpha1 antagonists, including doxazosin, have been associated with priapism (painful penile erection, sustained for hours and unrelieved by sexual intercourse or masturbation). This condition can lead to permanent impotence if not promptly treated.
• There is limited information on the presence of doxazosin mesylate in human milk.
• Doxazosin is associated with a low rate of transient serum aminotransferase elevations, but has not been linked to instances of clinically apparent acute liver injury.

What to do in case of emergency/overdose?

Symptoms of overdosage may include:

• hypotension
• drowsy
• epilepsy
• depression
• grand mal seizure

Management of overdosage:

• In case of overdose, call the poison control helpline of your country. In the United States, call 1-800-222-1222.

• Overdose related information is also available online at poisonhelp.org/help.
• In the event that the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services. In the United States, call 911.
• The most likely manifestation of overdosage would be hypotension, for which the usual treatment would be intravenous infusion of fluid.
• As doxazosin is highly protein bound, dialysis would not be indicated.

Can this medicine be used in pregnancy?

• It is not known if doxazosin tablets will harm your unborn baby.

Can this medicine be used in children?

• The safety and effectiveness of doxazosin mesylate has not been established in children.

What are the active and inactive ingredients in this medicine?

Doxazosin tablets:

• Active ingredient: doxazosin mesylate
• Inactive ingredients: lactose monohydrate, magnesium stearate, microcrystalline cellulose, pregelatinized corn starch, sodium lauryl sulfate, and sodium starch glycolate.

CARDURA XL:

• Active Ingredient: doxazosin
• Inactive Ingredients: polyethylene oxide, sodium chloride, hypromellose, red ferric oxide, titanium dioxide, magnesium stearate, cellulose acetate, Macrogol®, pharmaceutical glaze, and black iron oxide.

Who manufactures and distributes this medicine?

Doxazosin tablets: Manufactured In India By:

• Piramal Pharma Limited, Plot No. 67-70, Sector 2, Pithampur, Dist. Dhar, Madhya Pradesh, India

Manufactured For:

• Teva Pharmaceuticals USA, Inc., Parsippany, NJ

CARDURA XL:

• Roerig
• Division of Pfizer inc.

What should I know about storage and disposal of this medication?

Doxazosin tablets:

• Store at 20° to 25°C (68° to 77°F).
• Dispense in a well-closed container.

CARDURA XL:

• Store CARDURA XL at 59°F to 86°F (15°C to 30°C).
• Keep CARDURA XL and all medicines out of reach of children.

• Dailymed label info on Doxazosin
• FDA Doxazosin

Doxazosin Resources
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