Prazolok 2

Indications

Prazosin is used to treat high blood pressure and to relieve urinary symptoms caused by an enlarged prostate (benign prostatic hyperplasia), such as a weak stream and needing to pass urine often. It is also sometimes used for Raynaud's phenomenon (fingers turning white or blue in the cold) and, less often today, for heart failure.

How It Works

It is an alpha blocker. It relaxes the muscle in the walls of blood vessels, which lowers blood pressure, and relaxes the muscle around the prostate and bladder neck, which makes it easier to pass urine.

Dosage and Administration

The first dose can cause a sudden drop in blood pressure, so treatment starts low: usually 0.5 mg at bedtime, then 0.5 mg two or three times a day for several days, increased slowly by the doctor. High blood pressure: the usual maintenance dose is a few mg a day in divided doses, up to a maximum of 20 mg a day. Enlarged prostate: often 0.5 mg twice a day to start, usually up to 2 mg twice a day. If you stop for more than a few days, ask the doctor before restarting, as you may need to start again at the low dose.

Interactions

• Other blood pressure medicines, diuretics, beta blockers (such as Atenolol) and alcohol can cause a large drop in blood pressure, especially at the start.
• Sildenafil, Tadalafil and similar medicines can cause dizziness or fainting; take only as advised by the doctor.
• Pain killers such as Ibuprofen can reduce its effect on blood pressure.

Contraindications

• Allergy to prazosin or related medicines (such as Doxazosin or Terazosin).
• A history of fainting while passing urine.
• Heart failure caused by a blockage, such as narrowing of the aortic valve.

Side Effects

Common: dizziness (especially when standing up), headache, drowsiness, weakness, palpitations, nausea, a stuffy nose and swollen ankles.

Get urgent medical help for:

• Fainting or near-fainting.
• Chest pain or a fast, pounding heartbeat that does not settle.
• A painful erection lasting more than 4 hours.
• Swelling of the face or throat, difficulty breathing or a severe rash.

Pregnancy and Lactation

Use in pregnancy only if the doctor decides it is needed. Small amounts pass into breast milk; the doctor will decide whether it is suitable while breastfeeding.

Precautions and Warnings

• Take the first dose at bedtime. If you feel dizzy, sit or lie down, and get up slowly.
• Do not drive or use machines until you know how it affects you, especially after the first dose or a dose increase.
• Tell the eye surgeon before cataract surgery, as it can affect the iris during the operation.
• Use with care in liver or kidney disease and in older people.

Overdose

Can cause very low blood pressure, drowsiness and fainting. Lie the person flat with legs raised and get emergency medical help.

Therapeutic Class

Alpha-1 adrenergic blocker.

Storage

Store below 30°C in a dry place, away from light and out of the reach of children.