Health Centres - Hypovase (prazosin)
How does it work?
Hypovase tablets contain the active ingredient prazosin, which is a type of medicine called an alpha-blocker. (NB. Prazosin is also available without a brand name, ie as the generic medicine.) Prazosin has some quite different uses. It works by blocking alpha receptors in certain areas of the body.
Alpha receptors are found on the muscle in the walls of blood vessels. When prazosin blocks these receptors it causes the muscle in the blood vessel to relax and the blood vessel to widen. This lets the blood pass more easily through the blood vessels and hence reduces the pressure in the blood vessels. Prazosin can therefore be used to treat high blood pressure.
Widening the blood vessels also decreases the effort required by the heart to pump blood around the body, because there is less resistance for the heart to pump against. Prazosin can therefore also help treat heart failure, where the pumping action of the heart has become less effective.
Prazosin is also used to treat Raynaud's disease and Raynaud's phenomenon, which are conditions where the arteries supplying blood to the hands and feet go into spasm and narrow. This restricts the blood supply to the fingers and toes and causes them to go pale, cold and painful. Prazosin widens the blood vessels and so increases the blood flow to the hands and feet, thus relieving these symptoms.
Alpha receptors are also found on the muscle in the prostate gland. This gland is found only in men and lies at the top of the tube connecting the bladder to the outside (urethra). The prostate gland often enlarges with advancing age (benign prostatic hyperplasia), pressing on the urethra and obstructing the flow of urine from the bladder. This can cause various urinary symptoms such as difficulty passing urine. By blocking the alpha receptors in the prostate, prazosin causes the muscle to relax. This allows urine to flow freely past the prostate gland and relieves the urinary symptoms of this condition.
What is it used for?
-
High blood pressure .
-
Heart failure.
- Condition called Raynaud's disease or phenomenon, in which the arteries supplying blood to the hands and feet go into spasm, causing pale, cold and painful fingers and toes.
-
Enlarged prostate gland .
Warning!
- Alcohol may enhance the blood pressure lowering effect of this medicine, and this may cause dizziness in some people.
- As this medicine may cause fatigue and dizziness, you should take care when performing potentially hazardous activites, such as driving or operating machinery, until you know how this medicine affects you and are sure you can perform such activities safely.
- Your blood pressure should be monitored regularly during treatment with this medicine.
- In some people with heart failure, this medicine may become less effective over time. If this happens you may notice weight gain or swelling of the legs or ankles. If this occurs you should inform your doctor, as your dose of prazosin or other medicines you are taking may need to be altered.
- If you are scheduled to have eye surgery for cataracts it is important to let your eye specialist know if you are or have been taking this medicine. This is because this type of medicine may make your pupil dilate poorly and the iris (the coloured circular part of the eye) become floppy during the procedure. The specialist needs to know if you have been taking this medicine so they can take appropriate precautions with the medicines and techniques they use during the surgery. You may be asked to stop taking this medicine for a period of time before cataract surgery. Check with your doctor.
Use with caution in
- Elderly people.
- Decreased kidney function.
- Decreased liver function.
- People taking blood pressure lowering medication.
Not to be used in
- Allergy to related medicines (quinazolines), eg doxazosin, terazosin.
- This medicine is not recommended for people who have ever fainted after passing urine (micturition syncope), or who suffer from drops in blood pressure that cause dizziness when moving from a lying down or sitting position to sitting or standing (postural hypotension).
- This medicine is not recommended for people who have heart failure due to a mechanical obstruction of the heart, such as heart valve disease or blood clot in the lung (pulmonary embolism).
- This medicine is not recommended for children under 12 years of age.
This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.
Pregnancy and breastfeeding
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
- This medicine should be used with caution during pregnancy and only if the potential benefit outweighs any potential risk to the developing baby. Seek medical advice from your doctor.
- This medicine may pass into breast milk in small amounts. It should only be used during breastfeeding if the benefit to the mother outweighs any potential risk to the nursing infant. Seek medical advice from your doctor.
Label warnings
- This medication may cause drowsiness. If affected do not drive or operate machinery.
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