How does it work?
Apresoline tablets contain the active ingredient hydralazine, which is a type of medicine known as a vasodilator. Hydralazine is also available without a brand name, ie as the generic medicine.
Hydralazine acts through an unknown mechanism to relax and widen the small arteries of the body (arterioles). This reduces the pressure inside the blood vessels and hence lowers high blood pressure.
Hydralazine must be used with other medicines in the treatment of high blood pressure, for two reasons. Firstly, the body's natural response to widening of the arterioles and a drop in blood pressure is to increase the heart rate, which would then increase the blood pressure again. As this is an unwanted effect when treating high blood pressure, a beta-blocker, such as propranolol, is often included in the treatment to slow the reflex increase in heart rate.
Secondly, hydralazine can cause fluid and salt retention, which increases the volume of fluid and therefore the pressure within the blood vessels. As this is also not beneficial in treating high blood pressure, a diuretic, such as furosemide, may be included in treatment to remove this excess fluid.
By lowering the blood pressure in the arteries, hydralazine also reduces the effort required by the heart to pump blood around the body. This means it can be used in heart failure, where the pumping mechanism of the heart is less effective.
What is it used for?
- Moderate to severe high blood pressure (hypertension) (in combination with other medicines such as beta-blockers and diuretics).
- Moderate to severe congestive heart failure (in combination with long-acting nitrates such as isosorbide mononitrate, when other treatment has been ineffective).
- Hydralazine is not licensed for use in children, however it may sometimes be used by specialists on an unlicensed basis to treat high blood pressure in children.
How do I take it?
- Apresoline tablets can be taken either with or without food. The tablets should be swallowed with a drink of water.
- The dose prescribed and how often the medicine needs to be taken depends on the condition being treated. For the treatment of high blood pressure, Apresoline tablets are usually taken twice a day. For the treatment of heart failure the tablets are usually taken three to four times a day. It is important to follow the instructions given by your doctor. These will be printed on the dispensing label your pharmacist has put on the packet of medicine.
- If you forget to take a dose take it as soon as you remember, unless it is nearly time for your next dose. In this case leave out the missed dose and just take your next dose as usual. Do not take a double dose to make up for a missed dose.
- This medicine may reduce your ability to drive or operate machinery safely. Do not drive or operate machinery until you know how this medicine affects you and you are sure it won't affect your performance.
- If you drink alcohol while taking this medicine this could make you feel dizzy or faint.
- If this medicine is taken in doses higher than 100mg daily for longer than six months it can sometimes cause a syndrome similar to a condition called systemic lupus erythematosus. Your doctor may want you to have a blood and urine test every six months while you are taking this medicine to help check for this problem. You should tell your doctor if you get any of the following symptoms while taking this medicine, as they could be early signs of a problem and the medicine may need to be stopped: pain or inflammation in the joints, fever, rash, shortness of breath or unexplained weight loss.
- This medicine may rarely decrease the number of blood cells in your blood. A low white blood cell count can increase your susceptibility to infections; a low red blood cell count causes anaemia and a low platelet count can cause problems with blood clotting. For this reason, you should tell your doctor immediately if you experience any of the following symptoms during your treatment, as they may indicate problems with your blood cells: unexplained bruising or bleeding, purple spots, black or tarry stools, sore mouth or throat, mouth ulcers, high temperature (fever) or other signs of infection, or suddenly feeling tired, breathless, or generally unwell. Your doctor may need to take a blood test to check your blood cells.
- If you need to have any surgery or other procedure where you will be given an anaesthestic, it is important that you tell the doctor, dentist or anaesthetist that you are taking this medicine.
- If you are taking this medicine to treat heart failure you should not stop taking it suddenly, unless on the advice of a doctor, because this is likely to make your heart failure get worse. If treatment with this medicine is stopped this should usually be done gradually, following the instructions given by your doctor.
Use with caution in
- People with coronary artery disease, eg angina pectoris.
- People who have recently had a heart attack.
- People with disease of the blood vessels in and around the brain (cerebrovascular disease).
- Decreased kidney function.
- Decreased liver function.
- People whose liver has a reduced ability to metabolise certain medicines (slow acetylator status).
Not to be used in
- People with a long-term autoimmune disease affecting connective tissue called systemic lupus erythematosus (SLE), or related diseases, eg scleroderma.
- People with decreased heart function in combination with a very fast heart rate, for example due to an overactive thyroid gland.
- People with obstructive conditions of the heart that make it difficult for the heart to pump blood, for example narrowing of the main artery leaving the heart (aortic stenosis), narrowing of one of the valves of the heart (mitral valve stenosis) or inflammation around the heart (constrictive pericarditis).
- People with right-sided heart failure caused by high blood pressure in the pulmonary artery, through which blood is pumped to the lungs (cor pulmonale).
- Hereditary blood disorders called porphyrias.
This medicine should not be used if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.
If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
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.
- The manufacturer states that this medicine should be avoided in the first and second trimesters of pregnancy. It may be used with caution in the third trimester if there is no safer alternative, or if it is needed to treat pre-eclampsia or eclampsia. Seek further medical advice from your doctor.
- The medicine passes into breast milk. At normal doses this is not known to have any harmful effects on a nursing infant, however the baby should be monitored for possible side effects. Ask your doctor for further advice.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
Very common (affect more than 1 in 10 people)
- Faster than normal heartbeat (tachycardia).
- Awareness of your heartbeat (palpitations).
Common side effects (affect between 1 in 10 and 1 in 100 people)
- Low blood pressure (hypotension).
- Chest pain (angina).
- Pain in the joints or muscles.
- Swelling of the joints.
- Disturbances of the gut such as diarrhoea, constipation, nausea, vomiting or abdominal pain.
- Systemic lupus erythematosus-like syndrome (see warning section above).
Rare (affect between 1 in 100 and 1 in 100,000 people)
- Loss of appetite.
- Weight loss.
- Blocked nose.
- Watery eyes.
- Eye inflammation (conjunctivitis).
- Swelling due to excess fluid retention (oedema).
- Inability of the heart to pump blood efficiently (heart failure).
- Blood or protein in the urine.
- Problems with the liver.
- Decreased numbers of white blood cells, red blood cells or platelets in the blood (see warning section above).
- Anxiety or agitation.
- Shortness of breath.
- Feeling generally unwell.
- Kidney failure.
- Difficulty passing urine.
- Nerve problems. Tell your doctor if you notice any pins and needles, tingling or numb sensations while you are taking this medicine.
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.
For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
How can this medicine affect other medicines?
It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to make sure that the combination is safe.
Hydralazine is likely to have an additive effect with other medicines that decrease blood pressure, particularly medicines that are used to treat high blood pressure (antihypertensives). This may cause dizziness, which can usually be relieved by lying down until the symptoms pass. If you feel dizzy while taking this medicine in combination with other medicines that can lower blood pressure you should let your doctor know, as your doses may need adjusting. Other medicines that decrease blood pressure include the following:
- ACE inhibitors, eg enalapril
- alpha-blockers such as prazosin
- angiotensin II receptor antagonists such as losartan
- antipsychotics such as chlorpromazine
- benzodiazepines, eg temazepam, diazepam
- beta-blockers such as propranolol
- calcium-channel blockers such as verapamil, nifedipine
- diazoxide (should not be used in combination with hydralazine)
- diuretics, eg furosemide, bendroflumethiazide
- dopamine agonists, eg bromocriptine, apomorphine
- MAOI antidepressants, eg phenelzine
- nitrates, eg glyceryl trinitrate
The following medicines may reduce the blood pressure lowering effect of this medicine:
- corticosteroids, such as dexamethasone or prednisolone
- oestrogens, such as those in the contraceptive pill
- regular use of non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, diclofenac or indomethacin (occasional painkilling doses are unlikely to have a significant effect).
Other medicines containing the same active ingredient
Hydralazine tablets are available without a brand name, ie as the generic medicine.
Hydralazine is also available as an injection (Apresoline injection). This is used to treat hypertensive emergencies, particularly those associated with pregnancy (pre-eclampsia).