How does it work?

Zestril tablets contain the active ingredient lisinopril, whichis a type of medicine called an ACE inhibitor. (NB. Lisinopril tablets are alsoavailable without a brand name, ie as thegeneric medicine.)

ACE inhibitors work by blocking the action of a compound in thebody called angiotensin converting enzyme (ACE). Normally ACE produces anothercompound called angiotensin II, as part of the body's natural control of bloodpressure. Angiotensin II causes blood vessels to constrict and narrow, whichincreases the pressure within the blood vessels.

As lisinopril blocks the action of ACE, it reduces theproduction of angiotensin II. This means that the blood vessels are allowed torelax and widen. The overall effect of this is a drop in blood pressure, hencelisinopril can be used to lower high blood pressure.

The reduced pressure within the blood vessels means that theheart doesn't have to work as hard to pump the blood around the body. Thismeans that ACE inhibitors such as lisinopril can also be used to improve thesymptoms of heart failure, where the heart is not pumping as efficiently as itshould be, and to improve survival following a heart attack.

What is it used for?

• High blood pressure (hypertension).
• Heart failure.
• Improving survival following a heart attack.
• Diabetic kidney disease in people with type 2 diabetes and high blood pressure.

Warning!

• Some people may experience dizziness caused by low blood pressure in the first few days of taking this medicine and in particular the first dose. For this reason, the first dose should preferably be taken at bedtime. Your doctor may want you to take the first dose of this medicine under medical supervision in hospital if you are aged over 70 years, have low blood pressure, low levels of fluids or salt in your blood (eg due to dehydration), severe or unstable heart failure, kidney problems, or are taking high doses of diuretic medicines, multiple diuretic medicines, or certain other medicines that dilate your blood vessels.
• If you feel dizzy during treatment this can be relieved by lying down until the symptoms pass. If affected you should avoid performing potentially hazardous tasks such as driving or operating machinary. If you frequently feel dizzy you should let your doctor know, as your dose of this medicine may need reducing.
• Alcohol may enhance the blood pressure lowering effect of this medicine, which can increase dizziness and may increase the risk of fainting.
• ACE inhibitors can sometimes cause an allergic reaction called angioedema. Stop taking this medicine and consult your doctor immediately if you experience difficulty breathing or swallowing, or swelling of your face, lips, tongue, throat, hands, feet or ankles while taking this medicine. This type of allergic reaction has been reported more frequently in people of Afro-Caribbean origin.
• Your blood pressure, kidney function and the amount of potassium in your blood should be regularly monitored while you are taking this medicine.

Use with caution in

• Elderly people.
• Decreased kidney function.
• Narrowing of the arteries that supply blood to the kidneys (renal artery stenosis).
• People with low fluid volume or salt levels in the body, eg due to diuretic therapy, low-sodium diet, diarrhoea or vomiting.
• People taking other medicines for high blood pressure, particularly diuretics (see end of factsheet).
• People with hardening of the arteries (athersclerosis), eg in the heart (cardiovascular disease), brain (cerebrovascular disease) or legs (peripheral vascular disease).
• Low blood pressure (hypotension).
• Severe heart failure.
• Narrowing of the main artery of the body (aortic stenosis).
• Heart disease characterised by thickening of the internal heart muscle and a blockage inside the heart (hypertrophic obstructive cardiomyopathy).
• Enlargement of a chamber of the heart (right ventricle) due to high blood pressure in the pulmonary artery (cor pulmonale).
• Diabetes.
• Diseases affecting connective tissue, eg scleroderma, systemic lupus erythematosus or rheumatoid arthritis (collagen vascular diseases).
• People with kidney failure requiring a certain type of haemodialysis (high-flux membrane).
• People receiving therapy to remove certain types of fat from the blood using a machine (LDL apheresis).
• People undergoing therapy to decrease allergy to bee or wasp stings (desensitisation).

Not to be used in

• Allergy to other ACE inhibitors.
• History of swelling of the lips, face or tongue (angioedema) with no known cause, or caused by previous use of an ACE inhibitor medicine.
• Hereditary angioedema (angioneurotic oedema).
• Pregnancy.
• This medicine is not recommended for children.

This medicine should not be used if you are allergic to one orany of its ingredients. Please inform your doctor or pharmacist if you havepreviously experienced such anallergy.If you feel you haveexperienced an allergic reaction, stop using this medicine and inform yourdoctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy orbreastfeeding. However, other medicines may be safely used in pregnancy orbreastfeeding providing the benefits to the mother outweigh the risks to theunborn baby. Always inform your doctor if you are pregnant or planning apregnancy, before using any medicine.

• This medicine should not be used in pregnancy, particularly in the second and third trimesters, as it may be harmful to the unborn baby. Seek further medical advice from your doctor. If you get pregnant while taking this medicine, stop taking it and consult your doctor immediately. However, in some cases, where this medicine is considered to be life-saving to the mother, treatment may be continued.
• It is not known if this medicine passes into breast milk. It should be used with caution in nursing mothers, and only if the benefits to the mother outweigh any possible risks to the nursing infant. Discuss this with your doctor. The manufacturer states that this medicine is not recommended for use during breastfeeding.

Side effects

Medicines and their possible side effects can affect individualpeople in different ways. The following are some of the side effects that areknown to be associated with this medicine. Just because a side effect is statedhere does not mean that all people using this medicine will experience thator any side effect.

Common (affect between 1 in 10 and 1 in 100 people)

• Dizziness.
• Headache.
• Dry cough.
• Diarrhoea, vomiting.
• Low blood pressure (hypotension).
• Problems with kidney function.

Uncommon (affect between 1 in 100 and 1 in 1000 people)

• Fatigue.
• Feeling of weakness (asthenia).
• Nausea, abdominal pain, indigestion.
• Alteration in taste.
• Rash or itching.
• Changes in mood.
• Difficulty sleeping (insomnia).
• Pins and needles sensations (paraesthesia).
• Awareness of your heartbeat (palpitations).
• Faster than normal heart beat (tachycardia).
• Impotence.
• Increased level of potassium in the blood (hyperkalaemia).

Rare (affect between 1 in 1000 and 1 in 10,000 people)

• Dry mouth.
• Confusion.
• Severe swelling of lips, face, tongue or throat (angioedema - see warning above).
• Hair loss.

Very rare (affect less than 1 in 10,000 people)

• Disturbances in the normal levels of blood cells in the blood (tell you doctor if you get a sore throat, mouth ulcers, high temperature (fever), or feel tired or generally unwell while taking this medicine).
• Inflammation of the pancreas (pancreatitis).
• Problems with liver function, including jaundice or hepatitis (consult your doctor promptly if you develop unexplained itching, yellowing of the skin or eyes, unusually dark urine, nausea and vomiting, abdominal pains, loss of appetite or flu-like symptoms while taking this medicine).
• Severe allergic skin reactions.

The side effects listed above may not include all of the sideeffects reported by the medicine'smanufacturer.For moreinformation about any other possible risks associated with this medicine,please read the information provided with the medicine or consult your doctoror pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicinesyou are already taking, including those bought without a prescription andherbal medicines, before you start treatment with this medicine. Similarly,check with your doctor or pharmacist before taking any new medicines whiletaking this one, to ensure that thecombination is safe.

Lisinopril has an additive effect with other medicines thatdecrease blood pressure, particularly other medicines used to treat high bloodpressure (antihypertensives). In people taking antihypertensive medicines itmay cause a large drop in blood pressure with the first dose, particularly inpeople taking diuretic medicines such as furosemide. This may cause dizziness,which can usually be relieved by lying down until the symptoms pass. If you aretaking a diuretic medicine, your doctor may reduce your dose or ask you to stoptaking it for a few days before starting lisinopril. This is to prevent yourblood pressure from dropping too low. If you frequently 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 bloodpressure include the following:

• other ACE inhibitors, eg enalapril
• aldesleukin
• alpha-blockers such as prazosin
• alprostadil
• angiotensin II receptor antagonists such as losartan
• antipsychotics
• benzodiazepines, eg temazepam, diazepam
• baclofen
• beta-blockers such as propranolol
• calcium-channel blockers such as verapamil, nifedipine
• clonidine
• diazoxide
• diuretics, eg furosemide, bendroflumethiazide
• dopamine agonists, eg bromocriptine, apomorphine
• hydralazine
• levodopa
• MAOI antidepressants, eg phenelzine
• methyldopa
• minoxidil
• moxonidine
• moxisylyte
• nicorandil
• nitrates, eg glyceryl trinitrate
• tizanidine.

Non-steroidal anti-inflammatory drugs (NSAIDs, eg indometacin,aspirin, diclofenac, ibuprofen) may reduce the blood pressure lowering effect oflisinopril, and may increase the risk of a decline in kidney function.You should avoid taking this type of painkiller unless recommended by your doctor.

There may be a risk of raised potassium levels in the blood(hyperkalaemia) if any of the following medicines are taken with lisinopril,hence these are not normally recommended for use in combination withlisinopril. If you are taking any of the following with this medicine youshould have regular blood tests to monitor the amount of potassium in yourblood:

• angiotensin II receptor antagonists, eg losartan
• ciclosporin
• drospirenone
• epoetin (this may also oppose the blood pressure lowering effect of lisinopril)
• heparin
• potassium-containing salt substitutes (eg Lo-Salt)
• potassium salts, eg potassium citrate for cystitis
• potassium-sparing diuretics (eg spironolactone, triamterene, amiloride)
• potassium supplements.

Lisinopril may increase the blood level of the medicine lithiumand for this reason, it is not normally recommended for people taking lithium.People taking this medicine in combination with lithium should have the levelof lithium in their blood closely monitored.

Lisinopril may possibly enhance the blood sugar lowering effectof insulin and oral antidiabetic medicines, and so could increase the risk oflow blood sugar (hypoglycaemia). People with diabetes should thereforecarefully monitor their blood sugar while taking this medicine, particularly inthe first few weeks of treatment.

There may be an increased risk of a drop in the normal numbersof white blood cells in the blood if this medicine is taken in combination withany of the following medicines:

• allopurinol
• azathioprine
• immunosuppressant therapy
• procainamide.

If you are taking any of these in combination with thismedicine, you should have regular blood tests to monitor the levels of yourblood cells, particularly if you also have any kidney problems or diseasesaffecting connective tissue, eg scleroderma, systemic lupus erythematosus or rheumatoid arthritis(collagen vascular diseases). Tell your doctor if you experience any signs ofinfection, such as fever, sore throat or mouth ulcers, as these could be signsof problems with your white blood cells.

Other medicines containing the same active ingredient

Lisinopril tablets are also available without a brand name, ieas thegeneric medicine.