Cozaar (losartan)

How does it work?

Cozaar tablets contain the active ingredient losartan potassium, which is a type of medicine called an angiotensin II antagonist. It works by preventing the action of a hormone in the body called angiotensin II.

Angiotensin II normally acts on special receptors in the body Vogirax, with two main results. Firstly, it causes the peripheral blood vessels to narrow, and secondly, it stimulates the production of another hormone called aldosterone. Aldosterone causes salt and water to be retained by the kidneys, which increases the volume of fluid in the blood vessels.

Losartan blocks the receptors that angiotensin II acts on, and so prevents its actions. The main result of this is that the peripheral blood vessels are allowed to widen, which means that there is more space and less resistance in these blood vessels. This is the main mechanism by which the pressure in the blood vessels is lowered.

Blocking the actions of angiotensin II also reduces the action of aldosterone on the kidneys. The result of this is an increase in the amount of fluid removed from the blood by the kidneys. This decreases the amount of fluid in the blood vessels, which also lessens the resistance and pressure in the blood vessels.

The combined overall effect of these changes is to lower the blood pressure, hence losartan is used to treat high blood pressure.

Losartan has been shown to reduce the risk of stroke in people who have high blood pressure together with an enlargement in the left side of their heart (left ventricular hypertrophy). People with both these conditions may therefore be prescribed losartan to reduce their chances of experiencing a stroke. However, this medicine is not effective for this particular use in black patients.

Losartan has also been shown to delay the progression of kidney disease in people with type 2 diabetes who have related kidney complications. If you have diabetic kidney disease you may be prescribed losartan for this reason, regardless of whether or not you also have high blood pressure.

What is it used for?

• High blood pressure (hypertension)
• Reducing risk of stroke in people with high blood pressure and an enlarged heart (left ventricular hypertrophy)
• Delaying progression of kidney disease in people with type 2 diabetes and kidney complications (diabetic nephropathy/macroalbuminuria).

Warning!

• Dizziness and weariness may occasionally occur during treatment with blood pressure lowering medicines. This may be made worse by drinking alcohol. If you are affected, caution is required when driving or operating machinery.
• You should have regular blood tests to monitor the amount of potassium in your blood while you are taking this medicine, particularly if you are elderly or have any problems with your kidneys.

Use with caution in

• Elderly people over 75 years of age
• Decreased fluid volume in the body, eg due to diuretic therapy, low salt diet, kidney dialysis, diarrhoea, vomiting, dehydration
• History of decreased liver function
• Moderate to severely decreased kidney function
• Narrowing of the artery which supplies blood to the kidneys (renal artery stenosis)
• People who have had a kidney transplant
• Severe heart failure
• Heart disease characterised by thickening of the internal heart muscle and a blockage inside the heart (hypertrophic obstructive cardiomyopathy)
• Narrowing of one of the valves in the heart (mitral valve stenosis)
• Narrowing of the main artery of the body (aortic stenosis)
• History of swelling of the lips, face or tongue (angioedema) caused by an ACE inhibitor or other medicine.

Not to be used in

• Pregnancy
• Breastfeeding.

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.

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.

• This medicine should not be used during pregnancy as it may be harmful to the developing foetus. You should use adequate contraception to avoid getting pregnant while taking this medicine. Seek medical advice from your doctor. If you get pregnant during treatment you should stop taking this medicine immediately and consult your doctor.
• It is not known whether this medicine passes into breast milk. Breastfeeding mothers should either stop treatment during the time that they are breastfeeding, or not breastfeed and continue treatment. This will depend on how important the medicine is for the mother's health. Seek medical advice from your doctor.

Side effects

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. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

• Dizziness
• Weakness or loss of strength (asthenia)
• Fatigue
• Balance problems involving the inner ear (vertigo)
• Low blood pressure (hypotension)
• High blood potassium level (hyperkalaemia)
• Diarrhoea
• Low red blood cell count (anaemia) or platelet count (thrombocytopenia)
• Inflammation of the liver (hepatitis)
• Alteration in results of liver function tests
• Migraine
• Pain in the muscles and joints
• Rash or itching
• Cough
• Severe swelling of lips, face or tongue (angioedema)

The side effects listed above may not include all of the side effects reported by the drug'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 ensure that thecombination is safe.

If you are already taking a high dose of a diuretic medicine, eg furosemide, your doctor may need to reduce its dose before you start this medicine, to avoid causing a large drop in blood pressure that might result in dizziness or fainting.

Losartan may increase the amount of potassium in your blood. If this medicine is taken with other medicines that can increase blood potassium, this effect may be enhanced. Such medicines include the following and these should generally be avoided while you are taking losartan:

• non-steroidal anti-inflammatory drugs, eg indometacin, diclofenac, ibuprofen
• potassium-sparing diuretics (eg spironolactone, triamterene, amiloride)
• potassium supplements
• potassium containing salt substitutes.

Losartan may increase blood levels of the medicine lithium. If you are taking lithium and start treatment with losartan, you should let your doctor know if you experience any signs that your lithium level is increasing, for example: loss of appetite, diarrhoea, vomiting, blurred vision, muscle weakness, lack of co-ordination, drowsiness, tremor, unsteadiness, muscle twitching, ringing in the ears or confusion. Your doctor will need to check your lithium level.

Non-steroidal anti-inflammatory drugs (NSAIDs), eg indometacin, diclofenac, ibuprofen, may oppose the blood pressure lowering effect of losartan and may increase the risk of side effects on the kidneys.

Rifampicin may reduce the blood level and effect of losartan.

Other medicines containing the same active ingredient

There are currently no other medicines available in the UK that contain losartan as the sole active ingredient.

Cozaar-comp contains losartan in combination with the diuretic hydrochlorothiazide.