Author: Dr Arun Mahtani Editor: Dr B V Baliga
CAPTOPRIL, RAMIPRIL, ENALAPRIL, LISINOPRIL, PERINDOPRIL
- What are ACE Inhibitors?
- ACE Inhibitors is a short form for “Angiotensin Converting Enzyme” Inhibitors. This is a group of drugs that is used in the treatment of numerous conditions such as high blood pressure (i.e hypertension), Heart Failure, and heart attack (i.e Myocardial Infarction).
- How do ACE inhibitors act?
- Angiotensin Converting Enzyme (ACE) is an enzyme present in the lungs. This helps in conversion of a compound Angiotensin 1 (AT1) to Angiotensin 2 (AT2).
Angiotensin 2 has various effects on the body which include the following:
1) It causes narrowing of the blood vessels which increases the blood pressure.
2) It causes release of a hormone which is called as the ‘anti diuretic hormone’ (ADH). This hormone increases the water absorbing capacity of the kidneys and is responsible for fluid accumulation in the body.
The more the water absorbed, more is the amount of fluid in the blood vessels. This increased amount of fluid can raise the volume of blood in the body, leading to an increase in blood pressure.
3) It stimulates the sympathetic nervous system (a group of nerve fibres) which causes narrowing of blood vessels.
4) It also stimulates the release of another hormone called ‘aldosterone’ from the adrenal glands which increases salt and water retention by the kidneys, thus increasing blood pressure.
ACE Inhibitors abolishes all these effects by not allowing AT1 to get converted to AT2. In brief, ACE inhibitors –
- Causes relaxation of blood vessels, thus reducing the pressure within it.
- Decreases the work that the heart must do to pump blood through the body. In other words, it reduces the stress on the heart (this effect is beneficial in heart failure).
- Decreases salt and water retention by the kidneys.
- What are the clinical uses of ACE inhibitors?
- 1) Treatment of high blood pressure (Hypertension): Once you start taking ACE inhibitors blood pressure comes down swiftly.
2) Treatment of heart failure: ACE inhibitors decrease workload on the heart by causing relaxation of blood vessels and decreasing salt and water retention from the kidneys. Hence, the force required to eject blood from the heart decreases.
3) Treatment of heart attacks – By reducing the stress the heart undergoes when pumping blood, ACE inhibitors can relax the heart muscle.
4) Diabetic Kidney Disease (Diabetic Nephropathy): ACE inhibitors reduce pressure within the kidney, allowing the kidney to function normally. In essence it protects the kidney in patients with diabetes.
5) Other conditions – ACE inhibitors can help manage patients who have long standing kidney disease, conditions such as scleroderma and migraine as well.
- How do I take ACE inhibitors?
- Generally your doctor will start you on a low dose to see if you are coping well with the drug as well as to check if your blood pressure comes under control. Some patients may experience dizziness after taking the first dose, which is why it may be prescribed to be taken at night.
If the blood pressure response is inadequate, the doctor may increase the dose as required. ACE inhibitors can be taken with food or after food.
- How long do I need to stay on treatment?
- Length of treatment is usually indefinite unless you experience an adverse effect with the drug. The requirement for treatment will be reviewed with each medical consultation with your doctor.
- Do I need to undergo any tests if I am on ACE inhibitors?
- A blood test is usually done before starting ACE Inhibitors and about 1-2 weeks after the first dose. These tests check the function of your kidney.
For patients with hypertension a blood test is done every 6 months to a year. For patients with heart failure the test is carried out more often around once every 3-6 months. This duration may change depending on the condition of the patient.
- Are there any side effects?
- As is the case with any drug, ACE inhibitors have certain side effects (which are rare). The side effects include
- Cough – A persistent dry cough usually is experienced by 1 in 10 patients within few weeks of starting therapy. The development of this side effect is not related to the dose the patient is taking. The cough disappears after the drug is stopped (this can take up to a week). Patients will require alternative medicine in the place of ACE inhibitors in such scenarios.
- Allergic reactions – These are rare but have been described in clinical practice. Some patients may develop swelling of lips and tongue and difficulty swallowing a short time after taking the first dose. This is called angioedema and must be treated immediately. If you notice any such symptoms, it is important to speak to your doctor or go to a hospital immediately.
- Altered kidney function – In a small number of patients, ACE inhibitors can increase creatinine levels in the body.
- Elevated potassium levels – This requires urgent treatment.
- Low blood pressure (hypotension) – Those who are on ACE inhibitors for the first time might experience dizziness, hence it is advised to stay at home for at least a period of four hours after taking your first dose of ACE inhibitors.
If you feel dizzy, sitting down or lying down should ease the problem. If you still continue to feel dizzy, do consult your doctor.
Please note that ACE inhibitors will only be prescribed if the benefits of taking the drug are greater than the risks. In fact, ACE inhibitors are perfectly safe drugs, and studies have shown ACE inhibitors to be one of the best drugs in treating high blood pressure and heart disease.
- Who should avoid ACE inhibitors?
- 1) Pregnant Women: If you are pregnant already or are expected to become pregnant, discontinue the use of ACE Inhibitors as it can harm the growing fetus. We recommend you speak to your doctor first before doing so.
2) Patients having bilateral renal artery stenosis as ACE Inhibitors can cause kidney failure in these patients. Renal artery stenosis is a condition where the arteries that are supplying both the kidneys are narrowed. Patients require some form of treatment before they are started back on therapy.
- Are there any drug interactions?
- ACE Inhibitors should not be given along with the following drugs
- Potassium Supplements
- Potassium Sparing Diuretics such as Spironolactone.
- NSAIDS such as Brufen and diclofenac
These interactions are rare and are rarely life threatening.