Drugs for hypertension or high blood pressure: How they work and why you might need them

People with hypertension are at a higher risk for several other health complications such as stroke and heart disease. So, if you have been diagnosed with high blood pressure, it is vital you take you

Anusuya Suresh | Updated: February 5, 2015 4:20 pm

Antihypertensives People with hypertension are at a higher risk for several other health complications such as stroke and heart disease. So, if you have been diagnosed with high blood pressure, it is vital you take your medication as prescribed. Often, people suffer from the wrong notion that taking these medicines daily will make them addicted to it or that it will lead to unpleasant side-effects. While there may be a few side effects with particular drugs, your doctor can always put you on other medication that does not cause such effects. Read on to learn more about anti-hypertensive drugs.

What drugs are used?

Several antihypertensive drugs are available and which one your doctor prescribes will depend on several factors. Diuretics, direct-acting vasodilators, anti-adrenergics, angiotensin converting enzyme (ACE) inhibitors, calcium-channel blockers, direct renin inhibitors and angiotensin receptor blockers are some of the categories of drugs commonly prescribed in hyptertensive patients.

Read more about causes, symptoms, diagnosis and treatment of hypertension.

How do they act?

Antihypertensive drugs act by different mechanisms to achieve the same result – to reduce high blood pressure to normal levels. To be able to understand how these drugs act, let us understand how the body usually regulates blood pressure. Blood pressure depends on three important factors – how fast the heart beats, the amount of blood the heart pumps out at each beat and the width of the arteries through which the blood travels.

Each of these factors can be affected by how your nervous system is functioning and the levels of particular hormones in blood. Blood pressure generally increases if

The brain produces excess of catecholamine hormones or
The kidneys produce too much of angiotensin hormone or
There is an excess of sodium in the blood

Each category of antihypertensive drugs acts by regulating one of these processes to control the increase in blood pressure.

Diuretics: Drain out excess sodium and water from your body.

Anti-adrenergics: Act on either the alpha or beta type of receptors and are accordingly called alpha blockers or beta blockers. Alpha blockers block the action of the nervous system on the blood vessels and this prevents the arteries from growing narrow. Beta blockers reduce the heart rate, slow down the strength of each heart contraction and also inhibit production of angiotensin, leading to a drop in blood pressure.

ACE inhibitors: Prevent formation of angiotensin by inhibiting an important enzyme in the kidney.

Calcium channel blockers: Prevent calcium from entering the muscles in the heart and blood vessels; the heart rate drops and blood vessels stay wide open, so the blood pressure does not rise.

Direct renin inhibitors: Prevent the enzyme renin from catalyzing the reactions that result in formation of angiotensin; lesser angiotensin production means blood pressure stays low.

Angiotensin receptor blockers: Prevent angiotensin from combining with its receptors and so blood pressure stays normal.

How does the doctor decide which drug to give you?

Which drug your doctor prescribes depends on the specific factor that is causing hypertension and it is difficult to state that any one class of drugs is superior to the others.

When you are first diagnosed with mild hypertension, the first line of treatment is to use a diuretic. If this does not give the desired results, the doctor may add a second drug for better results. Combination therapy is sometimes used for hypertension and some drug combinations are available as a single pill. For example, a beta blocker with a diuretic or an ACE inhibitor with a diuretic may be used. Which particular combination your doctor advises depends on whether you have some other health condition.

If you have gout, a diuretic is ruled out because it can aggravate your gout; if you have kidney disease, you may do well with ACE inhibitors, but the doctor will advise you to regularly test levels of potassium that may accumulate and worsen your kidney problems. Diabetic patients are generally prescribed ACE inhibitors or angiotensin receptor blockers. Diuretics are avoided because they may cause a rise in blood sugar levels; beta blockers are also not good because they can hide the condition of blood sugar levels dropping to an unhealthy level.

Quite a few people with hypertension also suffer from high cholesterol levels; in such cases, beta blockers are out of question because they tend to increase levels of triglycerides as well as decrease the ‘good’ HDL cholesterol. Alpha blockers are a better option because they tend to raise HDL cholesterol and also reduce total cholesterol levels. Or a doctor may choose to give you a calcium channel blocker because it does not affect blood lipid levels at all. If you have asthma or chronic bronchitis, your doctor will prescribe any anti-hypertensive other than beta blockers because these can aggravate your existing disease. Patients with coronary artery disease may be given a combination of calcium channel blockers and beta blockers.

Side-effects of anti-hypertensive drugs

Each class of antihypertensive drugs has its own unique drawbacks. Diuretics can cause loss of potassium, frequent urination, fatigue, increased blood sugar levels, gout, muscle cramps and erectile dysfunction in men. Beta blockers can cause respiratory problems to worsen and mask the dangerous decrease of blood sugar in diabetic patients. They may also lead to insomnia and depression. Alpha blockers can cause heart palpitations, headache, nasal congestion, dizziness, dry mouth and a sudden drop in blood pressure when you stand up. Calcium channel blockers are known to cause headaches, edema, constipation and dizziness.

ACE inhibitors cause some people to develop a dry cough or reduce their taste sensations; in some cases, they may also cause potassium levels to go up and therefore, should be used with caution in patients who have kidney problems. The most recent category of angiotensin receptor blocker drugs are free from most of these side effects and this had made them a popular choice in treating patients with hypertension.

Read more about causes, symptoms, diagnosis and treatment of heart disease.

When you are on anti-hypertensive drugs, it is important to remember that the drug you take may interact with other medication you take. Even a simple over the counter painkiller or cough and cold medicine can react with your anti-hypertensive medicine to cause undesirable effects that may or may not be dangerous. Therefore, before you take any other medicine make it a point to ask your doctor about whether it is safe to do so.

With the right medication taken as recommended, it is possible to control your blood pressure. However, make sure you do not miss out on a healthy diet and regular exercise – these are important in deciding how well your body copes with hypertension and can even help you get by with lowest doses of anti-hypertensive medication.

Read more about causes, symptoms, diagnosis and treatment of diabetes.

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Published: May 9, 2013 9:31 am | Updated:February 5, 2015 4:20 pm

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