Blood pressure medication: an overview of antihypertensive agents

By Cristiano Antonino On Apr 13, 2023

Blood pressure problems, whether pathological or caused by circumstantial situations (pregnancy, for example) are addressed by antihypertensive drugs

Antihypertensives are a class of drugs used in the control of elevated (blood) pressure (hypertension), which is a major cardiovascular risk factor.

Based on their mechanism of action, antihypertensives can be divided into four broad categories:

Drugs acting on the sodium-water balance (diuretics)
Drugs acting on the sympathetic nervous system
Drugs that reduce peripheral resistance (vasodilators)
Drugs active on the renin-angiotensin-aldosterone system

High blood pressure? When to use antihypertensive drugs

Antihypertensives as mentioned are drugs that basically lower blood pressure.

Some of them work by widening blood vessels (vasodilators), others remove excess fluid from the blood or block natural hormones produced by the body that increase blood pressure.

Of course, the doctor takes many factors into account, both in prescription and dosage, such as the age, race, gender of the patient.

Sometimes he or she may find it useful to prescribe a main one to which an additional one or two may be added.

In general, these drugs are taken in pill form, but in the case of hospitalisation it is not uncommon to switch to IV (intravenous) administration.

What do blood pressure medications treat?

Blood pressure medication treats high blood pressure, or hypertension, with the aim of keeping the heart strong and preventing heart failure, heart attack, kidney failure or stroke.

Hypertension makes your heart’s work harder and more demanding.

Lowering your blood pressure makes it easier for your heart to keep pumping blood to essential organs and cells 24 hours a day.

Hypertension, which antihypertensive agents are chosen?

The doctor assesses a number of favourable factors, as well as possible side effects.

The best known and most popular are:

Thiazide
ACE inhibitors.
Calcium channel blockers.

Types of blood pressure medication

A) Adrenergic blockers (including alpha, beta, alpha-beta and peripheral acting blockers)

What they do: they prevent your body from increasing blood pressure in reaction to stress.

Side effects of selected blood pressure medications:

Fainting.
Dizziness.
Fatigue.
Low heart rate.

B) Angiotensin-converting enzyme (ACE) inhibitors

What they do: they prevent your body from producing angiotensin II (a blood vessel constrictor).

Side effects of selected blood pressure medications:

Coughing.
High potassium.
Dizziness.
Angioedema (swelling of the face and neck); if you have this dangerous reaction, you should not take an ACE inhibitor drug again.

C) Angiotensin II receptor blockers (ARBs)

What they do: they prevent angiotensin II from constricting the blood vessels.

Side effects of selected blood pressure medications:

High potassium.
Dizziness.

D) Calcium channel blockers (including dihydropyridines and non-dihydropyridines)

What they do: They keep calcium out of the blood vessels, which allows the blood vessel muscle to relax and loosen.

Side effects of selected blood pressure medications:

Headaches.
Dizziness.
Fast or slow heart rate.
Swelling of the lower leg.

E) Centrally acting alpha-agonists

What they do: they prevent the nervous system from responding to stress.

Side effects of selected blood pressure medications:

Tiredness.
Dry mouth.
Slow heart rate.

F) Direct vasodilators

What they do: They make the blood vessels more open.

Side effects of selected blood pressure drugs:

Fast heart rate.
Headache.
Swelling of the lower leg.

G) Diuretics (including potassium-sparing, loop, and thiazide diuretics)

What they do: they help your blood vessels widen and cause your kidneys to move more fluid and salt into your pee.

Side effects of selected blood pressure medications:

High or low levels of magnesium or potassium.
Stomach upset.
High levels of uric acid.
Dizziness.

What are the risks or complications of antihypertensive drugs?

Some patients experience a sudden drop in blood pressure when they stand up (orthostatic hypotension).

Antihypertensive drugs can make the situation worse and the elderly may feel dizzy and fall, sometimes injuring themselves.

Some antihypertensive drugs alter electrolyte levels as you lose extra fluid in the urine.

Too high or too low levels of potassium can cause dangerous heart rhythms.

Will blood pressure medication lower my heart rate?

Yes, some medicines for high blood pressure, such as beta-blockers, can lower the heart rate.

Which blood pressure medications are safe during pregnancy?

You can take methyldopa, labetalol or nifedipine during pregnancy, but consult your doctor for their recommendation.

Many other antihypertensives are not safe for your developing fetus, so be sure to inform your doctor when you plan to become pregnant.

What is a first-choice medication for hypertension?

First-line (first-choice) options include these names of blood pressure drugs: thiazide diuretics, calcium channel blockers and – for people with kidney disease and heart failure – angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs).

Beta-blockers may also be first-line choices if the patient has a history of heart disease.

Bibliographic references

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Butt DA, Harvey PJ. Benefits and risks of antihypertensive medications in the elderly. (https://pubmed.ncbi.nlm.nih.gov/26497967/) J Intern Med. 2015;278(6):599-626. Accessed 4/29/2022.
CDC. Hypertension. (https://www.cdc.gov/nchs/fastats/hypertension.htm) Accessed 4/29/2022.
Eschenhagen T. Treatment of Hypertension. In: Brunton LL, Hilal-Dandan R, Knollmann BC. Goodman & Gilman’s: The Pharmacological Basis of Therapeutics, 13e. McGraw Hill; 2017. Accessed 4/29/2022.
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Merck Manual Consumer Version. Drug Treatment of High Blood Pressure. (https://www.merckmanuals.com/home/heart-and-blood-vessel-disorders/high-blood-pressure/drug-treatment-of-high-blood-pressure) Accessed 4/29/2022.
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