Summary This article discusses short points for the most common drugs used for hypertension. These drugs include the diuretics, the ACE Inhibitors, the Calcium Channel Blockers, and the Beta-Blockers.

Diuretics

1. Thiazides

Hydrochlorothiazide (HCTZ)

MOA: Increases the Sodium and water excretion in the distal convoluted tubules. This results in a decrease in the extracellular volume, decreased preload, decreased cardiac out, and decreased renal blood flow.
Contraindications: Not used for patients with inadequate kidney function (rather use loop diuretics), liver failure, gout, pregnant patients, diabetic patients
Side Effects: ↓ Potassium, ↑Uric acid, ↑Glucose (Diabetogenic), ↑Cholesterol, Sexual dysfunction in males

2. Loop diuretics

Furosemide or “Lasix”

Commonly used in patients who fail on thiazides or for severe hypertension with oedema due to congestive cardiac failure or renal insufficiency
MOA: Acts on the Na-K-2Cl cotransporter on the loop of Henle to inhibit the reabsorption of Na, K, and Cl. They also increase the production of prostaglandins which causes vasodilation (this improves flow to the kidneys and decreases vascular resistance)
Contraindications: ? NSAIDS (add more)
Side Effects: ↓Potassium, ↑Uric acid, ↓Sodium, Dehydration, Postural Hypotension

3. Potassium Sparing (Mineralocorticoid Receptor Antagonist)

Spironolactone

MOA: This is an aldosterone receptor antagonist which reduces the amount of Potassium lost in the urine. This drug is commonly used in combination with other diuretics that tend to lower the Potassium level (since Spironolactone prevents this loss)
Side Effects: ↑Potassium, Gastric upset

4. Osmotic Diuretics

Mannitol

MOA: Inhibits the reabsorption of water and sodium in the proximal convoluted tubule and in the descending loop of Henle. This is due to the drug’s osmotic effects, it opposes the actions of antidiuretic hormone (ADH).

ACE Inhibitors

Enalapril

MOA: This drug blocks the enzyme (Angiotensin Converting Enzyme: ACE), which converts Angiotensin-I (ANG-I) into Angiotensin-II (ANG-II). By doing this, it results in the following:
- Vasodilation (blocks the effect of ANG-II, which is a potent vasoconstrictor)
- ↑Na an water excretion (because it blocks the effects of ANG-II, which wont be able to stimulate the release of Aldosterone)
- ↑Increases venous capacity
- ↑Increases the accumulation of bradykinin (this occurs because ACE is responsible for breaking down bradykinin. Accumulation of bradykinin results in a renal blood vessel vasoconstriction and also accumulation results in a dry cough for the patient)
Contraindications: Pregnancy (Fetotoxic), history of angioedema, depending on renal failure (GFR <30, K more than 6), Renal artery stenosis
Side Effects: Angioedema, Postural hypotension, dry cough (if this cough occurs, you may change it to ARB)

Angiotensin-II Receptor Blocker

Losartan

MOA: This drug blocks the angiotensin receptors. This results in arteriolar and venous dilation. This would also prevent the release of aldosterone. This drug does not increase the levels of bradykinin (therefore no cough or angioedema).
Side Effects: Similar to ACE Inhibitors but without the cough/angioedema

Renin Inhibitors

Aliskiren

MOA: Inhibits the effects of renin, this blocks the RAAS system at that level and hence results in vasodilation and other effects which end up lowering the blood pressure.

Calcium Channel Blockers

Verapamil, Diltiazem, and Amlodipine

This includes 3 groups, which include the following agents: Verapamil, Diltiazem, and Amlodipine.

- MOA: ↓Calcium influx into the muscle cells, resulting in decreased contractility, and increased relaxation of the muscles. This results in vasodilation and decreased contraction force of the heart.
- Side Effects: Pedal edema, light headedness

Beta-Blockers

Atenolol, Propranolol, Carvedilol

Receptor locations: B1 Receptors (found in the heart, kidneys), B2 Receptors (found in the lungs, GIT, liver, uterus, vascular smooth muscle, skeletal muscle), B3 Receptors (fat cells)
Types: Cardio-Selective B1 (Atenolol), Non-Selective (Propranolol, Timolol), and Alpha-Beta blocker (Labetalol, Carvedilol)
MOI: Decreases the blood pressure via several mechanisms: Decreased cardiac output, decreased sympathetic outflow from the CNS, inhibit renin release
Contraindications: Asthma (remember B agonists are used for treating asthma), COPD, Diabetes (masks the symptoms of hypoglycemia such as tachycardia, sweating, palpitations), patients with sinus bradycardia/AV block
Side Effects: Bradycardia, Bronchospasms, Sexual dysfunction, heart failure and hypotension, fatigue, insomnia

Alpha-Blockers

Prazosin, Doxazosin

MOA: Decreases the peripheral vascular resistance (smooth muscle relaxation of the arterioles) and causes venous smooth muscle relaxation. Some of the agents are also used to treat problems with the prostate.

Alpha-Beta Blockers

Labetalol, Carvedilol

These agents block the alpha and beta receptors. Have the effects of the agents mentioned above.

Other Agents

Centrally acting agents (Alpha-Methyldopa), Arterial Dilators (Hydralazine), Potassium Channel Openers (Minoxidil), Vasodilators (Nitrates)

References and Further Reading 1. Whalen, K. (2019) Lippincott Illustrated Reviews Pharmacology. Wolters Kluwer.

Published on 13 June 2022

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Common Drugs used for hypertension