PTCB Guide to Antihypertensive Drugs.

Antihypertensive Drugs as a Topic of the PTCB Exam.

Almost half of the US population has elevated blood pressure, or hypertension. Knowing the major antihypertensive drug classes is therefore essential knowledge for practicing pharmacy technicians.

But not all antihypertensive drugs need to be studied. Only the most major drug classes will be tested. In this week’s guide, we cover all major antihypertensive drug classes technicians are required to learn, including:

• Diuretics
• Calcium channel blockers
• ACE inhibitors
• Angiotensin II receptor antagonists
• Beta-blockers
• Alpha-blockers

As with all Top 200 medicines, technicians are only required to learn major indications, side effects, drug interactions and a general idea of the mechanism of action. Try to focus your study in this direction to avoid learning more than is required.

Below, we review the kind of detail and facts that gets tested on the PTCB exam.

Diuretics.

Diuretics are drugs that promote loss of water and electrolytes in urine. By removing excess water and salt from the body, this lowers blood pressure.

There are many kinds of diuretic drug classes. How they differ depends upon which part of the nephron they act – the nephron being the functional unit of the kidney.

• Loop diuretics – furosemide, bumetanide, ethacrynic acid
• Thiazide diuretics – bendroflumethiazide, hydrochlorothiazide, indapamide, chlorthalidone
• Potassium-sparing diuretics – amiloride, spironolactone
• Osmotic diuretics – mannitol

Thiazide-type diuretics are routinely recommended as one of the first-line treatment options for hypertension – either on their own or in combination with other drugs.

One of the disadvantages of loop and thiazide diuretics is that they cause potassium loss, which can lead to hypokalemia. That’s why potassium-sparing drugs, such as amiloride and spironolactone, are advantageous. These diuretics cause diuresis, but do not lower potassium levels. Often, a diuretic – such as furosemide or hydrochlorothiazide – is combined with amiloride, enhancing diuresis while also preventing hypokalemia.

Spironolactone works differently to other diuretics in that it inhibits aldosterone; a hormone that increases water and sodium and potassium retention. Potassium supplements, or drugs that increase potassium levels such as ACE inhibitors, should be avoided with spironolactone and amiloride due to the increased risk of hyperkalemia.

Other side effects of diuretics include:

• Dehydration
• Hypotension
• Increased risk of gout (loop / thiazide diuretics)
• Tinnitus (loop diuretics can cause this effect at high doses). The risk of ototoxicity is increased when loop diuretics are taken with aminoglycoside antibacterial drugs.

Diuretics should be taken in the morning to prevent nocturia (urination at night).

Calcium Channel Blockers.

Calcium channel blockers are routinely prescribed as first-line agents for hypertension.

Key examples:

• Nifedipine
• Amlodipine
• Verapamil
• Diltiazem

Nifedipine and amlodipine are most used for hypertension, whereas verapamil and diltiazem are more commonly used to treat cardiac arrhythmias.

Calcium channel blockers work by preventing the influx of calcium ions into muscle cells of artery walls. This causes arterial relaxation, leading to a marked reduction in blood pressure.

Side effects with calcium channel blockers include:

• Flushing
• Palpitations
• Headache
• Constipation (particularly with verapamil)
• Ankle swelling
• Gingival hyperplasia (gun overgrowth)

Calcium channel blockers should not be taken with beta blockers due to the increased risk of bradycardia (slow heart rate) and heart failure.

Check out our full PTCB guide to calcium channel blockers for more details on this antihypertensive drug class.

ACE Inhibitors.

ACE is an enzyme – the angiotensin-converting enzyme.

By inhibiting this enzyme, ACE inhibitors prevent the conversion of angiotensin I into angiotensin II. Angiotensin II is responsible for releasing the hormone aldosterone into the bloodstream, as well as acting as a vasoconstrictor (constricting veins increases blood pressure).

Along with hypertension, ACE inhibitors are also used to treat chronic heart failure, ischemic heart disease, and diabetic nephropathy.

Examples of ACE inhibitors include:

• Ramipril
• Lisinopril
• Perindopril

Note: ACE inhibitors always end with the suffix – pril.

Side effects with ACE inhibitors include:

• Hypotension (high risk after the first dose. For this reason, patients are counseled to take the first dose before bed)
• Persistent dry cough (due to pulmonary kinin accumulation)
• Elevated potassium levels (hyperkalemia)
• Captopril can cause a metallic-type taste

Because they can cause elevated potassium levels, ACE inhibitors should be avoided with potassium supplements or other drug classes that also increase potassium levels (including potassium-sparing diuretics).

Other risks:

• Taking an NSAID with an ACE inhibitor increases the risk of renal damage.
• ACE inhibitors are teratogenic and should be avoided in pregnancy. Drugs safe for pregnant women with hypertension include nifedipine, methyldopa, labetalol, and hydralazine.

For more on ACE inhibitors, check out our full PTCB guide on this drug class.

Angiotensin II Receptor Blockers.

ACE inhibitors are preferred for treating hypertension, but they can frequently cause a persistent, dry cough. To overcome this side effect, some patients are switched to an angiotensin II receptor blocker.

As we learned, ACE inhibitors prevent conversion of angiotensin I into angiotensin II.

But angiotensin II receptor antagonists block the receptor itself. Remember that angiotensin II promotes aldosterone release and increases vasoconstriction. By blocking the receptor, these two outcomes are prevented.

Examples of angiotensin II receptor blockers (ARBs) include:

• Candesartan
• Irbesartan
• Losartan

Note: angiotensin II receptor blockers always end with the suffix -sartan.

Side effects of ARBs include hypotension, elevated potassium levels, and, in some cases, cough (though much less likely compared to ACE inhibitors!).

As with ACE inhibitors, ARBs should be avoided with potassium supplements or other drug classes that also increase potassium levels.

Beta Blockers.

Beta blockers are medicines widely used in the treatment of a variety of cardiovascular diseases.

However, beta blockers are less commonly used for hypertension i.e. they are not considered a first-line option. Thiazide diuretics and calcium channel blockers are the typical first-line choices. Beta blockers may be used where first-line or second-line options have failed to adequately control the patient’s blood pressure. They may also be used as an add-on to first-line options.

Along with hypertension, beta blockers are also used to treat ischemic heart disease, supraventricular tachycardia, atrial fibrillation, and heart failure. Beta blockers work by reducing the force of contraction and speed of conduction of the heart (typically at beta-1 receptors).

Beta blockers can be readily identified via their shared drug suffix –lol.

Examples include:

• Metoprolol
• Bisoprolol
• Atenolol
• Propranolol

Key warnings:

• Beta blockers are avoided in asthma because they can trigger life-threatening bronchospasm.
• Beta blockers should be avoided with calcium channel blockers due to the risk of bradycardia and heart failure.
• Side effects of beta blockers include vivid dreams and nightmares, cold extremities, impotence (in men), headache, gastrointestinal disturbances, and fatigue.

Alpha Blockers.

As with beta-blockers, alpha blockers are not recommended as first-line therapy.

Instead, they may be used in treatment-resistant hypertension where first-line drugs have proved insufficient in controlling the patient’s hypertension, or in cases where alpha-blockers are used as an add-on treatment to other drugs.

By blocking alpha-1 receptors, these drugs reduce vasoconstriction and therefore reduce blood pressure.

Examples include:

• Doxazosin
• Tamsulosin
• Alfuzosin

Note: alpha blockers may be identified via their common suffix –osin.

Alpha blockers are more commonly used in the treatment of other conditions such as benign prostatic hyperplasia – or an enlarged prostate. Alpha blockers are used to relax smooth muscle of the urinary tract, encouraging the flow of urine.

Side effects of alpha blockers include postural hypotension, dizziness, and a fainting sensation and/or fainting itself. Again, this is more common after the patient takes the first dose of the medicine.

PTCB Sample Exam Questions.

Below you can find five sample PTCB exam questions on the topic of antihypertensive drugs.

These five questions reflect the type of questions that get tested about duplications on the exam – both the style and difficulty. As always, have a go at the questions yourself before comparing your answers with the explanations (in the section below).

Question 1.

Which of these antihypertensive drug causes a persistent dry cough?

a. Losartan

b. Lisinopril

c. Amlodipine

d. Metoprolol

Question 2.

A patient taking spironolactone should be monitored for which electrolyte abnormality?

a. Hypokalemia

b. Hypercalcemia

c. Hyponatremia

d. Hyperkalemia

Question 3.

Which of these antihypertensive drugs must be avoided during pregnancy?

a. Methyldopa

b. Labetalol

c. Enalapril

d. Nifedipine

Correct Answer: C. Enalapril

Question 4.

Which of these drugs works by blocking calcium channels in vascular smooth muscle, leading to vasodilation?

a. Metoprolol

b. Perindopril

c. Furosemide

d. Amlodipine

Question 5.

Which of these antihypertensive drug classes is avoided in asthma due to the risk of bronchospasm?

a. Beta blockers

b. Alpha blockers

c. Thiazide diuretics

d. Angiotensin II receptor blockers

Answer Explanations.

Answer to Question 1 – b. Lisinopril

ACE inhibitors are associated with causing a persistent, dry cough. Examples include ramipril, lisinopril, and perindopril.

Answer to Question 2 – d. Hyperkalemia

Spironolactone is a potassium-sparing diuretic. It therefore increases the risk of potassium accumulation. Patients should be monitored for elevated potassium levels.

Answer to Question 3 – c. Enalapril

Enalapril is an ACE inhibitor. ACE inhibitors are teratogenic and must be avoided during pregnancy. Drugs safe for gestational hypertension include labetalol, nifedipine, hydralazine, and methyldopa.

Answer to Question 4 – d. Amlodipine

Amlodipine is classified as, and works as, a calcium channel blocker. Other CCBs include nifedipine, verapamil, and diltiazem.

Answer to Question 5 – a. Beta blockers

Beta blockers are contraindicated in asthma (particularly cardio-selective drugs) due to the risk of life-threatening bronchospasm.

PTCB Cheat Sheet: Antihypertensive Drugs.

Over the course of today’s guide, you learned:

Major Drug Classes & Examples

• ACE inhibitors: lisinopril, enalapril, ramipril
• ARBs: losartan, valsartan, candesartan
• Beta blockers: metoprolol, atenolol
• Calcium channel blockers (CCBs): amlodipine, nifedipine
• Diuretics: hydrochlorothiazide, furosemide
• Potassium-sparing diuretics: spironolactone, amiloride
• Alpha blockers: doxazosin, terazosin, alfuzosin

Key Mechanisms of Action

• ACE inhibitors → ↓ angiotensin II → ↓ Blood pressure
• ARBs → block angiotensin II receptors
• Beta blockers → ↓ heart rate & cardiac output
• CCBs → vasodilation (↓ peripheral resistance)
• Diuretics → ↓ fluid volume by promoting water/electrolyte loss

High-Yield Side Effects

• ACE inhibitors → dry cough, hyperkalemia, hypotension
• ARBs → hyperkalemia (cough is less likely)
• Beta blockers → bradycardia, fatigue, cold extremities, vivid dreams
• CCBs → gum overgrowth, facial flushing, ankle swelling, constipation
• Diuretics → hypokalemia, hypotension, polyuria, gout attacks
• Spironolactone → hyperkalemia, gynecomastia

Key Warnings

• ACE inhibitors & ARBs → contraindicated in pregnancy
• Beta blockers contraindicated in asthma due to bronchoconstriction

Common Drug Interactions

• ACE inhibitors/ARBs + potassium supplements → hyperkalemia
• Beta blockers + CCBs (e.g. verapamil) → bradycardia/heart block
• Diuretics + Digoxin → toxicity risk (due to low potassium)
• Loop diuretics and aminoglycosides → high risk of ototoxicity

Key Drug Suffixes

• “-pril” = ACE inhibitors
• “-sartan” = Angiotensin II receptor blockers
• “-lol” = Beta blockers
• “-osin” = Alpha blockers
• “-dipine” = Calcium channel blockers

Hope you found this week’s PTCB guide to antihypertensive drugs helpful!

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