Difficulty: Intermediate | Prerequisites: Autonomic nervous system basics, diuretics study notes
Beyond diuretics, the main antihypertensive classes work by relaxing blood vessels, slowing the heart, or blocking hormones that raise blood pressure. Calcium channel blockers relax vascular smooth muscle, ACE inhibitors and ARBs target the renin-angiotensin-aldosterone system, beta blockers reduce heart rate and contractility, and vasodilators directly relax arterial walls. The nursing thread running through all of them is monitoring for hypotension, knowing when to hold a dose, and watching for class-specific side effects.
Calcium channel blocker (CCB)
A drug that blocks L-type calcium channels in vascular smooth muscle and cardiac tissue, causing vasodilation and (for some agents) reduced heart rate. In simple terms, it relaxes blood vessels and, depending on the drug, can also slow the heart.
Dihydropyridine
A subclass of CCBs (nifedipine, amlodipine) that primarily dilates peripheral blood vessels with minimal effect on the heart. Think of these as the "vascular" CCBs.
Non-dihydropyridine
A subclass of CCBs (verapamil, diltiazem) that affects both blood vessels and the heart, reducing heart rate and contractility. Think of these as the "cardiac" CCBs.
ACE inhibitor
A drug that blocks angiotensin-converting enzyme, preventing the conversion of angiotensin I to angiotensin II. In simple terms, it stops the body from making a hormone that tightens blood vessels and retains salt.
ARB (angiotensin II receptor blocker)
A drug that blocks the receptor where angiotensin II acts, producing similar effects to ACE inhibitors but without the dry cough. Think of it as the alternative when a patient cannot tolerate ACE inhibitors.
First-dose hypotension
A significant drop in blood pressure after the first dose of an ACE inhibitor (or an alpha blocker). In simple terms, the first pill can drop blood pressure more dramatically than expected.
Beta blocker
A drug that blocks beta-adrenergic receptors to reduce heart rate, contractility, and blood pressure. Think of it as a drug that tells the heart to slow down and work less hard.
Selective beta blocker
A beta blocker that primarily targets beta-1 receptors in the heart (e.g. metoprolol, atenolol). In simple terms, it focuses on the heart and is safer for patients with asthma or diabetes.
Nonselective beta blocker
A beta blocker that blocks both beta-1 (heart) and beta-2 (lungs, blood vessels) receptors (e.g. propranolol). In simple terms, it affects the heart and the lungs, which is why it can trigger bronchospasm.
Vasodilator
A drug that directly relaxes smooth muscle in blood vessel walls, lowering blood pressure by widening arteries. In simple terms, it opens up the pipes so blood flows with less resistance.
Tags: nifedipine, Procardia, amlodipine, Norvasc, verapamil, Calan, diltiazem, Cardizem, dihydropyridine, non-dihydropyridine, grapefruit interaction
Block calcium from entering smooth muscle cells of blood vessels and cardiac cells
Vasodilation lowers blood pressure
Non-dihydropyridines also decrease heart rate and contractility
Dihydropyridines (vascular focus): nifedipine (Procardia), amlodipine (Norvasc)
Non-dihydropyridines (cardiac + vascular): verapamil (Calan), diltiazem (Cardizem)
Hypertension
Angina (stable and vasospastic)
Verapamil and diltiazem: atrial dysrhythmias, rate control
Peripheral oedema (especially ankles)
Flushing, headache
Dizziness
Reflex tachycardia (the body compensates for vasodilation by speeding up the heart)
Hypotension
Bradycardia (because they slow the heart)
Constipation (especially verapamil)
Hypotension
Heart failure exacerbation (due to reduced contractility)
AV block
Grapefruit juice inhibits the CYP3A4 enzyme in the gut, which normally breaks down CCBs. Drinking grapefruit juice increases the drug level in the blood, intensifying effects and side effects. Patients should avoid grapefruit juice while taking any CCB, but the interaction is particularly significant with nifedipine, verapamil, and diltiazem.
Monitor blood pressure and heart rate before administering
Hold verapamil or diltiazem if heart rate is below 60 bpm
Assess for peripheral oedema, especially with dihydropyridines
Teach patients to avoid grapefruit juice
Monitor for constipation with verapamil; encourage fibre and fluids
Do not crush or chew extended-release formulations
Assess for drug interactions: verapamil and diltiazem should not be given with beta blockers due to additive bradycardia and heart block risk
Tags: lisinopril, Zestril, enalapril, Vasotec, captopril, Capoten, ramipril, benazepril, ACE inhibitor, angiotensin-converting enzyme, dry cough, first-dose hypotension, pril drugs
Block the enzyme that converts angiotensin I to angiotensin II
Without angiotensin II, blood vessels dilate and aldosterone secretion decreases
The result is lower blood pressure, reduced sodium and water retention, and reduced cardiac workload
Also prevent the breakdown of bradykinin, which contributes to vasodilation but also causes the hallmark dry cough
All end in "-pril":
Captopril (Capoten) – short-acting, taken 2 to 3 times daily, must be taken on an empty stomach
Enalapril (Vasotec) – can be taken once or twice daily
Lisinopril (Zestril, Prinivil) – taken once daily, one of the most commonly prescribed
Ramipril (Altace) – once daily
Benazepril (Lotensin) – once or twice daily
Most ACE inhibitors are taken once daily (lisinopril, ramipril)
Captopril is the exception: taken two to three times daily on an empty stomach (food reduces absorption by 30 to 40%)
Enalapril and benazepril may be dosed once or twice daily
Dry, persistent, nonproductive cough (caused by bradykinin accumulation; occurs in up to 20% of patients)
Hypotension, especially first-dose hypotension
Hyperkalemia (because aldosterone is suppressed, so potassium is retained)
Angioedema (swelling of the face, lips, tongue, throat; a medical emergency)
Dizziness, headache
Teratogenic: contraindicated in pregnancy (can cause foetal renal damage and death)
The first dose of an ACE inhibitor can cause a dramatic drop in blood pressure, especially in patients who are volume-depleted or on diuretics. To minimise risk, the first dose is often given at bedtime, and diuretics may be held for a day or two before starting.
Switch to an ARB. ARBs block angiotensin II at the receptor level and do not affect bradykinin, so they do not cause the cough.
Check blood pressure (baseline)
Check serum potassium
Assess renal function (BUN, creatinine)
Check for pregnancy
Ensure the patient is not taking potassium supplements or potassium-sparing diuretics without provider awareness
Monitor blood pressure closely, especially after the first dose
Monitor serum potassium (risk of hyperkalemia)
Monitor renal function
Teach patients to report swelling of the face, lips, or tongue immediately (angioedema)
Educate about the dry cough; reassure that it is a known side effect and not harmful, but report it
Advise against use of potassium supplements or salt substitutes unless directed
Contraindicated in pregnancy: educate women of childbearing age
Captopril: take on an empty stomach
Tags: losartan, Cozaar, valsartan, Diovan, irbesartan, Avapro, candesartan, sartan drugs, angiotensin receptor
Block angiotensin II at its receptor (AT1 receptor) on blood vessels and the adrenal cortex
Produce vasodilation and decreased aldosterone secretion, similar to ACE inhibitors
Do not affect bradykinin, so they do not cause the dry cough seen with ACE inhibitors
All end in "-sartan":
Losartan (Cozaar)
Valsartan (Diovan)
Irbesartan (Avapro)
Candesartan (Atacand)
ARBs can raise serum potassium levels because they reduce aldosterone secretion, just like ACE inhibitors. Monitor potassium closely, especially when combined with potassium-sparing diuretics or potassium supplements.
Hyperkalemia
Hypotension, dizziness
Teratogenic: contraindicated in pregnancy (same as ACE inhibitors)
Angioedema (rare, but possible)
Monitor blood pressure
Monitor serum potassium and renal function
Contraindicated in pregnancy
ARBs are the go-to alternative when a patient develops a dry cough on ACE inhibitors
Advise patients to avoid potassium supplements and salt substitutes unless directed by the provider
Tags: metoprolol, Lopressor, Toprol-XL, atenolol, Tenormin, propranolol, Inderal, carvedilol, Coreg, labetalol, beta-1, beta-2, selective, nonselective, cardioselective
Before studying beta blockers, recall the autonomic nervous system basics:
Sympathetic nervous system ("fight or flight"): increases heart rate, dilates bronchi, raises blood pressure, dilates pupils, inhibits digestion
Parasympathetic nervous system ("rest and digest"): slows heart rate, constricts bronchi, increases digestion
Beta blockers oppose sympathetic stimulation at beta receptors
Beta-1 (B1) receptors: found primarily in the heart. Stimulation increases heart rate, contractility, and conduction velocity.
Beta-2 (B2) receptors: found in the lungs (bronchial smooth muscle) and blood vessels. Stimulation causes bronchodilation and vasodilation.
Block beta-adrenergic receptors, reducing the effects of sympathetic stimulation
At B1 receptors: decrease heart rate, decrease contractility, decrease conduction through the AV node, and reduce renin release from the kidneys
The net effect is lower blood pressure, reduced cardiac workload, and decreased myocardial oxygen demand
Selective (B1 only, "cardioselective"):
Metoprolol (Lopressor, Toprol-XL)
Atenolol (Tenormin)
Acebutolol
Nonselective (B1 + B2):
Propranolol (Inderal)
Nadolol (Corgard)
Timolol
Combined alpha and beta blockers:
Carvedilol (Coreg)
Labetalol (Trandate)
Memory aid: drugs ending in "-olol" are beta blockers.
Selective beta blockers (metoprolol, atenolol) block only B1, so they affect the heart without significantly affecting the lungs. Safer for patients with asthma or COPD.
Nonselective beta blockers (propranolol) block both B1 and B2. Blocking B2 in the lungs can cause bronchoconstriction, making them dangerous for patients with asthma, COPD, or reactive airway disease.
Hypertension
Heart failure (carvedilol, metoprolol succinate)
Angina
Dysrhythmias
Migraine prophylaxis (propranolol)
Post-myocardial infarction (to reduce mortality)
Glaucoma (timolol, as eye drops)
Bronchospasm (B2 blockade in the lungs)
Bradycardia, heart block
Hypotension
Fatigue, depression, insomnia
Cold extremities (reduced peripheral circulation)
Hypoglycemia masking: beta blockers suppress tachycardia and tremor, which are the body's early warning signs of low blood sugar. Diabetic patients on beta blockers may not recognise hypoglycemia until it is severe.
Health conditions that make nonselective beta blockers problematic:
Asthma or COPD (risk of bronchospasm)
Diabetes (masking of hypoglycemic symptoms)
Peripheral vascular disease (worsened circulation)
Heart block or severe bradycardia
Heart rate below 60 bpm
Systolic blood pressure below 100 mmHg
Signs of heart failure worsening (new or worsening oedema, weight gain, crackles)
Always notify the provider when holding a dose
Beta blockers mask the sympathetic signs of hypoglycemia: tachycardia, palpitations, tremor, and diaphoresis. Teach diabetic patients to monitor blood glucose frequently rather than relying on these physical cues.
Never stop beta blockers abruptly; taper gradually to avoid rebound hypertension, tachycardia, or angina
Rise slowly to avoid orthostatic hypotension
Monitor pulse daily; report a resting heart rate below 60
Report dizziness, excessive fatigue, or weight gain
Diabetic patients: monitor blood glucose more frequently
Tags: clonidine, Catapres, methyldopa, Aldomet, central-acting, alpha-2 agonist, pregnancy hypertension
Clonidine (Catapres)
Methyldopa (Aldomet)
Both act centrally (in the brain) to reduce sympathetic outflow, resulting in decreased heart rate and blood pressure.
Methyldopa is the preferred drug for treating hypertension during pregnancy. It has the longest track record of safety for both the mother and the foetus.
Drowsiness, sedation
Dry mouth
Rebound hypertension if stopped abruptly (this is a major safety concern; must taper)
Constipation
Bradycardia
Depression
Never discontinue abruptly; taper over several days to prevent rebound hypertension
Available as oral tablets, transdermal patch (changed weekly), or injection
Apply transdermal patch to a hairless area of the upper arm or torso; rotate sites
Monitor blood pressure and heart rate
Teach patients that drowsiness and dry mouth are common; these often diminish over time
Caution with alcohol and other CNS depressants (additive sedation)
Tags: hydralazine, Apresoline, minoxidil, Loniten, sodium nitroprusside, Nipride, direct vasodilator, hypertensive crisis
Directly relax smooth muscle in arteriolar walls, causing vasodilation
Lower blood pressure by reducing peripheral vascular resistance
Do not act through the nervous system or hormones; the effect is directly on the vessel
Hydralazine (Apresoline): arteriolar dilator, used for hypertension and heart failure; also used in pregnancy
Minoxidil (Loniten): a potent arteriolar dilator reserved for severe hypertension; topical form (Rogaine) is used for hair growth
Sodium nitroprusside (Nipride): dilates both arteries and veins; used IV for hypertensive emergencies
Hirsutism (excessive hair growth, which led to its use as a topical hair growth treatment)
Reflex tachycardia
Fluid retention, oedema
Pericardial effusion (rare but serious)
Given IV only, in an ICU or closely monitored setting
Wrap the IV bag in foil or an opaque cover because the drug is light-sensitive and degrades when exposed to light
Monitor blood pressure continuously (arterial line often used)
Can cause cyanide toxicity with prolonged use (metabolised to cyanide); monitor for metabolic acidosis, confusion, and air hunger
The antidote for cyanide toxicity is sodium thiosulfate or hydroxocobalamin
Check blood pressure and heart rate before administration
Hold and notify the provider if blood pressure is below the set parameter (commonly systolic below 100 mmHg)
Teach patients about orthostatic hypotension: rise slowly from sitting or lying
Encourage adherence; many patients stop taking antihypertensives because they feel fine
Monitor for dizziness, falls risk (especially in older adults)
Teach patients not to stop medications abruptly
Review all current medications for interactions (especially other antihypertensives, which can compound hypotension)
Students often think all CCBs slow the heart. Only the non-dihydropyridines (verapamil, diltiazem) do. Dihydropyridines (nifedipine, amlodipine) can actually cause reflex tachycardia.
Many students assume the dry cough from ACE inhibitors means the drug is not working. The cough is caused by bradykinin accumulation and is unrelated to efficacy. The solution is to switch to an ARB.
Students sometimes mix up selective and nonselective beta blockers. Selective (metoprolol) targets the heart. Nonselective (propranolol) hits both heart and lungs. The lungs are where the danger lies for asthma patients.
A common error is thinking beta blockers can be stopped at any time. Abrupt discontinuation causes rebound tachycardia, hypertension, and can precipitate angina or MI.
⚠️ The grapefruit interaction with CCBs is a classic exam question. Know that it increases drug levels.
⚠️ ACE inhibitor dry cough and the switch to an ARB is one of the most frequently tested nursing pharmacology concepts.
⚠️ First-dose hypotension with ACE inhibitors: know how to minimise risk (give at bedtime, hold diuretics).
⚠️ Know the parameters for holding beta blockers: HR below 60, SBP below 100.
⚠️ Beta blockers mask hypoglycemia: this comes up repeatedly in exam questions involving diabetic patients.
⚠️ Never stop clonidine or beta blockers abruptly. Both cause dangerous rebound effects.
⚠️ Methyldopa is the go-to antihypertensive in pregnancy.
⚠️ Sodium nitroprusside must be wrapped in foil (light-sensitive) and can cause cyanide toxicity.
True or False: Amlodipine causes bradycardia.
False. Amlodipine is a dihydropyridine CCB that can cause reflex tachycardia, not bradycardia.
Fill in the blank: ACE inhibitors end in the suffix ______.
-pril.
True or False: ARBs cause a dry cough similar to ACE inhibitors.
False. ARBs do not affect bradykinin and do not cause the cough.
Fill in the blank: A nurse should hold a beta blocker if the heart rate is below ______ bpm.
True or False: Clonidine can be discontinued abruptly without risk.
False. Abrupt discontinuation causes rebound hypertension.
Q: A patient on verapamil reports eating grapefruit every morning. What should the nurse teach?
A: Grapefruit juice inhibits CYP3A4, increasing verapamil levels in the blood and raising the risk of bradycardia, hypotension, and heart block. The patient should avoid grapefruit juice and whole grapefruit while on this medication.
Q: A patient with asthma is prescribed propranolol. What concern should the nurse raise with the provider?
A: Propranolol is a nonselective beta blocker that blocks B2 receptors in the lungs, which can cause bronchospasm. A cardioselective (B1-selective) beta blocker such as metoprolol would be safer.
Q: A patient on lisinopril has a serum potassium of 5.8 mEq/L. What is the nurse's priority action?
A: Hold the lisinopril and notify the provider immediately. A potassium of 5.8 is dangerously elevated (hyperkalemia) and ACE inhibitors raise potassium further. The patient needs urgent evaluation and likely potassium-lowering treatment.
Q: A patient taking enalapril develops swelling of the lips and tongue. What is the nurse's priority?
A: This is angioedema, a medical emergency. The nurse should hold the medication, ensure airway patency, prepare for emergency intervention (epinephrine, airway management), and notify the provider immediately. Enalapril should be permanently discontinued.
Q: A diabetic patient on metoprolol says they feel fine and have had no episodes of low blood sugar. Should the nurse be reassured?
A: Not necessarily. Beta blockers mask the early sympathetic signs of hypoglycemia (tachycardia, tremor, diaphoresis). The patient may experience hypoglycemia without recognising it. Teach the patient to monitor blood glucose regularly rather than relying on physical symptoms.
Q: A patient on clonidine says they ran out of medication three days ago. What should the nurse assess for?
A: Rebound hypertension. Abrupt discontinuation of clonidine can cause a dangerous spike in blood pressure, along with tachycardia, headache, and anxiety. The nurse should check blood pressure immediately and notify the provider.
This material connects directly to diuretics (which are often co-prescribed with these drugs and create electrolyte interactions), cardiac glycosides (digoxin toxicity risk increases with the potassium changes caused by ACE inhibitors and diuretics), and the autonomic nervous system (which is the foundation for understanding beta blockers and anti-adrenergic drugs). Vasodilators and ACE inhibitors also connect to heart failure management.
Calcium channel blockers, CCB, nifedipine, amlodipine, verapamil, diltiazem, dihydropyridine, non-dihydropyridine, ACE inhibitors, lisinopril, enalapril, captopril, ramipril, angiotensin-converting enzyme, ARBs, losartan, valsartan, irbesartan, angiotensin receptor blocker, beta blockers, metoprolol, atenolol, propranolol, carvedilol, labetalol, selective, nonselective, cardioselective, B1, B2, clonidine, methyldopa, central-acting, alpha-2 agonist, hydralazine, minoxidil, sodium nitroprusside, vasodilator, antihypertensive, first-dose hypotension, dry cough, bradykinin, grapefruit interaction, rebound hypertension, bronchospasm, hypoglycemia masking, nursing pharmacology, cardiovascular drugs