Antihypertensive Agents: Generic and Brand Names
- Angiotensin-Converting Enzymes (ACE) Inhibitors
- benazepril (Lotensin)
- captopril (Capoten)
- enalapril (Vasotec IV)
- quinapril (Accupril)
- Angiotensin II-Receptor Blockers (ARBs)
- irbesartan (Avapro)
- losartan (Cozaar)
- telmisartan (Micardis)
- valsartan (Diovan)
- Calcium-Channel Blockers
- amlodipine (Norvasc)
- diltiazem (Diltiazem)
- nicardipine (Cardene)
- nifedipine (Adalat, Procardia)
- verapamil (Calan, Isoptin)
- Vasodilators
- hydralazine (Apresoline)
- minoxidil (Loniten)
- nitroprusside (Nitropress)
- Renin Inhibitors
- aliskiren (Tekturna)
Disease Spotlight: Hypertension
Hypertension affects nearly half of U.S. adults, about 48% (roughly 120 million people), under the 2017 ACC/AHA threshold of 130/80 mm Hg (CDC).
About 90% of cases have no known cause and are called essential hypertension, marked by elevated total peripheral resistance. Organs are still perfused effectively and patients usually have no symptoms, which is why hypertension is the "silent killer." Secondary hypertension is elevated blood pressure from a known cause; for example, a pheochromocytoma (tumor of the adrenal medulla) releases high catecholamines that drive pressure up sharply.
In 2017, the American College of Cardiology and the American Heart Association revised their hypertension guidelines, lowering the threshold that defines hypertension from 140/90 mm Hg to 130/80 mm Hg (2017 ACC/AHA guideline). Under the current categories: normal is less than 120 mmHg systolic and less than 80 mmHg diastolic; elevated is 120 to 129 mmHg systolic with less than 80 mmHg diastolic; stage 1 hypertension is a systolic of 130 to 139 mmHg or a diastolic of 80 to 89 mmHg; stage 2 hypertension is a systolic at or above 140 mmHg or a diastolic at or above 90 mmHg.
ACE Inhibitors
ACE inhibitors act in the lungs to block conversion of angiotensin I into angiotensin II, a potent vasoconstrictor.
Therapeutic Action
By blocking angiotensin II (a potent vasoconstrictor and stimulator of aldosterone release), they lower blood pressure with a loss of serum sodium and fluid and a slight rise in serum potassium.
Indications
Primarily for hypertension, alone or combined with other drugs. Combined with diuretics and digoxin, they treat heart failure and left ventricular dysfunction by cutting peripheral resistance and blood volume, which lowers cardiac workload. They are also approved for diabetic nephropathy, where decreased stimulation of renal angiotensin receptors is thought to slow damage to the renal artery.
By age group: safety and efficacy are not established in children; ACE inhibitors are not allowed in pregnancy; older adults are more prone to toxicity from conditions affecting metabolism and excretion, so monitor renal and hepatic function.
Pharmacokinetics
| Route | Onset | Peak |
|---|---|---|
| Oral | 15 min | 30-90 min |
| Half-life (T1/2) | Metabolism | Excretion |
|---|---|---|
| 2 h | liver | kidney (urine) |
Contraindications and Cautions
Allergy to ACE inhibitors. Renal impairment, which the drugs' decreased renal blood flow can worsen. Heart failure, which their hemodynamic changes can worsen. Hyponatremia and hypovolemia, which the drug's effects can worsen. Pregnancy and lactation, for potential fetal harm and decreased milk production; pregnant women should use barrier contraceptives while taking the drug.
Adverse Effects
GI: irritation, ulcer, constipation, liver injury. GU: renal insufficiency, renal failure, proteinuria. CV: reflex tachycardia, chest pain, heart failure, cardiac arrhythmias. EENT: rash, alopecia, dermatitis, photosensitivity. Captopril is associated with sometimes-fatal pancytopenia, cough, and GI distress.
Interactions
Allopurinol increases the risk of hypersensitivity. NSAIDs increase the risk of reduced antihypertensive effect.
Nursing Considerations
Assess for the contraindications above (renal impairment, hyponatremia, hypovolemia). Get baseline weight, vital signs, skin condition, and labs (renal and hepatic function, serum electrolytes, CBC with differential). Relevant nursing diagnoses include decreased cardiac output related to fluid volume excretion, impaired skin integrity, and increased infection risk from the drug's effect on circulating blood cells.
Teach lifestyle changes (regular exercise, weight loss, smoking cessation, low-sodium diet). Give on an empty stomach, one hour before or two hours after a meal, for optimal absorption. Monitor renal and hepatic function tests to catch developing failure and signal a dose reduction. Watch for signs of fluid volume loss (diarrhea, vomiting, dehydration) to prevent excessive hypotension. Teach the patient and family the drug's effects and what to report. Evaluate through blood pressure monitoring, watching for adverse effects (hypotension, arrhythmias, renal failure, cough, pancytopenia), confirming understanding, and monitoring compliance.
Angiotensin II-Receptor Blockers
ARBs block vasoconstriction and aldosterone release by selectively blocking angiotensin II receptors in vascular smooth muscle and the adrenal cortex.
Therapeutic Action
They block the blood-pressure-raising effect of the renin-angiotensin-aldosterone system (RAAS).
Indications
Like ACE inhibitors, used alone or combined with other agents for hypertension. Used in heart failure for patients who do not respond to ACE inhibitors. By blocking angiotensin receptors in the vascular endothelium, they slow renal disease progression in patients with type 2 diabetes and hypertension.
By age group: safety and efficacy are not established in children; ARBs are not allowed in pregnancy; older adults are more prone to toxicity, so monitor renal and hepatic function.
Pharmacokinetics
| Route | Onset | Peak | Duration |
|---|---|---|---|
| Oral | Varies | 1-3 h | 24 h |
| Half-life (T1/2) | Metabolism | Excretion |
|---|---|---|
| 2 h | liver | urine and feces |
Contraindications and Cautions
Allergy to ARBs. Renal and hepatic impairment, which can alter metabolism and excretion and raise toxicity risk. Hypovolemia, worsened by blocking compensatory mechanisms. Pregnancy and lactation, for potential fetal harm and possible pregnancy termination in the second and third trimester; it is unknown whether ARBs enter breast milk, but they are generally avoided in lactating women.
Adverse Effects
CNS: headache, dizziness, syncope, weakness. Respiratory: upper respiratory infection symptoms, cough. GI: diarrhea, abdominal pain, nausea, dry mouth, tooth pain. EENT: rash, alopecia, dry skin.
Interactions
Phenobarbital, indomethacin, and rifamycin cause loss of ARB effectiveness. Ketoconazole, fluconazole, and diltiazem decrease the antihypertensive effect.
Nursing Considerations
Assess for the contraindications above (drug allergy, hypovolemia, renal impairment). Get baseline weight, vital signs, skin condition, and labs (renal and hepatic function, serum electrolytes). Relevant nursing diagnoses include ineffective tissue perfusion from the drug's fluid excretory effect, impaired skin integrity, and risk for injury from CNS effects.
Teach lifestyle changes (regular exercise, weight loss, smoking cessation, low-sodium diet). Give with food to prevent GI distress. Monitor renal and hepatic function tests to catch developing failure and signal a dose reduction. Provide comfort measures (quiet environment, relaxation techniques). Teach the patient and family the drug's effects and what to report. Evaluate through blood pressure monitoring, watching for adverse effects (skin reactions, cough, headache), confirming understanding, and monitoring compliance.
Calcium-Channel Blockers
Calcium-channel blockers lower blood pressure, cardiac workload, and myocardial oxygen consumption. Because they cut cardiac workload significantly, they also treat angina.
Therapeutic Action
They block calcium ion movement across myocardial and arterial muscle cell membranes, altering the action potential and blocking contraction. The result is depressed myocardial contractility, slowed cardiac impulse through conductive tissue, and arterial dilation and relaxation.
Indications
Like ACE inhibitors and ARBs, used alone or combined with other agents for hypertension. Extended-release preparations are usually used for hypertension in adults.
By age group: calcium-channel blockers are the first drug group considered for children who need drug therapy for hypertension; they are not allowed in pregnancy; older adults are more prone to toxicity, so monitor renal and hepatic function.
Pharmacokinetics
| Route | Onset | Peak | Duration |
|---|---|---|---|
| Oral and extended release | 30-60 min | 6-11 h | Oral and extended-release |
| Half-life (T1/2) | Metabolism | Excretion |
|---|---|---|
| 5-7 h | Liver | Urine |
Contraindications and Cautions
Allergy to calcium-channel blockers. Heart block (sick sinus syndrome), worsened by the drug's conduction-slowing effect. Renal and hepatic impairment, which can alter metabolism and excretion and raise toxicity risk. Pregnancy and lactation, used only when benefit to the mother clearly outweighs risk to the fetus; it is unclear whether the drug enters breast milk, so use another feeding method in lactating mothers.
Adverse Effects
CNS: headache, dizziness, light-headedness, fatigue. CV: hypotension, bradycardia, peripheral edema, heart block. GI: nausea, hepatic injury. EENT: rash, skin flushing.
Interactions
Diltiazem increases serum levels and toxicity of cyclosporine. Grapefruit juice increases serum levels and toxicity of calcium-channel blockers.
Nursing Considerations
Assess for the contraindications above (headache, rash, bradycardia) and monitor cardiopulmonary status closely, since the drug can severely affect both systems. Relevant nursing diagnoses include decreased cardiac output from hypotension and vasodilation, and risk for injury from cardiovascular and CNS effects.
Teach lifestyle changes (regular exercise, weight loss, smoking cessation, low-sodium diet). Monitor blood pressure and heart rate and rhythm to catch adverse effects. Provide comfort measures (small frequent meals for nausea, limiting noise and controlling light and temperature to prevent stress that increases cardiac demand). Teach the patient and family the drug's effects and what to report, and stress strict adherence. Evaluate through blood pressure monitoring, watching for adverse effects, checking comfort measures, monitoring compliance, and tracking labs.
Vasodilators
Direct vasodilators are used when the other agents fail, and are reserved for severe hypertension and hypertensive emergencies.
Therapeutic Action
They act directly on smooth muscle, causing relaxation and vasodilation, which drops blood pressure.
Indications
Used only for hypertension that does not respond to other therapies. Nitroprusside maintains controlled hypotension during surgery. Nitroprusside is given intravenously, hydralazine is available oral, intravenous, and intramuscular, and minoxidil is oral only.
Pharmacokinetics
| Route | Onset | Peak | Duration |
|---|---|---|---|
| IV | 1-2 min | Rapid | 1-10 min |
| Half-life (T1/2) | Metabolism | Excretion |
|---|---|---|
| 2 min | Liver | Urine |
Contraindications and Cautions
Allergy to direct vasodilators. Cerebral insufficiency, worsened by a sudden drop in blood pressure. Peripheral vascular disease, CAD, heart failure, and tachycardia, all worsened by a sudden pressure drop. Pregnancy and lactation, used only when benefit to the mother clearly outweighs risk to the fetus; the drug enters breast milk and can harm the neonate, so use another feeding method if needed.
Adverse Effects
CNS: headache, dizziness, anxiety. CV: reflex tachycardia, heart failure, edema, chest pain. GI: nausea, vomiting, GI upset. EENT: rash, lesions (minoxidil is associated with abnormal hair growth). Nitroprusside is metabolized into cyanide and can cause cyanide toxicity, marked by dyspnea, ataxia, loss of consciousness, distant heart sounds, and dilated pupils. Nitroprusside also suppresses iodine uptake, leading to hypothyroidism.
Interactions
Each drug in this group acts differently, so check each one for drug-drug and drug-food interactions.
Nursing Considerations
Assess for the contraindications above (drug allergy, CAD, cerebral insufficiency). Get baseline weight, vital signs, skin condition, and labs (renal and hepatic function, serum electrolytes). Relevant nursing diagnoses include decreased tissue perfusion from changes in cardiac output, and acute pain from GI distress, headache, and skin effects.
Teach lifestyle changes (regular exercise, weight loss, smoking cessation, low-sodium diet). Monitor blood pressure and heart rate and rhythm closely to gauge effectiveness and respond fast if pressure falls too quickly or too far. Provide comfort measures (small frequent meals for nausea, limiting noise and controlling light and temperature). Watch for signs of fluid volume loss (vomiting, diarrhea, excessive sweating) to detect and treat excessive hypotension. Teach the patient and family the drug's effects and what to report, and stress strict adherence. Evaluate through blood pressure monitoring, watching for adverse effects (hypotension, GI distress, skin reactions), checking comfort measures, monitoring compliance, and tracking labs.
Frequently Asked Questions
What blood pressure now counts as hypertension?
Under the 2017 ACC/AHA guideline, hypertension starts at 130/80 mm Hg. Stage 1 is 130 to 139 systolic or 80 to 89 diastolic, and stage 2 is at or above 140 systolic or 90 diastolic. This lower threshold is why nearly half of U.S. adults now meet the definition.
Why are antihypertensives often combined?
Each class acts at a different point of blood pressure control, so combining them produces a synergistic effect and can lower doses of any single agent. Because hypertension is multifactorial, response varies between patients, and comorbidities like diabetes or a prior myocardial infarction can steer or rule out certain classes.
Why are ACE inhibitors and ARBs contraindicated in pregnancy?
Both act on the renin-angiotensin-aldosterone system and can cause fetal harm, so they are not used in pregnancy. Patients of childbearing potential taking them should use reliable contraception and report a suspected pregnancy promptly.
What is the key safety concern with IV nitroprusside?
Nitroprusside is metabolized into cyanide and can cause cyanide toxicity, marked by dyspnea, ataxia, loss of consciousness, distant heart sounds, and dilated pupils. It also suppresses iodine uptake and can lead to hypothyroidism, so monitor closely during controlled infusion.
Why should calcium-channel blockers not be taken with grapefruit juice?
Grapefruit juice inhibits the enzyme that clears these drugs, raising serum levels and the risk of toxicity such as excessive hypotension and bradycardia. Teach patients to avoid grapefruit juice while on the medication.