Angiotensin II Receptor Blockers (ARBs) are antihypertensive agents that block angiotensin II from binding to its receptors, promoting vasodilation and reducing blood pressure—commonly used to manage hypertension, heart failure, and diabetic kidney disease.
Name of the Angiotensin II Receptor Blockers (ARBs) drugs:
- Candesartan
- Losartan
- Valsartan
- Irbesartan
Mechanism of action:
Acts as antagonists at angiotensin II (Type 1) receptors. This prevents angiotensin – II mediated effects (arteriolar constriction and aldosterone release) resulting in reduced afterload and reduced circulating volume, thereby reducing BP.
Indications
- Hypertension
- Heart Failure (result in improved survival in LV dysfunction)
- Diabetic Nephropathy in type 2 diabetes.
| Candesartan |
| Availability: Tablets: 4 mg, 8 mg, 16 mg, 32 mg. |
| Administration/handling: PO: • Give without regard to food |
| Hypertension Note: Antihypertensive effect usually seen in 2 weeks. Maximum effect within 4–6 weeks |
| PO: Adults, elderly: Initially, 8–16 mg once daily. Titrate to response. Range: 8–32 mg/day in 1–2 divided doses. Children 6–16 YRS, More than 50 kg: Initially, 8–16 mg/day in 1–2 divided doses. Range: 4–32 mg. Maximum: 32 mg/day. 50 KG OR LESS: Initially, 4–8 mg in 1–2 divided doses. Range: 2–16 mg/day. Maximum: 32 mg/ day. Children 1–5 yrs: Initially, 0.2 mg/kg/ day in 1–2 divided doses. Range: 0.05–0.4 mg/kg/day. Maximum: 0.4 mg/kg/day |
| HF PO: Adults, elderly: Initially, 4–8 mg once daily. May double dose at approximately 2-wk intervals up to a target dose of 32 mg/day |
| Losartan |
| Availability: Tablets: 25 mg, 50 mg, 100 mg |
| Administration/handling: PO: May give without regard to food. |
| Hypertension PO: Adults, elderly: Initially, 25–50 mg once daily. May increase as needed to 100 mg/day in 1–2 divided doses. Children 6–16 yrs: Initially, 0.7 mg/kg (maximum: 50 mg) once daily. Adjust dose to BP response. Maximum: 1.4 mg/kg or 100 mg/day |
| Diabetic Nephropathy PO: Adults, elderly: Initially, 50 mg/ day. May increase to 100 mg/day based on B/P response. |
| Stroke Prevention (Hypertension with Left Ventricular Hypertrophy) PO: Adults, elderly: Initially, 50 mg/ day. Maximum: 100 mg/day based on BP response. Should be used in combination with a thiazide diuretic. |
| Valsartan |
| Availability: tablets: 40 mg, 80 mg, 160 mg, 320 mg |
| Administration/handling: PO • Give without regard to food. |
| Hypertension PO: ADULTS, ELDERLY: Initially, 80–160 mg/day in pts who are not volume depleted. Maximum: 320 mg/day. CHILDREN 6–16 YRS: Initially, 1.3 mg/kg once daily (Maximum: 40 mg). May increase up to 2.7 mg/kg once daily (Maximum: 160 mg/day). |
| HF PO: ADULTS, ELDERLY: Initially, 20–40 mg twice daily. May increase up to 160 mg twice daily. Maximum: 320 mg/day |
| Post-MI, Left Ventricular Dysfunction PO: ADULTS, ELDERLY: May initiate 12 hrs or longer following MI. Initially, 20 mg twice daily. May increase within 7 days to 40 mg twice daily. May further increase up to target dose of 160 mg twice daily. |
| Irbesartan |
| Availability: Tablets: 75 mg, 150 mg, 300 mg. |
| Administration/handling: PO • Give without regard to food. |
| Hypertension PO: ADULTS, ELDERLY, CHILDREN 13 YRS AND OLDER: Initially, 75–150 mg/day. May increase to 300 mg/day. CHILDREN 6–12 YRS: Initially, 75 mg/day. May increase to 150 mg/day. |
| Diabetic Nephropathy PO: ADULTS, ELDERLY: 300 mg once daily. |
Metabolism and Half-life
Variable – e.g., valsartan (t ½ 6h) is excreted largely unchanged via the biliary route; losartan (t ½ of the active metabolite is 6-9h) is excreted via biliary and urinary routes.
Monitoring:
- Monitor U& Es for renal impairment prior to and 1-2 weeks after commencing treatment.
- Once stable on therapy U&Es must be checked at least annually.
- Careful clinical monitoring is required when used in severe heart failure.
Cautions & Contraindications:
- Pregnancy – may cause fetal injury
- Renal artery stenosis.
- Caution in peripheral vascular disease as this may be associated with undiagnosed renal artery stenosis.
- Use with Caution in hypotension, hypovolemia, hyperkalemia, renal and hepatic disease.
Side – effects:
- Hypotension (may get severe first-dose hypotension)
- Renal Impairment
- Hyperkalemia
- Angioedema (rare)
- Headache
- Dizziness
- Tachycardia
- Hypoglycemia
Drug interactions:
- Risk of profound first-dose hypotension with loop diuretics and enhanced hypotensive effect with other antihypertensive agents.
- Increased risk of renal impairment with NSAIDs. NSAIDs (e.g., ibuprofen, ketorolac, naproxen) may decrease antihypertensive effect.
- Enhanced hypoglycemic effect of insulin, metformin and sulfonylureas.
- Effects are antagonized by corticosteroids.
Important points:
ACEIs inhibit ACE-mediated breakdown of bradykinin; bradykinin stimulates vagal afferent nerve fiber and produce a refractory dry cough. This side- effect does not occur with ARBs as they do not act directly on ACE. ACEIs/ARBs are less effective in African/Caribbean patients due to ACE polymorphisms.
NURSING CONSIDERATIONS
Baseline assessment
- Vital signs, ECG, CBC, Urine analysis, sodium, potassium, creatinine and BUN.
- Female clients of childbearing age: obtain negative pregnancy test. Let healthcare provider know if they plan to become pregnant.
- If medication is prescribed for heart failure: Assess weight, lung sounds & presence of edema or dyspnea.
Patient & Family Education:
- Hypotension can occur with first few doses-hence to be mindful of any dizziness and weakness and make position changes slowly
- Angioedema – less common, but serious side effect. Seek immediate medical attention.
- Avoid potassium supplements & salt substitutes that contain potassium.
- NSAIDs can reduce antihypertensive effect of the medication.
- Life – style modifications.
- Not to stop treatment abruptly.
REFERENCES
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
Stories are the threads that bind us; through them, we understand each other, grow, and heal.
JOHN NOORD
Connect with “Nurses Lab Editorial Team”
I hope you found this information helpful. Do you have any questions or comments? Kindly write in comments section. Subscribe the Blog with your email so you can stay updated on upcoming posts and the latest articles.
