ARBs

Summary

ARBs, or angiotensin receptor blockers, are drugs ending in -sartan, like losartan, candesartan, and valsartan. They work by blocking angiotensin II receptors.

This blocks the constriction of the efferent arterioles of the glomerulus, which can decrease intraglomerular pressure and reduce the glomerular filtration rate.  This can help block any thickening of the glomerular basement membrane. ARBs may lead to an increase in renin levels. 

Clinically, ARBs are mainly used in patients who cannot tolerate ACE inhibitors. They may be used to treat heart failure, where they have been shown to reduce mortality. They can also be used to treat hypertension and can help prevent unfavorable heart remodeling in chronic hypertension.  ARBs may also be used to treat proteinuria, renal failure, and diabetic nephropathy.

Potential side effects of ARBs include hypotension, increased creatinine levels, and hyperkalemia. They should be used with caution in patients with bilateral renal artery stenosis. ARBs are also teratogenic and can cause fetal renal malformations, so they should be avoided in pregnancy.

Key Points

• Angiotensin II Receptor Blockers (ARBs)
  • Drug Names
    • -sartan Ending
      • Losartan
      • Candesartan
      • Valsartan
  • Mechanisms
    • Selectively blocks angiotensin II receptors
      • Blocks the angiotensin II type 1 receptor (AT1 receptor)
    • Effects similar to ACE Inhibitors, but do not increase bradykinin
      • Prevents constriction of efferent arterioles of glomeruli
        • ↓ GFR
        • Decreases intraglomerular pressure
        • Blocks thickening of glomerular basement membrane
      • ↑ Plasma Renin
        • due to loss of negative feedback
  • Clinical Use
    • Used in Patients who cannot tolerate ACE inhibitors
      • e.g. due to cough or angioedema
      • ACE Inhibitors are still preferred due to longer history of use and stronger evidence of clinical benefit
    • Treats hypertension
      • Prevents unfavorable cardiac remodeling (in chronic HTN)
      • ACEIs are still first-line, since ACEIs are proven to reduce mortality in HTN, while ARBs do not
      • Used in hypertension and heart failure due to left ventricular systolic dysfunction
    • Treats heart failure
      • Reduces mortality
        • Though there is less evidence of a mortality benefit with ARBs than with ACE Inhibitors
    • Treats proteinuria
    • Treats chronic kidney disease
    • Treats diabetic nephropathy
      • Decreases rate of glomerular basement membrane thickening, prevents progression to chronic kidney disease
  • Side Effects
    • Hypotension
    • Hyperkalemia
    • Increase creatinine
      • Due to decrease in GFR
    • Teratogen
      • May cause fetal kidney malformations
    • Use with Caution in Bilateral renal artery stenosis
      • In bilateral renal artery stenosis, angiotensin II is necessary to maintain GFR. Inhibiting angiotensin II’s effects can lead to rapid renal failure.