Medicines that impair kidney function
Three common mechanisms of drug-induced renal impairment are:• Reduced GFR caused by interference with the physiologic function of the kidney (e.g. NSAIDs reduce blood flow through the kidney). This is sometimes called functional renal impairment because the physical structure of the kidney is not damaged.
• Physical injury to parts of the kidney (e.g. necrosis of tubules with aminoglycosides). Traditionally, medicines that damage the nephron are termed nephrotoxic.
• Immune-based inflammatory reaction within the kidney presenting as glomerulonephritis (e.g. penicillins, gold salts).
NHS England's Think Kidneys programme includes guidelines for medicines optimisation in patients with acute kidney injury (AKI). This gives advice on managing patients with AKI that may be drug-induced and on medicines that may be harmful in AKI. From this document, medication identified as being especially likely to cause AKI can be remembered using the acronym CANDA: Contrast media, ACE inhibitors, NSAIDs, Diuretics and Angiotensin receptor blockers.
Drugs that are potentially harmful to the kidney should preferably be avoided in any patients with renal impairment as their renal reserve is less and any ill effects may lead to AKI. In end-stage renal failure, where patients are permanently on dialysis and GFR is typically less than 5mL/min, renal function cannot get any worse so the use of potentially nephrotoxic drugs is often acceptable if clinically indicated.