Overview
Prescribing drugs in patients with reduced renal function can lead to problems via multiple mechanisms:
- Reduced renal excretion of the drug and/or its metabolites can cause toxicity
- Even if elimination is not impaired, some people may have increased sensitivity
- Patients with poor renal function may have worse side effects
- Drugs may be less effective in those with renal impairment
The estimated glomerular filtration rate (eGFR) or creatinine clearance (CrCl) is used to estimate renal function.
To overcome the above problems, the following approaches are taken:
- Increasing the interval between doses or
- Decreasing the dose or
- A combination of both
Drugs that are usually safe in acute kidney injury (AKI)
Some common drugs that are usually safe in AKI are:
- Paracetamol
- Aspirin (at a cardioprotective dose)
- Clopidogrel
- Warfarin
- Statins
- Beta-blockers
Drugs that should be stopped in AKI
These drugs should be stopped as they may worsen an AKI:
- NSAIDs (except low-dose cardioprotective aspirin)
- ACE inhibitors
- Angiotensin II receptor blockers (ARBs)
- Aminoglycosides (e.g. gentamicin)
- Diuretics
Drugs with an increased risk of toxicity in AKI
Drugs that may be stopped as an AKI can increase toxicity, but they do not usually worsen the AKI itself:
- Metformin – due to increased risk of lactic acidosis
- Lithium – due to increased risk of lithium toxicity
- Digoxin – due to increased risk of digoxin toxicity
Drugs causing pre-renal damage
Any drug that causes volume depletion or reduced renal perfusion may cause pre-renal damage. Some examples are:
- NSAIDs
- ACE inhibitors
- ARBs
Drugs causing intrarenal damage
These drugs may be directly nephrotoxic or lead to hypersensitivity reactions:
- Drugs that may cause glomerulonephritis:
- Rifampicin
- Sulfonamides
- Penicillamine
- Drugs that may cause acute interstitial nephritis:
- Antibiotics – generally penicillins and cephalosporins
- Sulfonamides
- Thiazide diuretics
- Drugs that are directly nephrotoxic and may cause acute tubular necrosis:
- Aminoglycosides (e.g. gentamicin)
- Amphotericin
- Ciclosporin
Drugs causing post-renal damage
These drugs may lead to urinary tract obstruction:
- Anticholinergic drugs (e.g. tricyclic antidepressants) may cause acute urinary retention
- Acetazolamide, methotrexate, and sulfonamides can cause crystalluria which can lead to obstruction
