Expansion
Reduce the dose or lengthen the interval for renally cleared drugs
Expansion
Drugs needing dose reduction (renally cleared, narrow therapeutic index)
- Digoxin, lithium, metformin
- Aminoglycosides, vancomycin, many other antibiotics
- Low molecular weight heparin, direct oral anticoagulants
- Opioids, particularly morphine, whose active metabolite accumulates causing sedation and myoclonus; oxycodone or alfentanil are preferred
Drugs to avoid or use with caution because they worsen renal function
- NSAIDs: remove the prostaglandin-mediated afferent dilatation
- ACE inhibitors and angiotensin receptor blockers: remove efferent constriction
- Contrast media, aminoglycosides, ciclosporin
- The triple whammy of an ACE inhibitor, a diuretic and an NSAID together
Drugs that become ineffective
- Thiazides below an eGFR of about 30
- Nitrofurantoin, which needs renal concentration to work in the urine
Practical approach: check whether the drug is renally cleared, use creatinine clearance for dosing, consider a loading dose unchanged (volume of distribution is usually normal) with a reduced maintenance dose, monitor levels where available, and review with each change in renal function including acute illness.