It is often thought that medicines that accumulate in patients with renal impairment will cause further nephrotoxicity. This is not the case. Medicine accumulation will result in organ damage similar to that of an overdose. For example:

• Some cephalosporins, penicillins, carbapenems in very high doses will lead to grand mal seizures
•  Opioids (especially morphine and pethidine) are metabolised to active metabolites that cause excessive respiratory depression and sedation
• Metformin – accumulation leads to lactic acidosis. It should not be prescribed in patients with GFR <30 mL/min
• Aminoglycosides – overdosage leads to irreversible nephrotoxicity and ototoxicity
• Allopurinol – build up leads to bone marrow suppression.

High-risk medicines and actions

When a patient is admitted with an acute kidney infection (AKI), a thorough review of medication is required:

• To eliminate potential causes, risks and contributory factors 
• To avoid inappropriate combinations of medicines 
• To ensure all prescribed medicines are clinically appropriate.