What dosage reduction is required for a patient with a creatinine clearance of 15 ml/min being treated with gentamicin?

For a patient with normal renal function, the advised dose is 3-7 mg/kg daily, divided into one to three doses, which normally calculates out for a 60 kg patient at 80-120 mg tds. In renal impairment, with a CCr of 10-30 ml/min, the dose is reduced to 80 mg every 24 hours.

For further information on dose adjustment for a range of commonly used drugs: Bunn R and Ashley C. Eds Renal Drug Handbook or Bennet W et al. Drug Prescribing in Renal Failure.