Dosage of once-daily gentamicin in spinal cord injury patients

In patients with spinal cord injury (SCI), serum creatinine does not accurately reflect the level of renal function. Therefore, in SCI patients, the dose of potentially nephrotoxic drugs should be adjusted on an individual basis from the estimated creatinine clearance.

A 41-year-old male with tetraplegia due to cervical spinal cord injury underwent extended pyelolithotomy for staghorn calculus in the right kidney. The blood urea level was 9.9 mmol/l; creatinine was 112 umol/l (reference range: 0-135). We were conscious of this patient's renal disease, and therefore, administered only 3 mg/kg of gentamicin (240 mg) instead of the standard dose of 5 mg/kg body weight. Despite taking this precaution, the gentamicin level measured 22.5 h after the initial dose, was in the potentially toxic range 3.3 mg/l.

We recommend that even the first dose of gentamicin in the once-daily regimen, which is 5 mg/kg, should be individualised in SCI patients based on age, sex, weight, height, level of spinal cord injury, and renal function.