Evaluation of dosage adjustment in patients with renal impairment

Aims: To determine whether appropriate dosage adjust-ments are made in patients with significant renal impairment for drugs with a high fractional renal clearance. Methods: Evaluation of dosage adjustment was performed in patients who were admitted to a 480-bed metropolitan hospital (Princess Alexandra Hospital, Brisbane, Australia) with an estimated creatinine clearance of less than or equal to40 mL/min. All drugs had a high fractional renal excretion. A prescribed dose within 30% of the calculated dose was considered appropriate. Results: Doses were found to be inappropriately high in 105 (42.2%) of 249 admission prescriptions of the targeted drugs. Doses were appropriately reduced in hospital in 32 patients (30.4%). Seventy-three (29.3%) prescriptions were continued with excessive doses. Only 34 prescriptions for the target drugs were initiated in hospital, of which 88.2% were appropriately dosed. Conclusions: A significant percentage of patients with renal impairment are admitted to hospital on inappro-priately high doses of drugs, with a high fractional renal excretion and low therapeutic index. Doses are appropriately reduced in hospital in some patients but there is still room for improvement.