Pharmacokinetic and clinical data supporting the use of fondaparinux 1.5 mg once daily in the prevention of venous thromboembolism in renally impaired patients

The study aim was to determine the value of fondaparinux at the once-daily 1.5 mg dose in patients with moderate renal impairment (creatinine clearance between 20 and 50 ml/min). Pharmacokinetic simulations were performed using a population pharmacokinetic model based on data obtained in 756 patients undergoing major orthopedic surgery. The efficacy (venous thromboembolism) and safety (major bleeding) of 1.5 mg fondaparinux were determined by analyzing the available data obtained in all thromboprophylaxis trials using this dosage. The predicted steady-state exposure [area under the plasma concentration-time curve from 0 to 24 h (AUC0-24)] to fondaparinux between patients with moderate renal impairment receiving 1.5 mg and patients with normal renal function receiving 2.5 mg was similar. In four phase II trials (two trials versus placebo, one versus enoxaparin and one without comparator), 353 patients undergoing total hip or knee replacement (10.8% with moderate renal impairment) received fondaparinux 1.5 mg. The overall rate of venous thromboembolism and major bleeding was 10.4 and 0.3%. Fondaparinux 1.5 mg was significantly more effective than placebo (P < 0.01) and was as effective as, and tended to be safer (P = 0.05) than, twice-daily 30 mg enoxaparin. The effect was maintained in patients with moderate renal impairment. The once-daily administration of 1.5 mg fondaparinux in patients with moderate renal impairment resulted in a predicted exposure to the drug similar to that achieved with 2.5 mg in patients with normal renal function. This dosage regimen showed a favorable efficacy/safety clinical profile and should be appropriate in preventing venous thromboembolism in patients with moderate renal impairment.