Purpose: Fondaparinux, a selective activator factor X (factor Xa) inhibitor, is effective and safe for preventing venous thromboembolism after major orthopaedic surgery (MOS) at the once-daily subcutaneous dose of 2.5 mg. As the drug is mainly eliminated by the kidneys, a reduced dosage (1.5 mg once daily) was developed for patients with renal impairment.
Methods: We studied the pharmacokinetics (PK) of this dosage regimen using data from a real-world cohort of 442 patients with renal impairment (creatinine clearance 20-50 ml/min) undergoing MOS. Data were analysed using NON-linear Mixed Effect Modelling software (NONMEM) software. Fondaparinux PK was modelled using a two-compartment model with first-order absorption.
Results: This analysis confirmed the relationship between renal function and fondaparinux PK profiles. The mean predicted steady-state area under the plasma concentration time curve, peak and trough plasma concentrations of fondaparinux were lower by 15.6 %, 13.0 % and 10.3 %, respectively, in patients with renal impairment treated with 1.5 mg compared with patients with normal renal function treated with 2.5 mg (p < 0.01).
Conclusion: Although administration of 1.5 mg fondaparinux in patients with renal impairment resulted in a predicted exposure slightly lower than that achieved with 2.5 mg in patients with normal renal function, fondaparinux 1.5 mg is a valuable thromboprophylactic option in MOS patients with renal impairment who are at risk of bleeding.