Efficacy and tolerability of high-dose cefalexin 45 mg/kg/dose (maximum 1.5 g) three times daily in children with bone and joint infections.

Background: Cefalexin, a first-generation cephalosporin, is commonly used as oral continuation therapy for paediatric bone and joint infections (BJIs). The standard four times daily cefalexin dose makes treatment adherence challenging. A pharmacokinetic modelling study found that a cefalexin dose of 45 mg/kg (maximum 1.5 g) three times daily achieves the same pharmacodynamic target.

Objectives: To evaluate the efficacy and tolerability of three times daily cefalexin dosing in children with BJIs.

Patients and methods: Retrospective audit of children aged 1-18 years who received cefalexin at a dose of 40-50 mg/kg (maximum 1.5 g) three times daily as oral continuation therapy for a haematogenous BJI at a quaternary paediatric hospital in Australia over a 4 year period (January 2019 to December 2022).

Results: Of 149 children with BJIs treated with three times daily cefalexin dosing, the majority (147/149; 99%) achieved cure, with two experiencing recurrence of their infection. Most children tolerated the higher cefalexin dose; 4 children experienced gastrointestinal symptoms and 13 developed neutropenia, which was mild in most cases with no associated complications.

Conclusions: A reduced frequency dosing regimen using a high cefalexin dose of 45 mg/kg (maximum 1.5 g) three times daily is effective and well tolerated in most children with BJIs.