Method Validation for the Determination of Ciprofloxacin in <i>Lucilia sericata</i> Larvae via Capillary Electrophoresis Combined With Mass Spectrometry

Substances derived from insects can serve therapeutic functions due to their diverse biological properties. This article focuses on the species Lucilia sericata and the benefits of larval therapy in patients who, due to hospitalization, have developed pressure ulcers and other difficult-to-heal wounds. Larval therapy, also known as maggot debridement therapy, employs sterile fly larvae to treat chronic, non-healing wounds by enzymatically degrading necrotic tissue and decreasing bacterial colonization. The larvae are applied to the wound for a period of 48-72 h, during which they effectively clean the wound and stimulate tissue regeneration. This therapeutic approach is particularly efficacious for recalcitrant wounds, such as diabetic foot ulcers and pressure sores, which have not responded to conventional treatments. Larvae may also constitute an alternative material in entomotoxicological studies to detect substances ingested at not only toxic but also therapeutic doses. The present work describes a method for assaying ciprofloxacin in L. sericata larvae using capillary electrophoresis coupled to mass spectrometry. The developed method features high sensitivity with a limit of quantification of 100 ± 0.018 ng/mL, as well as accuracy and precision estimated within 87%-103% and 1%-4%, respectively. An application of a simple and fast precipitation of proteins procedure for sample cleaning resulted in a highly satisfactory recovery of the analyte (90%-104%). The method was linear in a range of 100-1000 ng/mL with a determination coefficient higher than 0.9973. The method was used to determine ciprofloxacin in larval homogenate after antibiotic administration to the patient at a dose of 500 mg twice daily per os during application of the larvae dressing. Ciprofloxacin was shown to distribute from the patient's circulation to the larvae at a concentration of 150 ng/mL (750 ng/g).