Fluconazole Pharmacokinetics in the Galleria mellonella Larvae and performance evaluation of a Bioassay compared to LC-MS/MS for haemolymph specimens. [PublishAheadOfPrint]

The invertebrate model Galleria mellonella can be used to assess treatment efficacy of fungal infection. The fluconazole dose best mimicking human exposure during licensed dosing is unknown. We validated a bioassay for fluconazole detection in haemolymph and determined the fluconazole pharmacokinetics and pharmacodynamics in larvae haemolymph in order to estimate a humanized dose for future experiments.

A bioassay using 4 mm agar-wells, 20 μl haemolymph and the hyper-susceptible Candida albicans DSY2621 was established and compared to a validated LC-MS/MS. Galleria mellonella larvae were injected with fluconazole (5, 10 and 20 mg/kg) and haemolymph harvested for 24 h for pharmacokinetics calculations. The exposure was compared to the human exposure during standard licensed dosing.

The bioassay had a linear standard-curve between 1-20 mg/L. Accuracy and coefficients of variation (%) values were below 10%. The Spearman coefficient between assays was 0.94. Fluconazole larval pharmacokinetic followed one-compartment linear kinetics, with AUC_24h being 93, 173 and 406 mg*h/L for the three doses compared to 400 mg*h/L in humans under licensed treatment.

In conclusion, a bioassay was validated for fluconazole determination in haemolymph. The pharmacokinetics was linear. An exposure comparable to the human exposure during standard licensed dosing is obtained with 20 mg/kg.

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