Unravelling the pharmacokinetics of triazole antifungals in snakes

Submitted by ROrritt on 9 November 2017

The first published paper to report on the pharmacokinetics of triazole antifungals in snakes has been published in the Journal of Zoo and Wildlife Medicine.

This study is of particular relevance in light of an emerging condition known as ‘snake fungal disease’ (SFD) caused by the pathogen Ophidiomyces ophiodiicola, which may prove to be a threat to endangered populations. Snakes and other reptiles are also susceptible to disease caused by various Aspergillus species.

Lindemann and colleagues set out to investigate the metabolism of voriconazole and itraconazole in pitvipers. Their main study used apparently healthy, wild-caught cottonmouths (Agkistrodon piscivorus; a type of pitviper) as test subjects.

Safe dosing of triazoles may be a particular problem in pitviper species. The researchers found that, out of 11 healthy snakes receiving voriconazole (5-10mg/kg), 4 died within 12 hours of receiving the drug. The authors also discuss the possibility of neurotoxic effects of voriconazole in pitvipers, prompted by the observation of neuropathies after dosing. However, no control population was studied, so it is not entirely certain that these effects were due to the drug. The surviving subjects maintained potentially therapeutic doses of >250ng/ml (effective against O. ophiodiicola based on in vitro data) for 12-24 hours.

A per-cloacal suspension of itraconazole (10mg/kg) did not result in any deaths in 7 cottonmouths, but therapeutic levels (>1000ng/ml for O. ophiodiicola based on in vitro data) were not reached.

Although the results of this study suggest that there is potential for therapeutic use of triazole antifungals in pitvipers, safety and appropriate therapeutic protocols are yet to be determined.