Pharmacokinetics of intravascular itraconazole in the American horseshoe crab (Limulus polyphemus)

Pharmacokinetics and bioavailability of itraconazole oral solution in cats

OBJECTIVES

The aim of this study was to describe the pharmacokinetics and bioavailability of itraconazole (ITR) oral solution in healthy cats.

METHODS

The pharmacokinetics of ITR were studied in eight healthy, fasted cats after a single intravenous (IV) and oral (PO) administration at a dose of 5 mg/kg, in a two-period crossover design study. Blood was obtained at predetermined intervals for the determination of ITR concentrations with high-performance liquid chromatography. Pharmacokinetic characterisation was performed by a non-compartmental method using WinNonlin 5.2.1.

RESULTS

After IV administration, the major pharmacokinetic parameters were as follows (mean ± SD): terminal elimination half-life (T1/2λz ) 15.8 ± 1.88 h; area under the curve from time zero to infinity (AUC0-∞ ) 13.9 ± 3.17 h·μg/ml; total body clearance 0.37 ± 0.08 l/h/kg; apparent volume of distribution 8.51 ± 1.92 l/kg; mean residence time 20.6 ± 3.95 h. After PO administration, the principal pharmacokinetic parameters were as follows (mean ± SD): T1/2λz 15.6 ± 3.20 h; AUC0-∞ 7.94 ± 2.83 h·μg/ml; peak concentration 0.70 ± 0.14 μg/ml; time of peak 1.43 ± 0.53 h. The absolute bioavailability of ITR oral solution after oral administration was 52.1 ± 11.6%.

CONCLUSIONS AND RELEVANCE

The disposition of ITR oral solution in cats is characterised by a long terminal half-life, a short peak time and moderate bioavailability.

Zoothamnium duplicatum infestation of cultured horseshoe crabs (Limulus polyphemus)

An outbreak of the sessile peritrich Zoothamnium duplicatum in a pilot, commercial-scale Limulus polyphemus hatchery resulted in the loss of ∼96% (40,000) second/third instar larvae over a 61day period. peritrich growth was heavy, leading to mechanical obstruction of the gills and physical damage. The peritrichs were controlled without resultant loss of juvenile crabs by administering 10ppm chlorine in freshwater for 1h and the addition of aquarium grade sand; a medium into which the crabs could burrow and facilitate cleaning of the carapace. Peritrich identity was confirmed from a partial SSU rDNA contiguous sequence of 1343bp (99.7% similarity to Z. duplicatum).

Fusarium solani species complex associated with carapace lesions and branchitis in captive American horseshoe crabs Limulus polyphemus

Captive American horseshoe crabs Limulus polyphemus housed at the National Aquarium presented with a variety of shell and gill lesions over a 3 yr period. Carapace lesions were located on both the dorsal and ventral prosoma and opisthosoma and included multifocal circular areas of tan discoloration, ulcerations, and/or pitting lesions, extending from superficial to full thickness. Gill lesions involved both the book gill cover (operculum) and individual book gill leaflets and included multifocal circular areas of tan discoloration, tan to off-white opaque proliferative lesions, and/or areas of black discoloration. Histopathology revealed fungal hyphae, with variable morphology throughout the thickened and irregular cuticle of the carapace and occasionally penetrating into subcuticular tissues, with associated amebocytic inflammation. Book gill leaflets were infiltrated by fungal hyphae and contained necrotic debris and amebocytes. Thirty-eight of 39 animals (97%) evaluated via histopathological examination had intralesional fungal hyphae. Fungal cultures of carapace and gill lesions were attempted in 26 tissue samples from 15 individuals and were positive in 13 samples (50%), with 10 cultures (77%) yielding identification to genus. Fusarium sp. was identified in 8 of the 10 cultures (80%) via culture morphology. The Fusarium solani species complex was confirmed in 6 of these 8 (75%) via polymerase chain reaction amplification of 2 different ribosomal-specific sequences of isolated fungal DNA. Ante-mortem systemic and topical treatments were performed on some affected individuals, but no appreciable change in lesions was observed. Mycotic dermatitis and branchitis are serious health issues for captive American horseshoe crabs.