Canine Intestinal Organoids as a Novel In Vitro Model of Intestinal Drug Permeability: A Proof-of-Concept Study.

A key component of efforts to identify the biological and drug-specific aspects contributing to therapeutic failure or unexpected exposure-associated toxicity is the study of drug-intestinal barrier interactions. While methods supporting such assessments are widely described for human therapeutics, relatively little information is available for similar evaluations in support of veterinary pharmaceuticals. There is, therefore, a critical need to develop novel approaches for evaluating drug-gut interactions in veterinary medicine. Three-dimensional (3D) organoids can address these difficulties in a reasonably affordable system that circumvents the need for more invasive in vivo assays in live animals. However, a first step in developing such systems is understanding organoid interactions in a 2D monolayer. Given the importance of orally administered medications for meeting the therapeutic need of companion animals, we demonstrate growth conditions under which canine-colonoid-derived intestinal epithelial cells survive, mature, and differentiate into confluent cell systems with high monolayer integrity. We further examine the applicability of this canine-colonoid-derived 2D model to assess the permeability of three structurally diverse, passively absorbed ß-blockers (e.g., propranolol, metoprolol, and atenolol). Both the absorptive and secretive apparent permeability (Papp) of these drugs at two different pH conditions were evaluated in canine-colonoid-derived monolayers and compared with that of Caco-2 cells. This proof-of-concept study provides promising preliminary results with regard to the utility of canine-derived organoid monolayers for species-specific assessments of therapeutic drug passive permeability.

Enteropathy and bone marrow hypoplasia associated with presumptive albendazole toxicosis in a juvenile Boer goat.

Albendazole is a widely used anthelmintic drug that is labeled for the treatment of specific nematodes and flukes in ruminants. Albendazole is approved for the treatment of liver flukes in goats (10 mg/kg PO for a single dose), but is commonly used extra-label in situations in which parasite resistance is an issue. Albendazole toxicosis has been reported in pigeons, doves, alpacas, humans, dogs, and cats. Here we report an adverse event in a 6-mo-old goat associated with extra-label use of albendazole (35.7 mg/kg PO daily for 3 d). Clinicopathologic findings included severe diarrhea and death, with small intestinal crypt necrosis and dysplasia, and severe bone marrow hypoplasia. Microbial and molecular testing and transmission electron microscopy ruled out infectious organisms. The described pathologic changes are similar to those reported in other species that have experienced toxicosis associated with albendazole. To our knowledge, bone marrow and intestinal lesions associated with albendazole use in the goat have not been reported previously. Veterinarians should be aware of potential adverse events and toxicoses associated with anthelmintic drugs, especially as parasite resistance increases, and extra-label usage, and the use of such drugs without veterinary supervision, becomes more common.

Rapid untargeted screening for drug residues in animal tissues with liquid microjunction surface sampling probe mass spectrometry.

An untargeted screening method for the rapid identification of veterinary drug residues in incurred animal tissues using liquid microjunction surface sampling probe mass spectrometry (LMJSSP-MS) was developed. Current analytical methods for veterinary drug residue screening involve lengthy sample preparation, extraction, and instrumental analysis steps. This method identifies veterinary drug residues in several different incurred animal tissues more quickly than conventional analytical methods. This LMJSSP-MS method uses an ambient ionization technology called liquid microjunction surface sampling probe along with a data dependent scan function of a quadrupole orbitrap mass spectrometer. Collected product ion spectra are searched against the mzCloud™ online mass spectral database to identify veterinary drug residues found in incurred animal tissue samples. Examples of veterinary drugs identified with this method include flunixin, tilmicosin, pentobarbital, xylazine, and ketamine. Optimization of method parameters is described and discussed. The limit of identification (LOI) of this method is estimated to be approximately 1 µg g-1 for xylazine and ketamine.