Identification of potential biomarkers of P-glycoprotein substrate neurotoxicity in transgenic mice expressing the mutated canine ABCB1 gene

Perspectives on the utility of moxidectin for the control of parasitic nematodes in the face of developing anthelmintic resistance

Macrocyclic lactone (ML) anthelmintics are the most important class of anthelmintics because of our high dependence on them for the control of nematode parasites and some ectoparasites in livestock, companion animals and in humans. However, resistance to MLs is of increasing concern. Resistance is commonplace throughout the world in nematode parasites of small ruminants and is of increasing concern in horses, cattle, dogs and other animals. It is suspected in Onchocerca volvulus in humans. In most animals, resistance first arose to the avermectins, such as ivermectin (IVM), and subsequently to moxidectin (MOX). Usually when parasite populations are ML-resistant, MOX is more effective than avermectins. MOX may have higher intrinsic potency against some parasites, especially filarial nematodes, than the avermectins. However, it clearly has a significantly different pharmacokinetic profile. It is highly distributed to lipid tissues, less likely to be removed by ABC efflux transporters, is poorly metabolized and has a long half-life. This results in effective concentrations persisting for longer in target hosts. It also has a high safety index. Limited data suggest that anthelmintic resistance may be overcome, at least temporarily, if a high concentration can be maintained at the site of the parasites for a prolonged period of time. Because of the properties of MOX, there are reasonable prospects that strains of parasites that are resistant to avermectins at currently recommended doses will be controlled by MOX if it can be administered at sufficiently high doses and in formulations that enhance its persistence in the host. This review examines the properties of MOX that support this contention and compares them with the properties of other MLs. The case for using MOX to better control ML-resistant parasites is summarised and some outstanding research questions are presented.

Loperamide-induced expression of immune and inflammatory genes in Collies associated with ivermectin sensitivity

This study evaluated the impact of the ABCB1-1Δ mutation in Collies which exhibited toxicity toward ivermectin, on changes in gene expression when given the unrelated ABCB1 substrate loperamide, to identify potential biomarkers predictive of drug safety. Thirty-two healthy intact Collies consisting of dogs with either a wild-type, heterozygous mutant, or homozygous mutant genotype were used. Whole blood samples were collected from Collies at 0 or 5 h following administration of loperamide at a dose of 0.10 mg/kg. Whole-genome gene expression microarray was conducted to examine for changes in gene expression. Microarray analysis identified loperamide-induced changes in gene expression which were specifically associated with ivermectin-sensitive phenotypes in Collies possessing the ABCB1-1Δ mutation. Gene pathway analysis further demonstrated that the altered genes are involved in immunological disease, cell death and survival, and cellular development. Thirteen genes, including CCL8 and IL-8, were identified. Collie dogs harboring ABCB1-1Δ mutation which also exhibited toxicity toward ivermectin demonstrated systematic responses following loperamide treatment exhibited by altered expression of genes involved in immune and inflammatory signaling pathways. Genes such as CCL8 and IL-8 are potential biomarkers in whole blood that may predict the safety of loperamide in dogs with ABCB1-1∆ mutation associated with ivermectin sensitivity.

Recognizing off-target drug effects in the gut and brain: revisiting isotretinoin and depression

Clinicians often face complex decisions regarding off-target drug effects, both in diagnosis and treatment. A key component in the formulation of the correct diagnosis is the temporal relationship between drug introduction and adverse effect. The sentinel injury may target the gut and brain. The description of the complaint may vary among providers. Modeling Information visualization for clinicians in real time will require the integration of time-stamped data with organ-specific complaints.