Many highly effective and selective anthelmintics are available, but such compounds must be used correctly, judiciously, and with consideration of the parasite/host interaction to obtain a favorable clinical response, accomplish good control, and minimize selection for anthelmintic resistance. Any decrease or increase of the recommended dose rate must always be discouraged. Underdosing is likely to result in lowered efficacy and possibly increased pressure for selection of resistance. Overdosing may result in toxicity without necessarily increasing product efficacy.
Most anthelmintics generally have a wide margin of safety, considerable activity against immature (larval) and mature stages of helminths, and a broad spectrum of activity. Nonetheless, the usefulness of any anthelmintic is limited by the intrinsic efficacy of the drug itself, its mechanism of action, its pharmacokinetic properties, characteristics of the host animal (eg, operation of the esophageal groove reflex), and characteristics of the parasite (eg, its location in the body, its degree of hypobiosis, susceptibility of the life stage, or susceptibility to the anthelmintic).
There are several classes of anthelmintics: benzimidazoles and probenzimidazoles, salicylanilides and substituted phenols, imidazothiazoles, tetrahydropyrimidines, organophosphates, macrocyclic lactones and, more recently introduced, the amino-acetonitrile derivatives, the cyclic octadepsipeptides, and the spiroindoles. Although it may be thought that chemotherapeutic control of helminth infections is currently satisfactory, selection for parasite resistance is an increasing concern.
Last full review/revision September 2014 by Jozef Vercruysse, DVM; Edwin Claerebout, DVM, PhD, DEVPC
I read an interesting article today that focused on stress and how it is related to premature death. It emphasized that it is not just large life events that cause damaging stress, but also how we ... READ MORE
Let’s talk about money. Despite what we all would like to think, most everything in the world revolves around money and the veterinary industry is not any different.... READ MORE
In the past two weeks, I’ve taken five midterms, two quizzes, given a presentation, and studied every spare minute of every day. I spent my days in class and my nights hunched over my texts, ... READ MORE
