Oxibendazole is a benzimidazole drug that interferes with metabolic pathways, used to protect against roundworms, strongyles, threadworms, pinworms and lungworm infestations in horses and some domestic pets.

Oxibendazole shows a significant reduction of the proportion of positive foals after treatment. Oxibendazole significantly reduces the proportion of positive horse foals on six of the seven farms (86%). [1] Oxibendazole reduces in the number of strongyle eggs/g (epg) in horse, but the reduction is only by 82% with an upper confidence limit of 89%. [2] Oxibendazole results in collapse of the lip papillae, rupture of buccal cavity cuticle, prolapse of the pharynx, degeneration of epithelial cells and erosion of microvilli in adult Ascaris suum, theses changes may lead to impaired digestion and absorption of nutrients and cause cellular autolysis, resulting in the death of the worm. [3] Oxibendazole reduces faecal worm egg counts (EPG) by 97.6% for Toxocara canis, 95.7% for Trichuris vulpis, 94.6% for Ancylostoma caninum, and 100% for Toxascaris leonine in dogs and cats. [4] Oxibendazole could only be detected in plasma at the 0.5 hours and 1.0 hours post administration sampling times and the mean maximum plasma concentration is 0.008 mg/mL in horse. Oxibendazole is detected in faeces between 12 and 72 hours after administration and the highest dry faecal concentration was detected at 24 hours. [5]