Long-acting antiparasitic formulations are used widely because they help prevent and treat parasitic infections and reduce the frequency of administration(and the associated handling and restraint of livestock).We formulated a soluble,glass-based,sustained-release bolus of ivermectin(IVM)that was delivered over a period of 3 months.To ascertain if the new IVM formulation could have clinical use,we investigated its pharmacokinetics in goats.Animals were administered the IVM bolus(30 mg/kg body weight)or injected intravenously with IVM(0.2mg/kg body weight).Pharmacokinetic analyses were undertaken using a non-compartmental model.After intravenous administration,the half-life(t1/2),volume of distribution(Vd),plasma clearance(Cl),area under the time–concentration curve(AUC0–t)and mean residence time(MRT0–t)of IVM were 5.68±1.14 days,12.13±2.34 L/kg,1.51±0.32 L/day/kg,114.4±19.8 days*ng/mL,and 3.37±0.68 days,respectively.After oral administration,the peak plasma concentration(Cmax),time to maximum concentration(Tmax),t1/2,AUC0–t and MRT0–t of IVM were 11.54±1.77 ng/mL,1.88±2.73 days,30.76±2.06 days,239.4±29.8 days*ng/mL,and 27.68±2.04 days,respectively.IVM concentrations in plasma exceeded 5 ng/mL within 14 days and 1 ng/mL for ≥90 days after bolus administration.Thus,the novel IVM bolus described here is a sustained-release formulation.Our results suggest that soluble,glass-based boluses could be drug-delivery devices for anthelmintic agents in cattle and goat industries.