Ivermectin is an antiparasitic medicine (i.e. a medicine used to eliminate parasitic worms) for oral administration, and is approved in the US and some other countries in a tablet form. A new liquid formulation of ivermectin has been developed to facilitate dosing. This is a single dose, randomised, crossover study in healthy adult male and female volunteers, with doses taken 20 minutes after a standard breakfast. Doses will separated by washout period of at least 14 days. Twenty-one blood samples will be taken from each volunteer over 144 hours in each period. Concentrations of Ivermectin in plasma will be measured using a validated chromatographic assay (LC-MS/MS). Standard pharmacokinetic parameters will be obtained and bioequivalence on the basis of rate and extent of drug absorption will be assessed.