When given at a dosage of 10 mg/kg of body weight, diamfenetide was 87% effective in preventing the establishment of F hepatica infections in sheep that were given the drug daily for 14 days and it was 96% effective in sheep that were given the drug for 21 days. Infective cysts (4 doses of 150 each) were given by capsule at 2-day intervals during the first week of medication.

Adult liver flukes were collected from the common bile duct of freshly slaughtered rats 11 - 12 weeks after infection and transferred to Hedon-Fleig media at 37 deg-C. Immature liver flukes were harvested from the liver of rats 4-week post infection; the lier was finely chopped and incubated in Hedon-Fleig media at 37 deg-C. Two antibiotics, 0.006% w/v benzylpenicillin and 0.01% w/v streptomycin sulfate, were also added to the fluke cultures. Exposure of flukes to drug compounds was conducted aerobically at 37 deg-C. The active metabolite of diamphenethide is diamphenathide-amine which was determined to a have a minimum lethal dose of 2 micro-g/mL for 20 hours at 37 deg-C. However, newly excised flukes were more susceptible, disintegrating within 20 hours in 0.5 micro-g/mL. A dose and time-dependent relationship was established wherein adult flukes exposed to 25 micro-g/mL for less than 1 hour, 10 micro-g/ml for 2 h or 5 micro-g/ml for 3 h died after transfer to drug-free medium for a further 20 h. Immature flukes exposed to 2 micro-g/mL for 5 hours showed visible signs of deterioration but survived after transfer to drug-free medium.