a comparison on the effects of erythromycin and ivermectin on abomasal emptying in calves

a comparative study on the effect of erythromycin and ivermectin on abomasal emptying in holstein-friesian calves motilides namely erythromycin have a great ability to increase abomasal emptying rate. the aim of this study was to evaluate the abomasal emptying rate in calves receiving either erythromycin or ivermectin. five male holstein-friesian calves were given each of the following 4 treatments in random order: control, 2 ml of 0.9% nacl im; erythromycin, 8.8 mg/kg im; ivermectin, 200ug/kg iv. abomasal emptying rate was assessed by acetaminophen absorption. calves were fed 2 l of cow抯 milk containing acetaminophen (50 mg/kg body weight) 30 min after each treatment was administered and jugular venous blood samples were obtained periodically after suckling. the maximum observed plasma concentration (actual cmax) and time of maximum observed plasma concentration (actual tmax) were obtained from a plot of the plasma acetaminophen concentration versus time data. non linear regression analysis was used to model the plasma acetaminophen concentration-time relationship and calculate model cmax and model tmax. the results showed that administration of ivermectin could increase the abomasal emptying rate but to a lesser extent compared to erythromycin. also the increase in plasma glucose after administration of ivermectin was comparable to erythromycin.the study also revealed that ivermectin unlike other motilides in spite of lacking a dimethylamino group could affect the gastrointestinal motility. this might imply that ivermectin exerts its effect via a different route other than affecting motilin receptors, or may question necessariness of dimethy amino group for the promotility effects.