The effect of site (deltoid or gluteus muscle) of intramuscular administration of anaesthetic drugs on the course of immobilisation in macaque monkeys (Macaca mulatta)

Abstract

The aim of this work was to study the effect of site of intramuscular administration of anaesthetic drugs on the course of immobilisation in macaque monkeys (Macaca mulatta). Twenty macaque monkeys were given medetomidine (25 µg·kg-1) and ketamine (3 mg·kg-1) intramuscularly to the deltoid (n = 10 animals) or gluteus (n = 10 animals) muscles. Behavioural changes, loss of aggressiveness, immobilisation time and cardiorespiratory changes were recorded. The effect of drugs was reversed after 20 min by i.m. administration of atipamezole at the dose of 250 µg·kg-1. Highly significant differences (P < 0.001) were found between groups with gluteal or deltoid administration of drugs on the onset of immobilisation effect (71.3 s and 108.3 s, respectively), and immobilisation time (152.7 s and 254.4 s, respectively). In the gluteus muscle group, the grasp reflex was still present at the beginning of immobilisation and slowly wore off in 15–45 s. The same was valid for muscle tone. There were no differences in cardiorespiratory parameters in any of the groups. Animals of both groups recovered in 3–6 min after atipamezole administration. Administration of drugs to the deltoid muscle resulted in a more rapid onset and increased effect of immobilisation than administration to the gluteus muscle. Both in veterinary and human medicine, injection to the deltoid muscle may be more convenient in all cases, when rapid and more prominent effect is desirable as in premedication before surgery or in emergency medicine. The study is the first to compare the effect of administering drugs to different muscles and the results may improve the practice of intramuscular injections in animals and in humans.