Intramuscular administration of atropine in the rat: jet spray versus conventional needle injection

The characteristics of atropine plasma levels after jet spray injection were compared to those after conventional needle injection (i.m.) in 12 male rats, six per group. Blood samples were sequentially collected from the tip of the tail over a 7h period. Injection of atropine sulfate (8.0 mg kg-1) using the jet spray resulted in mean peak plasma levels of 650 ng ml-1 (95 per cent C.I. = 90) compared to 488 ng mg-1 (95 per cent C.I. = 64) using a conventional needle. Times to reach maximum concentration were 30 min (95 per cent C.I. = 12) and 58 min (95 per cent C.I. = 6) for the jet spray and needle, respectively. Histopathologic examination (5 days post-injection) of target muscle showed that minimal fiber damage resulted from using the low pressure setting on the jet spray. The results suggest that the jet spray may offer a means of increasing the antidotal benefit over that achieved with conventional techniques using presently available therapeutic formulations for acetylcholinesterase poisoning.