Betydelsen av prokainets nedbrytning i plasma vid penicillinchock hos häst
The use of intramuscular injections of procaine penicillin G (bensylpenicillin procaine) in the horse is now and then associated with acute adverse reactions (penicillin-chock). The etiology is not yet clearly understood, but the theories are several. One possibility is that it can be caused by procaine toxicity. Procaine penicillin G is a salt which is quickly dissolved in plasma. Procaine is then metabolized by plasmaesterases to non-toxic metabolites, p-aminobenzoic acid (PABA) and diethylaminoethanol. The purpose of this study was to investigate if there are any differences in the esterase activity in plasma between horses that had suffered from adverse reactions and a group of horses that had no reactions, following intramuscular injection of procaine penicillin G. Furthermore the rate of hydrolysis of procaine was investigated in a normal, healthy group of horses. In this group the possible variation of the procaine hydrolysis during a period of twenty-four hours was also examined. Procaine was incubated in horse plasma and the amount of PABA formed was measured by HPLC analysis. The results showed a tendency that the horses suffering from adverse reactions had a lower activity of procaine hydrolysis compared to the control group. The difference was not statistically significant at a level of 95% (the p-value was 0,076). The study also showed that there is a great individual variation in esterase activity in a normal population of horses. Furthermore there is no marked variation in esterase activity during a period of twenty-four hours.