Concentration of bupivacaine in arterial and venous plasma after epidural anaesthesia in man and after intramuscular administration in dog.

The arteriovenous concentration difference of bupivacaine in plasma after epidural injection in man and after intramuscular injection in dog was studied. In man, arterial concentration was higher than peripheral venous ocncentration during an initial period of about 30 min, after which time period venous and arterial concentrations became fairly similar. Comparable results were obtained in the animal experiments. In addition, the experiments in dog indicated that the concentration of bupivacaine was fairly similar in central venous plasma and arterial plasma, but higher than the peripheral venous plasma concentration. These factors have to be taken into consideration when toxicological studies of local anaesthetic drugs are made.