STELLATE GANGLION BLOCKADE - PHARMACOKINETICS OF LIDOCAINE WITH AND WITHOUT EPINEPHRINE

In order to study the effect of epinephrine on the pharmacokinetics of lidocaine injected for stellate ganglion blockade. 6 patients free of hepatic or renal disease received 1.5 mg/kg of 1% lidocaine, with or without 1/200,000 epinephrine, injected via the anterior paratracheal approach. Using a crossover study design. each patient was investigate d twice at least 4 days apart in a double-blind randomised manner. Ven ous blood samples were collected over 8 hours and plasma lidocaine con centrations were measured using gas liquid chromatography. There was n o difference in time to block onset nor in quality of pain relief betw een the two solutions. No adverse events were observed in either group . The maximum concentration was significantly lower and the lime to ma ximum concentration significantly delayed when epinephrine-containing solutions were used. In addition, the mean residence time was signific antly longer when epinephrine was used. However, the difference in the elimination half-life was not statistically significant between the t wo treatment groups. It is concluded that epinephrine decreases the ra te of absorption of lidocaine when injected for stellate ganglion bloc kade.