Pharmacokinetics and pharmacodynamks of chloroprocaine with or without epinephrine for epidural blockade / 中华麻醉学杂志

ABSTRACT

Objective To determine the pharmacokinetics and pharmacodynamics of chloroprocaine with or without epinephrine for epidural blockade. Methods Twenty ASA physical status Ⅰ or Ⅱ patients of both sexes aged 37-55 yrs weighing 45-80 kg undergoing elective lower abdominal surgery were randomly divided into 2 groups (n = 10 each) group C chloroprocaine without epinephrine and group CE chloroprocaine with epinephrine. The epidural catheter was inserted into epidural space at T12-L4 and advanced toward head for about 4 cm. After correct epidural placement was confirmed,3% chloroprocaine 6 mg?kg-1 with or without 1200 000 epinephrine was injected into epidural space over 2 min. Onset time of analgesia , motor blockade and degree of motor blockade at 20 min after epidural injection (Bromage scale 0 = no motor block, 3 = unable to flex hip, knee and ankle) were recorded. Blood samples were taken from radial artery before and at 3, 6, 9, 11, 13, 15, 17, 20, 30, 45, 60, 90 min after epidural injection for determination of plasma chloroprocaine concentration by HPLC. Results The two groups were comparable with respect to demographic data. There were no significant differences in the pharmokinetics and pharmacodynamics of chloroprocaine between the two groups. The Cmax was (0.491?0.47) mg?L-1 and (0.32?0.22) mg?L-1; The Tmax was (8?3) min and (9?4) min; the AUC was (10?6) ?g?min?ml-1 and (7?4) ?g?min?ml-1;the K was 0.32?0.21 min-1 and 0.36?0.32 min-1 in group C and CE respectively. Conclusion Epinephrine 1200 000 does not affect the pharmacokinetics and pharmacodynamics of 3 % chloroprocaine for epidural block.