Pharmacokinetics and Pharmacodynamics of Vecuronium in the Obese Surgical Patient

Abstract

The effect of obesity on the disposition and action of vecuronium was studied in 14 surgical patients. After induction of anesthesia with thiopental and maintenance of anesthesia by inhalation of nitrous oxide and halothane, seven obese patients (93.4 +/- 13.9 kg, 166% +/- 30% of ideal body weight, mean +/- SD) and seven control patients (60.9 +/- 12.3 kg, 93% +/- 6% of ideal body weight) received 0.1 mg/kg of vecuronium. Plasma arterial concentrations of muscle relaxant were determined at 1, 3, 5, 10, 15, 20, 30, 45, 60, 90, 120, 150, 180, 210, 240, 300, and 360 min by a spectrofluorometric method. Simultaneously, neuromuscular blockade was assessed by stimulation of the ulnar nerve and quantification of thumb adductor response. Times to 50% recovery of twitch were longer in the obese than in the control patients (75 +/- 8 versus 46 +/- 8 min) as were 5%-25% recovery times (14.9 +/- 4.0 versus 10.0 +/- 1.7 min) and 25%-75% recovery times (38.4 +/- 13.8 versus 16.7 +/- 10.3 min). However, vecuronium pharmacokinetics were similar for both groups. When the data were calculated on the basis of ideal body weight (IBW) for obese and control patients, total volume of distribution (791 +/- 303 versus 919 +/- 360 mL/kg IBW), plasma clearance (4.65 +/- 0.89 versus 5.02 +/- 1.13 mL.min-1.kg IBW-1), and elimination half-life (119 +/- 43 versus 133 +/- 57 min) were not different between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia in the obese patient: Pharmacokinetic considerations

“…In the same study, the authors also observed that although atracurium concentrations were higher in the obese than nonobese patients, there was no difference between the 2 groups in the time of recovery from neuromuscular blockade. Schwartz et al [91] evaluated the pharmacokinetic and pharmacodynamic profiles of vecuronium administered to 7 obese and 7 normal-weight subjects and showed that when the data were calculated on the basis of IBW, total volume of distribution (791 F 303 vs 919 F 360 mL/kg), plasma clearance [4.65 zF 0.89 vs 5.02 F 1.13 mL/(mind kg)], and elimination half-life (119 F 43 vs 133 F 57 minutes) did not differ between obese and nonobese patients. Nonetheless, the authors reported a difference in duration of action of vecuronium in obese patients compared with nonobese subjects.…”

Optimum priming dose of vecuronium for tracheal intubation

“…In obese patients, the speed of onset was expected to be faster because of a smaller distribution volume per body weight [14]. The multiple regression analysis in this study demonstrated that this prediction was correct, [8], and the priming technique.…”

Vecuronium Requirement By Continuous Infusion Technique In Adult Patients During Fentanyl Nitrous Oxide – Oxygen Anesthesia.

“…AE Schwartz, et al 22 proved that time to recovery from neuromuscular blockade was longer in obese patients (93.4 + 13.9 kg) as opposed to non-obese patients (60.9 + 12.3 kg).Cynthia A Lien, et al 23 and De Almeida Mc, et al 24 concluded that an anesthetist should expect the action of vecuronium to be prolonged in elderly surgical patients. The altered pharmacokinetics and age related changes in renal and hepatic function prolonged the recovery time.…”