Effect of Metocurine Iodide on Neuromuscular Blockade and Hemodynamics

Lee, Kyoung Min; Nam, Yong Taek; Park, Kwang Won; Kim, Ji Soo; Park, Tae In

Abstract

Among nondepolarizing neuromuscular blocking agents, d-tubocurarine may cause blood pressure reduction due to ganglionic blockade and histamine release, while pancuronium and gallamine are associated with vagal blockade and heart rate acceleration. Metocurine, as a trimethylated derivative of d-tubocurarine synthesized by King in 1935, is known to have relatively long duration of action and produces little change in cardiovascular system. Despite its relative lack of cardiovascular effects, the accumulation of data with regard to human neuromus- cular pharmacology and the clinical use has been scant. One hundred and nine adult patients of either sex were anesthetized with thiopental sodium and 50% nitrous oxide with 1.5-2.5% enflurane. For evaluation of neuromuscular blocking effect of metocurine, train-of-four stimulation (2.0 Hz for 2 seconds) was applied at the wrist along the ulnar nerve distribution and the response was measured via ABM Datex. Systolic, diastolic blood pressure and heart rate were recorded continuously after administration of metocurine, d-tubocurarine or pancuronium. All data were analized by ANOVA, Scheffe test. The results are follows : 1) The mean onset times of metocurine 0.1, 0.2, 0.3 mg/kg groups were 119.5+/-40.0, 120.9+/-61.1, 84.8+/-61,1 seconds and the mean durations were 75.1+/-37.6, 104.9+/-42.1, 131.0+/-42.5 minutes respectively. 2) Single-bolus dose of metocurine 0.1, 0.2, and 0.3 mg/kg did not cause significant cardiovascular changes from the control values, but d-tubocurarine 0.3 mg/kg decreased mean systolic blood pressure significantly from 116.6+/-15.7 to 99.0+/-10.9 mmHg 2 minutes after injection. 3) Systolic blood pressures of metocurine 0.2 mg/kg (107.2+/-11.7 mmHg) and d-tubocurarine 0.3 mg/ kg (100.4+/-12.9 mmHg) were significantly different from that of pancuronivm 0.06 mg/kg (127.8+/-16. 0 mmHg) after 1 minute, and 2 minutes after injection, systolic blood pressure of metocurine 0.2 mg/ kg (110.2+/-14.3 mmHg) and d-tubocurarine 0.3 mg/kg (99.0+/-10.9 mmHg) were different from that of pancuronium 0.06 mg/kg (125.3+13.1 mmHg). Five minutes after injection, systolic pressure of d- tubocurarine 0.3mg/kg group (101.110.2mmHg) was significantly different from that of pancur-onium 0.06 mg/kg group (118.7+/-11.0 mmHg). 4) Diastolic blood pressure of d-tubocurarine 0.3 mg/kg (63.4+/-12.9 mmHg) was significantly differ- ent from that of pancuronium 0.06mg/kg (84.2+/-13.3mmHg) after 1 minute, and 2 minutes after injection, diastolic blood pressure or d-tubocurarine 0.3 mg/kg (65.4+/-11.3 mmHg) was different from that of pancuronium 0.06mg/kg (83.1+/-11.6mmHg). There was no significant difference among the groups with respect to heart rate. In summary, metocurine has relatively rapid onset and long duration of action, and used in a dose sufficient to provide surgical relaxation, it produces little change in cardiovascular system in contrast to d-tubocurarine or pancuronium. 1t is therefore suggested that metocurine may be recommended as a muscle relaxant for patients having cardiovascular disease.