Korean Journal of Anesthesiology



Experimental Research Article
Korean J Anesthesiol. 1998;34(4):686-693.
DOI: https://doi.org/10.4097/kjae.1998.34.4.686
Neuromuscular Interactions between Mivacurium and Rocuronium in Rabbits.
Young Joo Park, Hee Koo Yoo, Kyo Sang Kim, Jae Hang Shim
1Department of Anesthesiology, Hanyang University, College of Medicine, Seoul, Korea.
2Department of Anesthesiology, College of Dentistry, Kangnung National University, Kangnung, Korea.
Mivacurium has a considerably shorter duration of action than any other currently used nondepolarizing agent. Rocuronium, on the other hand, has a brief onset but an intermediate duration of action. The current study was undertaken to characterize the interaction between mivacurium and rocuronium in rabbits.
In the first study, the dose-response relations of mivacurium, rocuronium and their combination were studied in thirty rabbits during thiopental anesthesia. Rabbits, randomly assigned to three groups (n=10), received mivacurium 10, 20, or 30 microgram/kg; rocuronium 50, 70, or 90 microgram/kg; or an equieffective combination of both drugs (0.3 ED50 mivacurium 0.3 ED50 rocuronium; 0.5 ED50 mivacurium 0.5 ED50 rocuronium; or 0.7 ED50 mivacurium 0.7 ED50 rocuronium, where ED50 is the dose producing 50% depression of the twitch height). In the second study, twenty rabbits were randomly allocated to two groups (n=10) to receive mivacurium 0.18 mg/kg or rocuronium 0.6 mg/kg. When the twitch height recovered to 25%, each rabbit received mivacurium 16.4 microgram/kg.
The calculated ED95 and ED50 for mivacurium were 29.1 4.2 (mean SD) and 16.4 3.3 microgram/kg, respectively. Corresponding rocuronium was 95.1 6.7 and 61.5 5.3 microgram/kg, respectively. The interaction between mivacurium and rocuronium was found to be synergistic. The measured ED50 of the mixture was only 54% of the predicted value assuming a purely additive interaction. In the second study, the times after mivacurium until 95% in mivacurium and rocuronium group were 18.1 4.6 min and 37.7 5.7 min, respectively (p<0.0001).
The combination of mivacurium and rocuronium is synergistic interaction and after rocuronium induced neuromuscular block, mivacurium becomes a longer acting agent than the shorter agent.

Keywords :Pharmacodynamics: interactions; potency;Animals: rabbits;Neuromuscular relaxants: mivacurium; rocuronium.

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