Synergism between rocuronium and cisatracurium: comparison of the Minto and Greco interaction models

Abstract

BackgroundThis study was conducted to investigate the pharmacodynamic interaction between rocuronium and cisatracurium using the response surface model, which is not subject to the limitations of traditional isobolographic analysis.MethodsOne hundred and twenty patients were randomly allocated to receive one of the fifteen predefined combinations of rocuronium and cisatracurium. To study single drugs, cisatracurium 0.2, 0.15, or 0.1 mg/kg or rocuronium 0.8, 0.6 or 0.4 mg/kg doses were administered alone. To study the pharmacodynamic interaction, drugs were applied in three types of combination ratio, i.e., half dose of each drug alone, 75% of each single dose of rocuronium and 25% of each single dose of cisatracurium, and vice versa. Train-of-four (TOF) ratio and T1% (first twitch of the TOF presented as percentage compared to the initial T1) were used as pharmacodynamic endpoints, and the Greco and Minto models were used as surface interaction models.ResultsThe interaction term α of the Greco model for TOF ratio and T1% measurements showed synergism with values of 0.977 and 1.12, respectively. Application of the Minto model resulted in U50 (θ) values (normalized unit of concentration that produces 50% of the maximal effect in the 0 < θ < 1 region) less than 1 for both TOF ratio and T1% measurements, indicating that rocuronium and cisatracurium exhibit synergism.ConclusionsResponse surface modeling of the interaction between rocuronium and cisatracurium, based on considerations of their effects on muscle relaxation as measured by TOF ratio and T1%, indicated that the two drugs show considerable synergism.

Clinical Pharmacology of Rocuronium in Infants and Children

“…Rocuronium interacts with drugs [18][19][20][21][22][23]. The co-administration of rocuronium with cisatracurium results in a synergistic effect [18], rocuronium inhibits the formation-rate of temazepam and desmethyldiazepam [19], magnesium potentiates the neuromuscular effect of rocuronium [20], the interaction between rocuronium and vecuronium, pipecuronium or pancuronium is additive [21], anticonvulsants drugs reduce the duration of rocuronium effect [22], and phenytoin augments the neuromuscular block produced by rocuronium [23]. The treatment of infants and children with rocuronium has been studied [24][25][26][27][28].…”

“…The co-administration of rocuronium with cisatracurium results in a synergic effect [18]. Rocuronium inhibits the formation-rate of temazepam and desmethyldiazepam by 20% and 15%, respectively, in human liver microsomes [19].…”