• Renan M Varrique, Gabriela R Lauretti, Julia A Matsumoto, Vera L Lanchote, and Natalia V de Moraes.
• Faculdade de Ciências Farmacêuticas de Ribeirão Preto, USP - Univ. de São Paulo, Ribeirão Preto, Brazil.
• J. Pharm. Pharmacol. 2016 Nov 1; 68 (11): 1351-1358.

ObjectiveTo evaluate the impact of advanced age on rocuronium kinetic disposition in ASA I-III patients undergoing elective surgeries.MethodsYoung adult (20-50 years, n = 15) and elderly patients (65-85 years, n = 14) submitted to surgery under general anaesthesia were investigated. All patients were induced with individual intravenous doses of midazolam, rocuronium, fentanyl and propofol. Rocuronium-induced neuromuscular block was monitored by train of four stimulations of the adductor muscle of the thumb on the ulnar nerve. The pharmacokinetic parameters were calculated by non-compartmental analysis. The relationship between rocuronium plasma concentration and the neuromuscular blockade was described by a sigmoidal Emax model.Key FindingsElderly patients presented decreased Cl (2.1 ml/kg per min vs 2.8 ml/kg per min; P = 0.0123); increased AUC/dose (507.8 μg min/ml (mg/kg) vs 392.2 μg min/ml/(mg/kg); P = 0.0168) and reduced volume of distribution (285.4 ml/kg vs 435.6 ml/kg, P = 0.0434) compared to young adults. The concentrations required to achieve 50% of maximum neuromuscular block (EC50) were similar for young adult (338.8 ng/ml) and elderly (462.7 ng/ml) patients (P > 0.05).ConclusionsElderly patients showed increased AUC/D and reduced total Cl compared to young adult patients due to the age-related reduced renal function. Differences in the PK-PD properties of rocuronium in elderly population are due to changes in drug disposition rather than to alterations in the sensitivity to the drug.© 2016 Royal Pharmaceutical Society.

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