What drives prolonged recovery in older patients after rocuronium exposure?

Older patients experience a slightly longer recovery time than their younger counterparts following administration of general anaesthesia, which is caused by an age-dependent increase in tissue uptake, a recent study has shown.

"However, a priori dose adjustments for rocuronium in older patients are not feasible, since age contribution is overshadowed by the overall variability in the recovery time,” the researchers said.

In this study, researchers developed a nonlinear mixed-effect model for rocuronium in patients undergoing general anaesthesia using doses of 0.3–1.2 mg/kg. They assessed plasma concentrations and the neuromuscular block (train of four ratio) up to 6 h after dosing.

The authors also examined the influence of age, BMI, renal function, and sex on pharmacokinetics (PK) and pharmacodynamics (PD). PK and PD were described using a two-compartment model with linear elimination and an indirect sigmoid I-max model. Simulations were used to predict recovery time.

The transfer rate into the periphery increased with age. Following single bolus administrations of doses ≥0.7 mg/kg, the predicted recovery time took slightly longer in older patients aged 85 years than younger adults aged 25 years (median 2.8 vs 2.5 h).

“Residual neuromuscular blockade (RNB) commonly occurs when using neuromuscular blockers and increases the risk for pulmonary complications, such as airway obstruction and severe hypoxemia, in extubated patients,” the researchers said. “Rocuronium exhibits a high variability in recovery time, contributing to an increased risk for RNB."