Pharmacokinetics of prilocaine in intravenous regional anaesthesia

Abstract

To determine the acute pharma‐cokinetics of prilocaine in intravenous regional anaesthesia (IVRA), plasma prilocaine levels before and after tourniquet release were measured for sixteen patients (including six children) with forearm fractures. A dose of 2.5mg/kg was used with a minimum cuff occlusion time of 20 minutes. No patients had detectable drug levels prior to tourniquet release. Peak drug concentrations were reached within 10 minutes of tourniquet release in all patients. Average peak drug concentration was 1.23mcg/ml. By 30 minutes, drug levels had reached an average of 0.34mcg/ml (range <0.3–0.6mcg/ml). The pharmacokinetic curves of the children were similar in profile to the adults, with analysis of variance failing to demonstrate a significant difference between curves. In no patients did prilocaine reach toxic levels. These results show that prilocaine used at a dose of 2.5 mg/kg is safe and that an observation period of 30 minutes following IVRA is adequate. IVRA does not appear to be contraindicated in children.

Pharmacokinetics of prilocaine in intravenous regional anaesthesia

“…Outpatient management of selected forearm fractures is an extension of this concept. Our study demonstrates that the pharmacokinetics of prilocaine in children resembles that of adults and allows for the logical extension of outpatient management of selected forearm fractures to children 2 . It does not however exclude the possible sensitivity of some children and adults so that clinical vigilance is always as required.…”

Intravenous regional anaesthesia

“…Without wishing to detract from the merit of the scientific research involved in Smyth and Hendrie's article 1 on intravenous regional anaesthesia (IVRA), I am concerned by their conclusion regarding IVRA not being contraindicated in children. A conclusion that there is no pharmacokinetic contraindication would have been more reasonable.…”