This study was designed to measure total and free bupivacaine (B) after spinal anaesthesia in newborns and to evaluate a possible influence of adrenaline on B absorption. Twenty-two newborns were randomly allocated to receive either plain B (group 1) or adrenaline added to B (group 2) for spinal anaesthesia. A single blood sample was collected ten min after spinal injection. Total B concentration was found 0.31 +/- 0.17 microgram ml-1 in group 1 and 0.25 +/- 0.09 microgram ml-1 in group 2. Bound B concentration was 0.27 +/- 0.17 microgram ml-1 in group 1 and 0.22 +/- 0.09 microgram ml-1 in group 2. No difference was found between the two groups for these parameters. Albumin but not alpha 1-acid-glyco-protein correlated to age and weight, bound B correlated to alpha 1-acid-glyco-protein but not to albumin. Despite the low plasma concentration of binding proteins in newborns, spinal anaesthesia with B does not result in a high level of free drug. Adrenaline does not have any pharmacological advantage in these patients.

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Eight trials comparing the effects of vecuronium in patients with either normal renal function or renal failure were subjected to a meta-analysis. Vecuronium doses were similar in the different trials, identical in the two patient groups of any given trial, and ranged from 0.05 to 0.14 mg.kg-1. Neuromuscular blockade was assessed by TOF or single twitch stimulation, and recorded by either mechanomyography or electromyography. Indices of blockade included onset time (from injection to maximal twitch depression), duration of action (from injection to recovery to 25% of control twitch) and 25-75% recovery index. Statistical analysis used Hedges method: effect size and variance were calculated for each relevant outcome, then the global effect size was estimated by pooling the effect sizes of each trial. Three separate meta-analyses were conducted. No differences were found either in onset time, or in recovery index between the two groups, whereas the duration of action was longer in the renal failure group. It is concluded that renal function is likely involved in the pharmacokinetic parameters of vecuronium.