E. Tassonyi et al., PHARMACOKINETICS OF PIPECURONIUM IN INFANTS, CHILDREN AND ADULTS, European journal of drug metabolism and pharmacokinetics, 20(3), 1995, pp. 203-208
In order to explain the reported shorter clinical duration of action o
f cumulative ED(95) of pipecuronium in infants as compared to children
or adults. the pharmacokinetic profiles of pipecuronium were compared
in infants (n = 6; mean age 6.8 months; mean weight 7.3 kg) in childr
en (n = 6: mean age 4.6 years: mean weight 19.2 kg) and in adults (n =
7; mean age 42 years; mean weight 58.2 kg). Equipotent doses (2 x ED(
95)) of pipecuronium were injected i.v. as single bolus and arterial b
lood was sampled for 4-5 h. Pipecuronium was quantified by complex for
mation with [I-125]-labelled rose bengal. Pharmacokinetic parameters w
ere calculated using a two-compartment open model. The median for the
distribution half-life of pipecuronium was 2.54 min (interquartile ran
ge: 1.0-2.5 min) in infants and 2.04 min (0.26-2.04 min) in children;
both were significantly shorter than in adults (5.75 [3.7-9.7] min). T
he plasma clearance of pipecuronium was significantly decreased in inf
ants (1.50 [0.6-1.5] ml.min(-1).kg(-1); P < 0.05) as compared to child
ren and adults (2.27 [0.88-2.27] and 2.45 [1.7-3.2] ml.min(-1).kg(-1),
respectively). The total volume of distribution was similar in all th
ree groups. We conclude that the pharmacokinetic features of pipecuron
ium are age-dependent: differences as compared to adults consisted of
a faster distribution in both infants and children and a slower elimin
ation in infants. The pharmacokinetic profile of pipecuronium does not
explain the faster recovery from neuromuscular blockade in infants as
compared to children. Because of the low total plasma clearance in in
fants, pipecuronium dosage should be carefully monitored to avoid accu
mulation and prolonged paralysis.