Pharmacokinetics of remifentanil in anesthetized pediatric patients undergoing elective surgery or diagnostic procedures

Ak. Ross et al., Pharmacokinetics of remifentanil in anesthetized pediatric patients undergoing elective surgery or diagnostic procedures, ANESTH ANAL, 93(6), 2001, pp. 1393-1401
Citations number
Categorie Soggetti
Aneshtesia & Intensive Care","Medical Research Diagnosis & Treatment
Journal title
ISSN journal
0003-2999 → ACNP
Year of publication
1393 - 1401
SICI code
Remifentanil hydrochloride is an ultra-short-acting opioid that undergoes r apid metabolism by tissue and plasma esterases. We aimed to characterize th e pharmacokinetics and determine the hemodynamic profile of remifentanil af ter a single-bolus dose in children aged 0 to 18 yr. Forty-two children und ergoing elective surgical procedures received remifentanil 5 mug/kg infused over 1 min. Patients were divided into age groups as follows: young infant s (less than or equal to2 mo), older infants (>2 mo to <2 yr), young childr en (2 to <7 yr), older children (7 to < 13 yr), adolescents (13 to < 16 yr) , and young adults (16 to < 18 yr). Arterial blood samples were collected a nd analyzed by mass spectroscopy to determine remifentanil pharmacokinetic profiles. Hemodynamic measurements for remifentanil's effect were made afte r the infusion. Methods of statistical analysis included analysis of varian ce and linear regression, with significance at P less than or equal to 0.05 . Complete remifentanil pharmacokinetic data were obtained from 34 patients . The volume of distribution was largest in the infants <2 mo (mean, 452 mL /kg) and decreased to means of 223 to 308 mL/kg in the older patients. Ther e was a more rapid clearance in the infants <2 mo of age (90 mL . kg(-1) . min(-2)) and infants 2 mo to 2 yr (92 mL . kg(-1) . min(-1)) than in the ot her groups (means, 46 to 76 mL . kg(-1) . min(-1)). The half-life was simil ar in all age groups, with means of 3.4 to 5.7 min. Seven subjects (17%) de veloped hypotension related to the remifentanil bolus. Remifentanil showed an extremely rapid elimination similar to that in adults. The fast clearanc e rates observed in neonates and infants, as well as the lack of age-relate d changes in half-life, are in sharp contrast to the pharmacokinetic profil e of other opioids. Remifentanil in a bolus dose of 5 mug/kg may cause hypo tension in anesthetized children.