Pharmacokinetic evaluation of cefoperazone in infants

Physiologically based pharmacokinetic modelling of cefoperazone in paediatrics

AIMS

Cefoperazone is commonly used off-label in the treatment of bacterial meningitis and sepsis in children, and the pharmacokinetic (PK) data are limited in this vulnerable population. The goal of this study was to develop a physiologically based pharmacokinetic (PBPK) model to predict pediatric cefoperazone exposure for rational dosing recommendations.

METHODS

A cefoperazone PBPK model for adults was first constructed using Simcyp V22 simulator. Subsequently, the model was extended to children based on the built in age-dependent physiological parameters, while the drug characteristics remained unchanged. The verified pediatric PBPK model was then utilized to assess the rationality of the common dosing regimens for children at different age groups.

RESULTS

Cefoperazone PBPK model included elimination via biliary excretion, glomerular filtration, and organic anion transporter 3 (OAT3)-mediated tubular secretion. 95.2% of the observed mean concentrations and 100% of the area under the plasma drug concentration-time curve (AUC) and peak concentration (Cmax) in adults were within a twofold range of model mean predictions. Good predictive accuracy was also observed in children, including neonates. 50 mg/kg q12h cefoperazone demonstrated effective target attainment in virtual term neonates (<1 month) when the MIC was ≤1 mg/L, adhering to the stringent PK/PD target of 75% fT > MIC. 37.5 mg/kg q12h cefoperazone achieved the common 50% fT > MIC target for an MIC ≤ 0. 25 mg/L in virtual pediatric patients ranging from 1 month to 18 years of age.

CONCLUSIONS

A pediatric PBPK model was developed for cefoperazone, and it could serve as the basis for deriving rational dosing regimens in children.

Evaluation of evidence for pharmacokinetics-pharmacodynamics-based dose optimization of antimicrobials for treating Gram-negative infections in neonates

BACKGROUND & OBJECTIVES

Neonates present a special subgroup of population in whom optimization of antimicrobial dosing can be particularly challenging. Gram-negative infections are common in neonates, and inpatient treatment along with critical care is needed for the management of these infections. Dosing recommendations are often extrapolated from evidence generated in older patient populations. This systematic review was done to identify the knowledge gaps in the pharmacokinetics-pharmacodynamics (PK-PD)-based optimized dosing schedule for parenteral antimicrobials for Gram-negative neonatal infections.

METHODS

Relevant research questions were identified. An extensive electronic and manual search methodology was used. Potentially eligible articles were screened for eligibility. The relevant data were extracted independently in a pre-specified data extraction form. Pooling of data was planned.

RESULTS

Of the 340 records screened, 24 studies were included for data extraction and incorporation in the review [carbapenems - imipenem and meropenem (n=7); aminoglycosides - amikacin and gentamicin (n=9); piperacillin-tazobactam (n=2); quinolones (n=2); third- and fourth-generation cephalosporins (n=4) and colistin nil]. For each of the drug categories, the information for all the questions that the review sought to answer was incomplete. There was a wide variability in the covariates assessed, and pooling of results could not be undertaken.

INTERPRETATION & CONCLUSIONS

There is a wide knowledge gap for determining the doses of antimicrobials used for Gram-negative infections in neonates. A different profile of newborns in the developing countries could affect the disposition of antimicrobials for Gram negative infections, necessitating the generation of PK-PD data of antimicrobials in neonates from developing countries. Further, guidelines for treatment of neonatal conditions may incorporate the evidence-based PK-PD-guided dosing regimens.

Clinical Pharmacokinetics of Penicillins, Cephalosporins and Aminoglycosides in the Neonate: A Review

Bacterial infections are common in the neonates and are a major cause of morbidity and mortality. Sixty percent of preterm infants admitted to neonatal intensive care units received at least one antibiotic during the first week of life. Penicillins, aminoglycosides and cephalosporins comprised 53, 43 and 16%, respectively. Kinetic parameters such as the half-life (t1/2), clearance (Cl), and volume of distribution (Vd) change with development, so the kinetics of penicillins, cephalosporins and aminoglycosides need to be studied in order to optimise therapy with these drugs. The aim of this study is to review the pharmacokinetics of penicillins, cephalosporins and aminoglycosides in the neonate in a single article in order to provide a critical analysis of the literature and thus provide a useful tool in the hands of physicians. The bibliographic search was performed electronically using PubMed, as the search engine, until February 2nd, 2010. Medline search terms were as follows: pharmacokinetics AND (penicillins OR cephalosporins OR aminoglycosides) AND infant, newborn, limiting to humans. Penicillins, cephalosporins and aminoglycosides are fairly water soluble and are mainly eliminated by the kidneys. The maturation of the kidneys governs the pharmacokinetics of penicillins, cephalosporins and aminoglycosides in the neonate. The renal excretory function is reduced in preterms compared to term infants and Cl of these drugs is reduced in premature infants. Gestational and postnatal ages are important factors in the maturation of the neonate and, as these ages proceed, Cl of penicillins, cephalosporins and aminoglycosides increases. Cl and t1/2 are influenced by development and this must be taken into consideration when planning a dosage regimen with these drugs. More pharmacokinetic studies are required to ensure that the dose recommended for the treatment of sepsis in the neonate is evidence based.