Original Research
Tuesday, November 14, 2023
08:30 AM–10:00 AM
Abstract
Introduction:
The objective of this study was to evaluate the population pharmacokinetics and pharmacodynamics of cephalexin in hospitalized patients with high body weight
Research Question or Hypothesis:
Does morbidly obese patients require larger doses of cephalexin compared to non-morbidly-obese patients?
Study Design:
Prospective pharmacokinetic study
Methods:
Hospitalized patients expected to receive cephalexin 1 g q6h for treatment of suspected or documented infections were enrolled. Morbid obesity and non-morbid-obesity were defined as a body mass index (BMI) of = 40 kg/m2 and < 40 kg/m2, respectively. Total and unbound serum cephalexin concentration-time data obtained from serial blood samples were analyzed simultaneously by population pharmacokinetic modeling with allometric scaling using NONMEM. Probability of target attainment (PTA) was calculated for various dosing regimens through Monte Carlo simulations based on the pharmacokinetic/pharmacodynamic target of fT>MIC = 40% and 60%.
Results:
Overall, 19 patients (9 with a BMI of = 40 kg/m2 and 10 with a BMI < 40 kg/m2) were included in this study. A one-compartment model with linear protein binding and allometric scaling of systemic clearance using ideal body weight best characterized both total and unbound concentration-time data. Serum creatinine concentration was the only covariate significantly associated with systemic clearance (P < 0.05). Based on unbound concentration-time profiles using fT>MIC = 40%, all simulated dosing regimens achieved PTA > 90% at MICs = 2 mg/L; at an MIC of 4 mg/L, dosing regimens = 1 g q8h attained PTA > 90% in both patient groups. At fT>MIC = 60%, cephalexin dosages = 1 g q6h attained PTA > 90% at MICs at an MIC of 4 mg/L in both patient groups.
Conclusion:
The pharmacokinetics of cephalexin is comparable between morbidly obese and non-morbidly-obese patient groups. Cephalexin dosage adjustments based solely on body weight are unnecessary.
Presenting Author
Hyeon Ji Kim Pharm.D. Candidateㄹㄹ
Authors
Maureen Campion Pharm.D.
Purdue University College of Pharmacy
Michael B. Kays Pharm.D.
Purdue University College of Pharmacy
Alicia M. Gesenhues Pharm.D.
James L. Winkle College of Pharmacy, Division of Pharmacy Practice and Administrative Sciences, University of Cincinnati Academi
Daniel P. Healy Pharm.D.
Division of Pharmacy Practice and Administrative Sciences, James L. Winkle College of Pharmacy, University of Cincinnati Academi
Julia Jeffery Pharm.D.
James L. Winkle College of Pharmacy, Division of Pharmacy Practice and Administrative Sciences, University of Cincinnati Academi
Timothy Murrey Pharm.D.
OSF St. Anthony Medical Center
S. Christian Cheatam Pharm.D.
Department of Pharmacy, St. Francis Hospital
Eun Kyoung Chung Pharm.D., Ph.D.
Kyung Hee University
Sara Utley Pharm.D.
Andrea H. Stock Pharm.D.
Franciscan St. Francis Health, Department of Pharmacy