title: Effect of pharmacokinetic sampling methods on aminoglycoside dosing in critically ill surgery patients.
abstract: We compared pharmacokinetic parameters derived from three aminoglycoside serum concentration sampling methods and evaluated their effects on recommended aminoglycoside dosing regimens in 60 critically ill surgery patients. Patients had presumed or documented gram-negative sepsis, and had at least 4 aminoglycoside serum concentrations measured. We used a one-compartment model for peak and trough, 3-point series, and 4-point series sampling methods. Dosing regimens were calculated for each patient based on values derived from each method. We found differences in regimens for nearly 50% of patients if either 4- or 3-point series sampling was used to calculate the recommended dosage rather than peak and trough sampling. However, the 3-point method required a clinically significant change in regimen in only 12% of patients compared with 4-point sampling. The variability of all values derived from 3-point sampling were well accounted for by the 4-point method (r2 > 0.80). In addition, we noted significantly greater relative precision for 3-point sampling than peak and trough sampling for estimates of clearance, elimination rate, recommended daily dosage, and recommended dosing frequency. We recommend three optimally timed samples be drawn instead of peak and trough levels in dosing aminoglycosides in critically ill surgery patients.
authors.affiliation: College of Pharmacy, University of Minnesota, Minneapolis, USA.
authors.forename: H J
authors.initials: HJ
authors.lastname: Mann
authors.forename: E T
authors.initials: ET
authors.lastname: Wittbrodt
authors.forename: A A
authors.initials: AA
authors.lastname: Baghaie
authors.forename: F B
authors.initials: FB
authors.lastname: Cerra
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D001800:Blood Specimen Collection / Q000379:methods*; D016638:Critical Illness / Q000628:therapy; D003428:Cross Infection / Q000382:microbiology; D003627:Data Interpretation, Statistical; D004305:Dose-Response Relationship, Drug; D005260:Female; D005839:Gentamicins / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D011183:Postoperative Complications / Q000097:blood / Q000382:microbiology / Q000601:surgery*; D012016:Reference Values; D018401:Sample Size; D013530:Surgical Wound Infection / Q000097:blood / Q000382:microbiology; D013997:Time Factors; D014031:Tobramycin / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins; D014031:Tobramycin