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. 2024;16(16):873-881.
doi: 10.1080/17576180.2024.2377912. Epub 2024 Jul 29.

Can capillary microsampling facilitate a clinical pharmacokinetics study of cefazolin in critically ill children?

Tavey Dorofaeff  1   2 , Yarmarly Guerra Valero  1 , Mark G Coulthard  2   3 , Steven C Wallis  1 , Mark D Chatfield  1 , Paula Lister  4 , Jeffrey Lipman  1   5   6   7 , Jason A Roberts  1   5   7   8 , Suzanne L Parker  1
Affiliations

Can capillary microsampling facilitate a clinical pharmacokinetics study of cefazolin in critically ill children?

Tavey Dorofaeff et al. Bioanalysis. 2024.

Abstract

Aim: Pharmacokinetic studies in children are limited, in part due to challenges in blood sampling. We compare the use of capillary microsampling and conventional sampling techniques in pediatric patients to show results that can be used in the pharmacokinetic analysis of Cefazolin.Patients & Methods: Paired blood samples (n = 48) were collected from 12 patients (median age/weight 49 months/18 kg).Results: The United States Federal Drug Administration incurred sample reanalysis acceptance criteria was used and identified 79% of paired samples achieved a difference of less than 20% in magnitude with a capillary microsampling bias of -10% (SD 20%). With exclusion of PK outliers, this rose to 88%.Conclusion: Capillary microsampling is reliable, meets acceptance criteria and can be used in pharmacokinetic studies.ACTRN: 12618001469202.

Keywords: antimicrobials; cefazolin; children; microsampling; pediatric; pharmacokinetics.

Plain language summary

What is this article about? This study assesses a novel method of blood sample collection (capillary microsampling) for the analysis of a common antibiotic, cefazolin. In this study, we compare the results from samples collected using this method to blood tests taken in the traditional way.Capillary microsampling collects a very small volume of blood (about a drop of blood or 0.05 ml) taken from a skin prick and collected in a capillary tube. Traditional blood sampling collects a larger volume of blood (typically from 1 to 3 ml) taken from an artery or a vein. In this study, the patients (10 male and 2 female) had a mean age of 49 months and a mean weight of 18 kg. The amount of cefazolin in the blood samples were analyzed using the same methodology and results compared with assess the variability and reliability of the capillary microsampling method.What were the results? The results showed that difference of the two sample types is within the accepted criteria of the United States Federal Drug Administration and the European Medicines Agency, meaning the results are reliable.What do the results of the study mean? Blood samples for cefazolin can be small and easily obtained from a skin prick as a capillary microsample and can give reliable results. This greatly aids the ability to study the metabolism of cefazolin in children, particularly those that are not able to give a large amount of blood.

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Conflict of interest statement

The authors have no competing interests or relevant affiliations with any organization or entity with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, stock ownership or options and expert testimony.

Figures

Figure 1.
Figure 1.
Cefazolin plasma concentration-time profiles for all patients for capillary microsampling (triangle) and conventional sampling (circle). ‘Conv’ denotes a conventional phelobotomy draw from an arterial or intravenous line. ‘CMS’ denotes a capillary microsampling sample.
Figure 2.
Figure 2.
Bland-Altman plot comparing cefazolin (total) concentrations obtained by capillary microsampling (CMS) from critically ill pediatric patients and those obtained by conventional sampling; the US Food and Drug Administration acceptance criteria for an incurred sample reanalysis test is shown as the grey shaded area, where >67% of data should lie. Percentage difference was calculated as (CMS - conventional)/((CMS + conventional)/2). CMS: Capillary microsampling; LLoA: Lower level of agreement; ULoA: Upper level of agreement.
Figure 3.
Figure 3.
Surface adhesion study for cefazolin in a capillary microsample, with loss of cefazolin, when compared with bulk plasma samples, prepared at concentrations of 1, 2 and 5 mg/l.
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