An optimal LC-MS/MS method for determination of azithromycin in white blood cells: application to pediatric samples.
BACKGROUND
Studies suggest that particular antimicrobial and anti-inflammatory properties of azithromycin (AZM) can be related to its extensive accumulation in white blood cells (WBCs). However, available methods for determination of AZM in WBCs require large blood volumes unsuited to a pediatric context. Therefore, an LC-MS/MS method was developed for determination of AZM in WBCs.


RESULTS
WBCs were isolated from 500 µl of whole blood by lysing red blood cells. Then, lysis of WBCs was performed with methanol/buffer containing AZM-d3-(13)C as internal standard. After reversed phase LC, detection was performed under multiple reaction monitoring conditions in positive electrospray mode. Linearity ranged from 0.5 to 200 ng per WBC sample. Within-run and overall accuracy and precision ranged from 95.3 to 101.1% and from 1.6 to 4.7%, respectively. All validation parameters fulfilled international requirements.


CONCLUSIONS
This method can be easily performed on small samples and provides reliable data, including in children and neonates.
Department of Pediatric Pharmacology & Pharmacogenetics, Hôpital Robert Debré, APHP, 48 Boulevard Sérurier, 75019 Paris, France.
Tiphaine
T
Legrand
Valery
V
Elie
Sailesh
S
Kotecha
Christophe
C
Junot
Evelyne
E
Jacqz-Aigrain
Alain
A
Pruvost
D000293:Adolescent; D053000:Analytic Sample Preparation Methods; D017963:Azithromycin / Q000097:blood* / Q000302:isolation & purification; D002452:Cell Count; D002648:Child; D002675:Child, Preschool; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007962:Leukocytes / Q000737:chemistry* / Q000166:cytology; D057230:Limit of Detection; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry / Q000379:methods*
D017963:Azithromycin