Chronokinetic study of cefalexin in postprandial and fasting volunteers

Abstract

Few researches were conducted on the circadian variation of β-lactam antibiotics in humans. The aim of the present study was to determine whether circadian variation of cefalexin pharmacokinetics exists in postprandial or fasting male volunteers. Cefalexin was given orally to subjects under postprandial conditions or after an 8-h fast, at 08:00 or 20:00 h. In experiment 1, after the oral dose under postprandial conditions, time-dependent changes in cephalexin pharmacokinetics were significant. The elimination half-life (t _1/2) was prolonged obviously and thepeak serum concentration (C _max) was higher after the 20:00 h compared to the 08:00 h administration. However, in experiment 2, no significant differences were found in the main pharmacokinetic parameters of cephalexin administered at two occasions after fasting. It is concluded that in this study, time of administration may affect the pharmacokinetics of cephalexin under the postprandial condition, and fasting may suppress the diurnal variations in cefalexin pharmacokinetics.

Keywords:

• β-lactam antibiotics
• cephalexin
• chronokinetics
• pharmacokinetics
• human

Acknowledgements

Particular thanks to the volunteers who took part in this study. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.