Abstract
Caffeine is a component of popular beverages such as coffee and tea, as well as medicines for the common cold. We attempted to develop a method of simultaneous LC-MS/MS measurement of the concentrations of caffeine, ibuprofen, ethenzamide, and loxoprofen in blood. The mass-to-charge ratios of the precursor and product ions of caffeine were 195.1 and 138.1 m/z, respectively. The recovery of caffeine by column extraction using cartridges (HLB, SAX and OPT) was more than 90%, with the highest recovery obtained using the HLB cartridge. The limit of detection using the HLB cartridge was 0.01 μg/mL. Caffeine was eluted at 1.1 min when the ibuprofen method was applied, and theophylline interference was not detected in the caffeine SIM. We applied this measurement method to a pharmacokinetic study of caffeine in blood after oral intake of canned coffee. The peak caffeine concentration was 5.65 μg/mL at 60 min, and it decreased with a half-life of 360 min. This rapid and simultaneous measurement of the concentrations of caffeine and anti-inflammatory agents such as ibuprofen and others in blood would be useful in the critical care of patients intoxicated with these drugs.
