Pharmacokinetic analysis of platelet-activating factor in the tears of guinea pigs with allergic conjunctivitis.

Purpose: The aim of this study was to examine the levels of platelet-activating factor (PAF) and lyso-PAF in tears from experimental animals developing allergic conjunctivitis (AC). Methods: AC was induced in guinea pigs by application of ovalbumin in eye drops. Tear samples were collected from 5 actively sensitized animals and from 5 unsensitized control animals before the challenge, and 1, 2, 4, and 6 h postchallenge. C18:0-PAF, C18:0-lyso-PAF, C16:0-PAF, and C16:0-lyso-PAF levels in the tear samples were determined using liquid chromatography– tandem mass spectrometry. Results: The concentrations of C16:0-PAF, C16:0-lyso-PAF, and C18:0-lyso-PAF were measurable in both unsensitized and sensitized groups, whereas C18:0-PAF was undetectable in tear samples from either group. The levels of C16:0-PAF, C16:0-lyso-PAF, and C18:0-lyso-PAF in sensitized animals increased throughout the time course of the experiment, whereas there was no corresponding increase in the levels of these molecules in the unsensitized...