Detection and quantification of prostaglandin E₂ in saliva by liquid chromatography-tandem mass spectrometry using...

The detection of eicosanoids in saliva samples can assist pharmacokinetic/pharmacodynamic studies due to the facility of obtaining samples, minimal discomfort and high adherence of volunteers to the study. The present study enabled determine prostaglandin E₂ concentrations in saliva samples, using a microextraction by packed sorbent methodology and subsequent detection in liquid chromatography-tandem mass spectrometry. Twelve volunteers underwent scaling and coronary-radicular polishing of the upper molars and sequential saliva collections: 0.25-96 h after ingestion of a 600 mg ibuprofen tablet, to quantify prostaglandin E₂ concentrations. There was an increase in the level of prostaglandin E₂ with a significant difference after the dental procedure (0.25 h) compared to 11, 24, 48 and 72 h (*p < 0.05). After taking the drug, these levels begin to decrease up to 5 h, returning to normal in the subsequent hours. The method was developed and validated with linearity between 2.4 and 1250 ng/mL and r2 above 0.9932. The limit of quantitation was about 2.4 ng/mL. The coefficients of variation and the relative standard errors of the accuracy and precision analyzes were < 15%. The proposed extraction and analysis methodology proved to be efficient, fast and promising for pharmacokinetic/pharmacodynamic assays after using anti-inflammatory drugs.