Oral fluid specimen

Initially, plasma and oral fluid specimens from patients (n = 21) on different antidepressant treatment were collected twice to assess if any of the studied analytes was likely to show a good correlation. The best results were obtained for venlafaxine (%CV for plasma/oral fluid concentrations ratio (f OF/PL) <21%). Therefore, the study was extended for this antidepressant by analysis of oral fluid and plasma specimens from five patients on venlafaxine treatment collected on four occasions. Daily doses of venlafaxine retard formulations were 75 mg for two patients, and 150 mg for the remaining participants. Collection of oral fluid (direct spitting into polypropylene tubes) and plasma (heparinized tubes) specimens was performed, when possible, before the next dose to ensure the drug was in the elimination phase. The dose and the time of collection was the same on the four different occasions for each patient. For the analysis, oral fluid and plasma specimens were centrifuged at 14 x 103 rpm, and 0.2 mL of the supernatant were extracted. In addition, correlation between the concentrations in the plasmatic free fraction and in oral fluid was also evaluated. Plasmatic proteins were eliminated by filtering 0.5 mL of plasma samples using Microcon filter devices Ultracel YM-3 (Millipore Corp., Billerica, MA, USA). 

Lew authors described antidepressant analysis in alternative specimens, such as hair or oral fluid. LC-CID-MS and MS/MS mass spectra libraries for identification of several drugs were employed by Muller et al. [32] for the detection of maprotiline, citalopram, and their desmethyl metabolites in authentic hair specimens extracted ions chromatograms were employed for subsequent antidepressant quantification. Also Klys et al. [33] applied LC-MS/MS to the analysis of blood, urine, and hair specimens in a fatal case due to clomipramine overdose in combination with alcohol. Blood clomipramine and norclomipramine concentrations explained the fatal outcome, and hair analysis confirmed that the deceased was on clomipramine treatment for, at least, 12 months prior to his death. With regard to oral fluid analysis, de Castro et al. [34] developed and validated a... 

Plasma is the main biological sample used in clinical and toxicological analysis, as concentrations found in this matrix are correlated to the pharmacological effect, as well as to the side and toxic effects. However, oral fluid has also been employed in some specific applications because of the advantages associated to this alternative specimen easy, painless, and noninvasive collection, which does not require qualified personnel, it represents the free analyte fraction, and it has a window of detection similar to that in plasma. Within the possible applications of oral fluid analysis, two are of special relevance ... 

TDM As previously stated in this chapter, TDM is recommended for TCAs and, in special situations, for the new generations of antidepressants. However, several factors can affect diffusion of the analytes from plasma to oral fluid (pH, oral contamination, collection with or without stimulation). Therefore, the correlation between antidepressant plasma and oral fluid concentrations should be studied before using this alternative specimen for TDM purposes. 

Selectivity of the method was evaluated by analysis of blank oral fluid and plasma specimens from ten healthy subjects. In addition, potential exogenous interferences were assessed by analysis of authentic plasma specimens containing other common therapeutic drugs like benzodiazepines and/or drugs of abuse. No endogenous or exogenous interferences were found in the monitored MRM channels in any of the analyzed specimens. 

Fig. 7. Excretion patterns of/l -tetrahydrocannabinol (THC) concentrations (ng/ml) in oral fluid and plasma, and urinary 1 l-nor-9-carboxy-/l -tetrahydrocannabinol (ng THCCOOH/mg creatinine) in one human subject following smoking of a single cannabis cigarette (3.55%). The ng THCCOOH/mg creatinine ratio is illustrated for all urine specimens collected through the last positive specimen. Analyses were performed by GC-MS at cutoff concentrations of 0.5 ng/ml for oral fluid and plasma and 15 ng/ml for urine. (Reproduced from the Journal of Analytic Toxicology by permission of Preston Publications, a division of Preston Industries Huestis and Cone 2004, Fig. 2 therein)...

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