Influence of Sampling Procedure on Codeine Concentrations in Oral Fluid

Abstract

For many drugs, there is a poor correlation between the plasma and oral fluid (OF) concentrations, due to differences in OF pH, oral contamination, stimulation of OF flow and variability of the volume of sample taken. The aim of this study was to evaluate the OF/plasma ratio and variability in drug concentration in OF sampled by two commercially available collection systems: Saliva Collection System (SCS) and Quantisal. Blood and OF samples were collected from 12 volunteers after intake of 19.5 mg codeine phosphate. Six persons were sampled by SCS first, followed by Quantisal; six other participants used Quantisal before SCS. The OF content of SCS tubes was measured spectrophotometrically. The Quantisal devices were weighed to correct for the effectively obtained OF volume. Codeine was measured by gas chromatography-mass spectrometry. The mean codeine concentration at 1 h was 29.8 ± 18.8 μg/L in plasma, 72.8 ± 63.9 μg/L in SCS OF and 85.3 ± 72.6 μg/L in Quantisal OF. The mean OF/plasma ratio was 2.30 ± 0.77 (SCS) and 2.69 ± 1.94 (Quantisal). Pearson's correlation coefficient between OF and plasma codeine concentrations was statistically significantly (P = 0.005) higher for SCS (R(2) = 0.745) than for Quantisal (R(2) = 0.403). The variability in ratios with Quantisal was markedly reduced when used after SCS. Codeine concentrations measured in OF taken with SCS correlate better with plasma concentrations than in OF obtained with Quantisal, particularly when Quantisal was used first.

Zopiclone concentrations in oral fluid and blood after, administration of therapeutic doses of zopiclone

“…The OF/plasma ratio of codeine was investigated in one study and it was found that the ratio depends on which OF collection kit is used. The correlation coefficient between OF and plasma codeine concentrations was statistically significantly (p=0.005) higher for the Saliva Collection System (R 2 =0.745) than for Quantisal (R 2 =0.403) (176). Quite constant OF/blood (serum) concentrations have been found for theophylline (177) and diazepam (178).…”

Towards adherence monitoring using breath or oral fluid as a matrix in a methadone maintenance treatment program for patients with a chronic heroin use disorder: Issues and interpretation of the results

“…When oral fluid samples are adulterated, for as by sucking on the pad or placing water in the mouth, an unexplained deviation in the oral fluid samples collected can occur. Only 3.5% of the 86 oral fluid samples were found to be outside our predefined gravimetrical analytical reference value of 0.5-1.5 grams based on results from the literature (5,13,14).…”

Proteomics of the Salivary Fluid

“…Therefore, an optimized sample collection process is needed, and a researcher must carefully and cautiously prepare the sample collection step, and the patient must be educated and trained if sample is being to be collected at home. Furthermore, steps like sample storage and transport to the laboratory must also be carefully planned and executed especially when longitudinal studies of the same patient or of the patients' groups are being performed, and especially in parts of the world where appropriate infrastructure is not always available [40][41][42][43][44][45].…”