Usefulness of saliva for measurement of 3,4-methylenedioxymethamphetamine and its metabolites: Correlation with plasma drug concentrations and effectof salivary pH

Background: Saliva is an alternative biologic matrix for drugs-of-abuse tes ting that offers the advantages of noninvasive, rapid, and easy sampling. W e studied the excretion profile of 3,4-methylenedioxymethamphetamine (MDMA) and its metabolites in both saliva and plasma, as well the effect of the d rug on salivary pH. Methods: Saliva and plasma samples were obtained from eight healthy MDMA co nsumers after ingestion of a single 100-mg dose of the drug. Concentrations of MDMA and its main metabolites, 3,4-methylenedioxyamphetamine (MDA) and 4-hydroxy-3-methoxymethamphetamine (HMMA), in saliva and plasma were measur ed by gas chromatography-mass spectrometry. Apparent pharmacokinetic parame ters for MDMA in saliva were estimated, and the saliva-to-plasma ratio at e ach time interval was calculated and correlated with salivary pH. Results: MDMA, MDA, and HMMA were detected in saliva. Salivary concentratio ns of MDMA were 1728.9-6510.6 mug/L and peaked at 1.5 h after drug intake. This was followed by a progressive decrease, with a mean concentration of 1 26.2 mug/L at 24 h. The saliva-to-plasma ratio was 32.3-1.2, with a peak of 18.1 at 1.5 h after drug administration. Salivary pH seemed to be affected by MDMA administration; pH values decreased by 0.6 units (mean pH values o f 6.9 and 6.8 at 1.5 and 4 h after drug administration vs predose pH of 7.4 ). Conclusions: Measurement of MDMA in saliva is a valuable alternative to det ermination of plasma drug concentrations in both clinical and toxicologic s tudies. On-site testing is also facilitated by noninvasive and rapid collec tion of salivary specimens. (C) 2001 American Association for Clinical Chem istry.