Current Technologies and Considerations for Drug Bioanalysis in Oral Fluid

Abstract

Oral fluid analysis for drugs was first used almost 30 years ago for the purpose of therapeutic drug monitoring. Since then, oral fluid bioanalysis has become more popular, mainly in the fields of pharmacokinetics, workplace drug testing, criminal justice, driving under the influence testing programs, and therapeutic drug monitoring. In fact, oral fluid can provide a readily available and non-invasive medium, without any privacy loss by the examinee, which occurs for instance during the collection of urine samples. It is believed that drug concentrations in oral fluid may parallel those measured in blood. This feature makes oral fluid an alternative analytical specimen to blood, which assumes particular importance in roadside testing, the most published application of this sample. Great improvements in the development of accurate and reliable methods for sample collection, in situ detection devices (on-site drug detection kits), and highly sensitive and specific analytical methods for oral fluid testing of drugs have been observed in the last years. However, without mass spectrometry-based analytical methods, e.g. liquid chromatography coupled to mass spectrometry (LC/MS) or tandem mass spectrometry (LC/MS/MS), the desired sensitivity would not be met, due to the low amounts of sample usually available for analysis. This review will discuss a series of published papers on the applicability of oral fluid in the field of analytical, clinical and forensic toxicology, with special focus on its advantages and drawbacks over the normally used biological specimens and the main technological advances over the last decade, which made possible oral fluid bioanalysis for drugs.