Introduction and review of collection techniques and applications of drug testing of oral fluid

The past several years have seen substantial developments in the use of alternative specimens for drug analysis. The use of oral fluid has been found to offer significant promise when detection of relatively recent use of drugs is sought in a relatively noninvasive manner. Although there are a number of factors that affect drug concentration in oral fluid, there appears to be a reasonable correlation between blood and oral fluid concentrations of drugs. Collection techniques can artificially affect production of oral fluid and its subsequent pH. These need to be understood, as does local absorption of drug, in situations where drug may be present in the oral cavity (eg, smoking or sublingual absorption). Nevertheless, it is essential that devices used to collect oral fluid are checked to ensure reasonable stability and recovery of absorbed drug. The most common applications include workplace testing for drugs of abuse, particularly post-incident, and roadside detection of illicit drugs. Therapeutic drug monitoring has been shown to be useful for a number of drugs that have traditionally been measured in plasma/serum.