“…A number of illicit drugs have been detected in oral fluid including cocaine, amphetamine and derivatives, opioids, phencyclidine (PCP) and cannabinoids (Clauwaert et al, 2004;Cone, 1993;Cooper et al, ;Drummer, 2005;Idowu and Caddy, 1982;Schramm et al, 1992). Controlled drug administration studies have investigated the presence and pharmacokinetic characteristics of a number of these drugs in oral fluid (Cone, 1993;Cone et al, 1997;Jenkins et al, 1995;Jufer et al, 2000;Kacinko et al, 2004;Kato et al, 1993;Kim et al, 2002;Kintz et al, 1998;Kopecky et al, 1997;Moolchan et al, 2000;Navarro et al, 2001;O'Neal et al, 1999;Schepers et al, 2003;Skopp et al, 2001;Wang et al, 1994) Furthermore, oral fluid has been successfully applied in criminal justice programs (Yacoubian et al, 2001), workplace (Cone, 2001) and roadside drug testing (DUI) (Peel et al, 1984;Samyn and van Haeren, 2000), but little is known of the usefulness of oral fluid drug monitoring in a population of substance-abuse treatment patients.…”