Toxicology: Oral Fluid Drug Testing

John Wicks & Lolita Tsanaclis,
Cansford Laboratories Ltd., Cardiff, UK, Cardiff Medicentre, Cardiff, CF14 4UB, UK,
Tel: 029 2068 2931

Over the last 15 years there have been major advances in the Drug Testing and the use of alternative specimens to blood and urine for establishing exposure to drugs has become widespread.  The alternatives include hair, sweat and oral fluid.

Oral Fluid testing has been proposed as a non-invasive alternative to blood and has proven to be a viable alternative sample to urine for detecting drug use.  The technique has a similar level of accuracy in detection of drugs and is markedly easier to administer than a urine test though there are inevitable differences that need to be understood.

The detection of drugs in oral fluid is more challenging than detection in urine but advances in technology have eliminated any problems. The detection window for drugs in Saliva is shorter than for drugs in urine making it slightly sensitive as a screen for drug use.  The usual period covered by an Oral fluid test is typically 36 hours.  Urine testing covers 3 to 5 days.  Urine testing reveals what has been taken but not whether the donor is under the influence of the drug detected.

Oral fluid has the advantage over both blood and urine in that it can be obtained non-invasively in conditions where adulteration or substitution is difficult. And it is a sample of choice in ‘for cause’ investigations where it blood sampling might not be available or possible.

On site testing kits are available for oral fluid testing as they are for urine, though for maximum sensitivity laboratory analysis is preferable and is required for confirmation of the initial screen results.  There are a number of collection devices on the market.  Most of the commercially available collectors use a proprietary diluent to mix with the sample and have a pad on stick to place in the donor’s mouth that will collect about 1 millilitre of fluid.  The sample can usually be collected within one to three minutes. But it is very important to wait 10 minutes in the presence of the donor to ensure that any drinks or fluids held in the mouth have been swallowed before testing.   This time can be used to complete all paper work. Oral fluid testing can be turned around in the laboratory within 3 days of receipt of the sample.

Applications of drug testing in oral fluid include the monitoring of drug use by drug courts, workplace testing and roadside testing of possible drug-affected drivers. In the workplace, a testing protocol that focuses more on recent drug use that is most likely to affect work performance is attractive to many employers and Oral fluid testing fits that role better than urine.

In general oral fluid concentrations of drugs correlate with blood concentrations so that relating the presence and concentration of drugs in oral fluid to performance and clinical effects in the individual tested is more precise than with urine testing.

Published in Autumn 2011

Posted in Did you know?, Editorials