Oral Fluid (Saliva) Analysis for Drugs of Abuse (part 2)

Dr. Joseph E. Graas, Scientific Director
Dr. Edward Moore, Medical Director

Part 1 of this article appeared in the April issue of Toxicology Times

Because the oral fluid sample collection process is usually under direct observation, the chance that the donor can adulterate the specimen is all but eliminated.  Often times the urine collection process is not observed and takes place behind closed doors, providing an opportunity for the urine sample to be diluted, spiked or substituted.  This is not a concern with observed oral fluid collections.  And unlike a urine sample, the integrity of a saliva sample is not affected by patient over-hydration.  Further, collecting a saliva sample can take place virtually anywhere, observed by any staff member and a bathroom is not required.

Despite the unlikelihood that a saliva sample would be adulterated, there are suggested procedures a program should follow to ensure the best possible sample is collected.  The patient should not consume any food or liquids five minutes prior to collection.  If there is any doubt that there might be a foreign substance in the patient’s mouth (for example, mouthwash), the patient should (under observation) rinse their mouth with water and wait 5-10 minutes before the collection process begins.  Within this time the body resumes regular saliva production and the saliva returns to the concentration of drugs that are currently in the body.

While Methadone is tested for in saliva, Methadone Metabolite is not typically found in an oral fluid sample.  The presence of Methadone in saliva may only be detected due to very recent consumption or its presence in the patient’s mouth.  But it is entirely possible the patient skipped a Methadone dose within the previous 24-hours, which would be verified by a negative Methadone Metabolite result. Testing for both Methadone and Methadone Metabolite – which can be done in urine – is the best way to fully monitor a patient and ensure that a dose has not been skipped.  For further explanation on the relationship between Methadone and Methadone Metabolite testing in urine and oral fluid samples, refer to the October and November 2011 issues of Toxicology Times.

Some patients may have a difficult time producing enough saliva (or any at all) for testing.  Generally speaking, patients in treatment programs are not well-hydrated.  Some get dry mouth syndrome which can in part be caused by the anxiety of the collection process.  In these instances, certain trigger words (pickles, sour candy, etc.) can be used to encourage saliva production.  SDRL requires a minimum of 1.5 mL of saliva per sample so that enough of the specimen exists in the event that additional testing is required.

Cost is a major factor for some programs when considering whether to institute oral fluid or urine drug testing.  While there are advantages to oral fluid testing – collection convenience, real time values and elimination of adulteration – it is generally a much more expensive test.  Beyond the laboratory testing, there is also usually an additional charge for the saliva collection device.  Furthermore, testing results from saliva screens must be confirmed by either the GC/MS or LC/MS methodologies which are typically more expensive.  Unlike for certain drugs in urine samples, the TLC confirmation methodology (typically less expensive than GC/MS or LC/MS) cannot be used on saliva samples.