As discussed earlier, adulterants are chemicals that can be added to a urine sample to obscure or confound drug screens. Since most urine collections in the pain management setting are self-collected and unsupervised, it is easy for a person to adulterate his/her specimen if the person wishes to deceive the clinician. Adulteration of a urine sample for drugs-of-abuse screening is usually done in an attempt to produce a false-negative result. However, adulteration of the urine sample in the pain management setting can be done to produce a false-positive result. That is, a patient may adulterate the urine sample by adding the drug that should be there when in fact, the patient did not ingest the drug. The most common example of this is a patient who is being given methadone to treat heroin addiction. These patients may add methadone pill dust into their urine sample to trick the clinician into thinking he/she is compliant with taking the medication. In reality, the patient skipped the methadone dose in order to get a greater "high" when using heroin or other opiates. For this reason, toxicology laboratories should only report methadone as positive when they detect the parent and the metabolite. This is because the metabolite for methadone (2-ethylidene-1,5-dimethyl 1-3,3-diphenylpyrrolidine, also known as EDDP,) will only be present if the drug was injected and will not be present if pill dust is added.
