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Urine Drug Testing Case Studies 2
Edward Chen, MD

Today, pain management physicians registered with the state as a pain management clinic are required to perform urine drug screening on all patients prescribed a controlled substance.

While obtaining a sample is at times problematic, the interpretation of the testing results can at times be confusing, and the physicians response challenging.

Below are common scenarios which are open for discussion.

 

DISCUSSION:
Marijuana is the most commonly used illicit drug. A recent survey has shown 12% of 8th graders, 29% of 10th graders, 33% of 12th graders, and 46% of high school graduates have used the drug. Amongst adult illicit drug users, 77% have used marijuana.

Patients are commonly discharged from a medical practice upon detection of marijuana from a urine drug screen. Long term marijuana use can cause addiction, with withdrawal symptoms experienced upon discontinuation. In addition, the potency of marijuana has steadily increased over the last thirty years. The patient should be made aware of the detrimental effects of the drug, and referral for addiction available.

A patient is prescribed Percocet 7.5/325 TID PRN #90/month. He requests his prescriptions every thirty days. A urine drug screen and confirmatory testing shows no opiate present. You suspect diversion and the patient returns for a random pill count which is accurate. The patient states he does not take the medication daily due to work. Would you:

 

DISCUSSION:
Public sentiment is changing over the designation of marijuana as an illicit drug. Marijuana has been shown to relieve pain, control nausea, stimulate appetite, and decrease intra-ocular pressure.

However, marijuana is still considered illegal. Marijuana contains 70% more carcinogens than tobacco smoke. There is increased risk of schizophrenia, psychosis, anxiety, depression, and insomnia. Many of our pain patients have a concurrent diagnosis of psychiatric illness, for which they are being treated and prescribed medications. There is impairment of short term memory, attention, coordination, balance, and cognition. A recent survey found nearly 7% of drivers under age 35 involved in a motor vehicle accident tested positive for marijuana, and present in 18% of motor vehicle deaths. Lastly, use can cause tachycardia, bronchitis, and suppressed immune function.

The patient is a new patient with end stage renal disease on dialysis. He is anuric. He has been prescribed Methadone 10 mg QID by his referring physician who no long wants to prescribe. Would you:

 

DISCUSSION:
While symptoms of opiate withdrawal are unpleasant, they are not life threatening. Symptoms can be treated with medications such as Clonidine, Valium, and antiemetics. Alternatively, the patient can be detoxed with Subutex (buprenorphine) or at a treatment facility. Many pain clinics will not accept new patients without reviewing previous records, and patients will not be seen in consultation until several days or weeks, in which time the withdrawal symptoms will have already passed. The PCP or referring physician may decide not to accept the patient again as well, or not prescribe pain medications, or not have the knowledge to treat the withdrawal symptoms.

A random urine drug screen is positive for THC (marijuana). The confirmatory results are read as negative for THC. The cutoff level is 50. Would you:

 

DISCUSSION:
The monthly prescription amount is important in this scenario. If the patient was only prescribed thirty pills per month, it would be reasonable to have a negative test if the last dose was several days ago and the patient takes three tablets a day twice a week on bad days. However, in this case, it would be difficult to explain PRN use of ninety pills per month. Toxicology results should detect drug present for up to 2-4 days after last dosage. It is critical to examine all possible explanations for a negative test. Verify with the pharmacy that the prescriptions are regularly filled. Some patients are reluctant to tell their physician they do not want to take the medication prescribed for fear of reprisal of following their doctor’s orders. The patient takes the prescription, but simply does not fill the prescription. Another possibility is the patient is stockpiling the medication for use at another time. The patient could also be ‘binge’ using the medications on weekends or certain days.

The obvious foremost concern is this patient is diversion. While there is no fool proof method of determining diversion, useful monitoring tools are frequent random urine drug screens and mid-cycle pill counts. Genetic testing would not be useful, as there is absence of both native and metabolized drug. Serum blood testing to determine plasma level of drug would be an accurate option to confirm proper use of medication.

DISCUSSION:
Pain physicians are increasingly finding themselves in the position of consulting on new patients from physicians who no longer wish to continue prescribing controlled substances for their patients after the passage of the 2011 Florida Prescription Drug Monitoring Program. The law’s intentional restriction on ‘pill mills’, has caused an unintentional diversion of patients to legitimate pain management clinics from multiple avenues. Primary care, rheumatologists, surgeons, and others have turned away from their patients from a misinterpretation, misunderstanding, or ignorance of the statute.

Oral fluid (saliva) can be a useful test, but has limitations. Detection is primarily of parent drug, and not metabolite. Some drugs may be present in greater amounts than detected by urine drug testing due to local deposition of drug, such as marijuana, cocaine, or sublingual Suboxone. Food can stimulate the production of saliva and decrease the presence of drug. Similarly, some physiologic conditions may decrease saliva production and prevent adequate sampling.

Other options for verification and monitoring would be serum blood testing, or forensic testing of hair.