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Pharmacy and Medications

Prescribed oxycodone - compliance testing

05/02/2006

Question:

My doctor did an oxycodone blood test level and urine test to be sure I am taking my meds. Could you tell me what would make an oxycodone test level low

Answer:

Oxycodone is an opioid pain reliever.  Oxycodone is available in both immediate release and sustained release dosage forms. The immediate release products are often combined with acetaminophen.  Sustained release oxycodone is used to treat chronic pain.   Immediate release oxycodone is typically used to treat severe acute pain or breakthrough pain in patients also using opioid pain relievers for chronic pain.  Most patients with acute pain have a defined injury and a need for pain relief that coincides with the injury and abates as the injury heals.   Patients with chronic pain tend to need pain relief indefinitely.

In the United States oxycodone is classified as a Schedule II controlled substance.  This means it has high abuse potential.  State and federal laws aim to limit the supply of this and other potentially abused drugs.  However, demand for abuse purposes for these medicines remains quite high. It is basic economics that high demand in the face of limited supply will lead to increased prices to consumers. Abuse drugs are no different from any other commodity.  Despite the risks, a brisk black market for abuse drugs exists throughout the United States. It is a fact of life that some patients who receive prescriptions for oxycodone or other abused drugs will sell some or all of their medicine to drug abusers to supplement their income.  

Physicians must be concerned that some of their patients will attempt to divert medicines to drug abusers. Some clues pointing to possible inappropriate use or diversion include a need for pain relief beyond a normal healing time,requesting higher doses than should be needed,  and requesting a new prescription before the old prescription should have run out.  Checking for the presence of a prescribed drug in urine is one way to determine whether a patient is taking the medicine as prescribed. If the prescribed drug is not present, the assumption may be made that the patient has not been taking the medicine regularly and thus could be diverting the drug to abusers.

Testing for compliance is usually done by a urine drug screen, not by a blood test.  A specific screen for oxycodone is available and should be used for compliance testing.  With regular use of oxycodone containing pain medicines, this urine drug screen should remain positive for oxycodone for 1-2 days.  A small percentage of patients metabolize oxycodone more rapidly than normal, but this should not affect the ability of the screen to detect the drug in urine.   A more common opioid screen is based on morphine. These screens are good for detecting morphine codeine and heroin abuse, but are less likely to detect use of oxycodone and other opioids unless the levels are higher than normal. If this screen was used, oxycodone might not be detected even when a patient is using the medicine regularly.   

Ask your doctor if the lab used the oxycodone specific drug screening product.  If the lab used the screen that is more specific for morphine, it might not detect oxycodone and lead to the false impression that you were not taking the drug as prescribed.

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Response by:

Robert James Goetz, PharmD, DABAT
Assistant Professor of Pharmacy Practice
College of Medicine
University of Cincinnati