Commercial drug preparations may contain impurities from the manufacturing process. These impurities can give unexpected results in drug tests for opiates.
Example of a process impurity: a commercial preparation of hydromorphone may contain low levels of hydromorphone and/or oxycodone.
Typical clinical situation:
(1) A patient is receiving an opioid analgesic at a high dose and/or continuously for a long period of time.
(2) A urine drug test for opiates identifies an opiate other than the one prescribed.
(3) The physician suspects that the patient may be abusing an opiate or that someone (patient or caregiver) is diverting the patient's medication.
If an unexpected opiate is found by a urine drug test, then it is important to determine what process impurities are present in the product and then to decide if the impurities could explain the findings.
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