Hydromorphone in Urine Drug Tests is an Indicator of Morphine Therapy

February 14, 2007

Lexa W. Lee

February 14, 2007 (New Orleans) — Results of a new study confirm that hydromorphone is a minor metabolite of morphine and appears on urine drug testing (UDT), suggesting it may be used to determine whether patients are compliant with therapy.

When UDT is used to monitor patient adherence to opioid therapy, it can be unclear whether specific opioid compounds are normal or abnormal metabolites, the researchers point out.

"Hydromorphone has not been thought to be a normal metabolite of morphine in urine screens. It was thought to come from other opioids," said Ajay Wasan, MD, a psychiatrist and chronic pain researcher from Brigham and Women's Hospital in Boston, Massachusetts.

This current finding "assists in determining whether a UDT result is normal or abnormal and subsequently whether a patient is compliant with opioid therapy," Dr. Wasan and colleagues conclude.

Results were reported here at the American Academy of Pain Medicine 23rd Annual Meeting.

Todd Sitzman, MD, an anesthesiologist at the Forrest General Cancer Center in Hattiesburg, MS, commented on these results for Medscape. "This study has rewritten the toxicology reference used by practicing pain physicians. Patients taking morphine should no longer be suspected of aberrant drug behavior if hydromorphone appears in their urine. Such patients are usually referred for counseling or withdrawn from morphine therapy."

Morphine Metabolite

Dr. Wasan headed a retrospective case-control study of chronic pain patients taking only morphine.

Gas chromatography-mass spectroscopy (GCMS), which is highly accurate for UDT, with a less than 0.5% false-positive rate, was used to test for the presence of specific opioid compounds in samples positive for morphine only (these patient samples were used as controls) and in samples positive for morphine as well as hydromorphone (cases). Variables in demographics and medical history were recorded, as well as any history of aberrant drug behavior. These data were then related to the presence or absence of hydromorphone in the urine.

Hydromorphone was present in 21 cases (66%) and absent in all 32 controls. None of these 53 patients had a history of aberrant drug behavior. In this study, cases positive for hydromorphone were patients taking higher daily doses of morphine (mean dosage was 151 ± 65 mg), which resulted in higher urine morphine concentrations ( P
< .05) but a consistent hydromorphone/morphine ratio of 2%. Only morphine urine concentration (not other opioids) was a significant predictor of the hydromorphone metabolite.

Hydromorphone is apparently a minor metabolite of morphine, normally appearing in the UDT of patients taking morphine, the authors conclude, and the presence of this metabolite in UDT may assist in determining whether a patient is compliant with morphine therapy.

The findings of this study should be confirmed by more research in a controlled environment, the researchers conclude. Further investigation of variables such as patient gender, dose of morphine, urine concentration of morphine, and genetic determinants of morphine metabolism is warranted.

23rd Annual Meeting of the American Academy of Pain Medicine, February 2007: Abstract 152.


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