Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

OXYCS
83654
P50
9110
Test Performed By: Medtox Laboratories
402 W. County Road D
St. Paul, MN 55112
Oxycodone, Serum
Clinical Information: Oxycodone hydrochloride is an opioid analgesic with several actions
qualitatively similar to those of morphine. The clearance half-life of oxycodone is approximately 3 to 6
hours.(1) Although its own strong analgesic activity precludes oxycodone from being considered a
prodrug, it is also converted to a highly active metabolite, oxymorphone, through the activity of the
cytochrome P450 enzyme CYP2D6.(2) This conversion appears to be less of a concern for CYP2D6
poor metabolizers, since oxycodone itself still provides analgesia, than for ultra-rapid metabolizers who
could be at increased risk for adverse effects.(3)
Useful For: Monitoring oxycodone therapy Assessing toxicity Routine drug monitoring is not
indicated in all patients. Because drug diversion (use of prescription drugs for recreational purposes) is a
possibility, compliance monitoring is indicated in patients being treated for chronic pain requiring high
doses (>40 mg twice a day)
Interpretation: The minimal effective peak serum concentration of oxycodone for analgesia is 10
ng/mL from a dose of 5 to 10 mg of regular release oxycodone (Percodan).(1,4) Patients develop
tolerance to oxycodone and may require larger doses for effective management of chronic pain.
Reference Values:
10-120 ng/mL
Clinical References: 1. Baselt RC: Oxycodone. In Dispositition of Toxic Drugs and Chemical in
Man. Eighth edition. Edited by RC Baselt. Foster City, CA, Biomedical Publications, 2008,
pp1166-1168 2. Riley J, Eisenberg E, Muller-Schwefe G, et al: Oxycodone: a review of its use in the
management of pain. Curr Med Res Opin 2008;24:175-192 3. de Leon J, Dinsmore L, Wedlund P:
Adverse drug reactions to oxycodone and hydrocodone in CYP2D6 ultrarapid metabolizers. J Clin
Psychopharmacol 2003;23:420-421 4. Gutstein HB, Akil H: Chapter 21: Opioid analgesics. In
Goodman and Gilman's The Pharmacological Basis of Therapeutics. Eleventh edition. Edited by LL
Brunton, JS Lazo, KL Parker. New York, McGraw-Hill Inc, 2006. Available at
http://www.accessmedicine.com/content.aspx?aID=940653
Oxygen Dissociation, P50, Erythrocytes
Clinical Information: Abnormal oxygen-affinity is demonstrated in the presence of some
hemoglobin variants: -High oxygen-affinity causes erythrocytosis -Low oxygen-affinity causes cyanosis
Increased oxygen-affinity of hemoglobin, reflected in a low p50, left-shifted oxygen dissociation curve,
and loss of normal sigmoidal configuration, is characteristic of many hemoglobin variants that are
responsible for polycythemia. Measurement of oxygen-affinity is the most important method for
diagnosis of these disorders.
Useful For: Identifying hemoglobin variants associated with polycythemias
Interpretation: Normal: p50=24mm Hg to 30 mm Hg (with sigmoidal O2 dissociation curve)
Reference Values:
24-30 mm Hg
Clinical References: Beutler E: Polycythemia. In Williams Hematology. Sixth edition. Edited by
E Beutler, MA Lichtman, BS Coller, TJ Kipps. New York, McGraw-Hill Book Company, 2001, p 689
Current as of January 3, 2013 2:22 pm CST 800-533-1710 or 507-266-5700 or MayoMedicalLaboratories.com Page 1359