Presented at the 2012 AAPM Annual Meeting « Back

Interpretation of Oxycodone Concentrations in Oral Fluid

Christine Moore, PhD DSc, cmoore@immunalysis.com¹, Tara Kelley-Baker, PhD², John Lacey, MPA², (1) Immunalysis Corporation, Pomona, California, (2) Pacific Institute for Research and Evaluation, Calverton, Maryland

Introduction: The analysis of prescription pain medications in urine is increasing, along with the overuse and abuse of pain relievers, specifically oxycodone. Oral fluid is easier to collect than urine, is difficult to adulterate and is a reflection of free drug circulating in the body, therefore saliva drug concentrations are more closely related to blood levels than urine. The potential for establishing a therapeutic range for oxycodone in saliva was considered. Methods: Paired blood and oral fluid specimens were retrospectively studied in an attempt to establish a range for oxycodone in saliva reflective of therapeutic intake. Blood and oral fluid samples were collected simultaneously; oral fluid was collected using the Quantisal™ device. Results: The median oral fluid concentration measured was 524ng/mL; blood 53ng/mL (n = 23). The whole blood: plasma (WB: P) ratio for oxycodone is 1.3, so the median plasma concentration was 41ng/mL producing a saliva: plasma (S: P) ratio of 12. Regardless of the formulation, oxycodone plasma concentrations generally don’t exceed 100ng/mL. Based on therapeutic plasma levels, the corresponding saliva concentration range would be 120 – 1200ng/mL. The correlation between plasma and saliva concentrations was remarkably consistent (r2 = 0.84). Conclusions: A comparison of saliva to blood concentrations allowed the projection of a S:P ratio for oxycodone, and a therapeutic range in oral fluid. Oxycodone has potential for the development of tolerance in chronic users, so therapeutic ranges may be extended. However, the data provides a foundation for interpretative advances; further research for other pain medications is necessary.

Funding: The oral fluid collection device used is manufactured by Immunalysis Corporation. Some of the specimens collected were from the National Roadside Survey funded by NHTSA, NIDA, and NIAAA. The manuscript has been submitted for publication but no review or feedback has yet been received.