Presented at the 2012 AAPM Annual Meeting « Back

Tricyclic Antidepressants in the Treatment of Neuropathic Pain: Is Your Patient Taking Them?

Sophie J. Bordson, BS, sbordson@ucsd.ed^u1, Rabia S. Atayee, PharmD BCPS², Joseph D. Ma, PharmD³, Brookie M. Best, PharmD MAS⁴, Amadeo J. Pesce, PhD DABCC⁵, (1) University of California–San Diego Skaggs School of Pharmacy and Pharmaceutical Sciences, San Diego, California, (2) UCSD Skaggs School of Pharmacy, La Jolla, California, (3) Pharmacy, La Jolla, California, (4) UC San Diego, La Jolla, California, (5) Millennium Research Institute, San Diego, California

Introduction: Tricyclic antidepressants (TCAs) are first-line treatment for neuropathic pain, but medication adherence has not been assessed for this indication. Since they are also prescribed for sleep disorders and depression, pain specialists may not always be informed of patient TCA use. Methods: This was a retrospective analysis of urinary excretion data and physician-reported medication lists obtained from routine monitoring of patients with pain between September 2010 and May 2011. All data were de-identified and the UCSD IRB granted IRB-exempt status. Urine specimens were analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) at Millennium Laboratories for the presence of amitriptyline, nortriptyline, and imipramine. Subjects were considered adherent if the TCA was present in their urine and medication list; the monitoring physician was considered uninformed if the TCA was present in the urine but not the medication list. Drug interactions were defined using the medication database Clinical Pharmacology. Results: Of 55,296 eligible subjects, 2,141 reported TCA use and an additional 1,548 had TCA detected in their urine. The adherence rate was 66% (1410/2141). Physicians were uninformed for 3% (1548/55,296) of subjects and 52% (1548/2958) of TCA users. Of those with uninformed physicians, 20% had potentially serious drug interactions. Conclusions: Adherence rates for TCAs in pain patients were low, and more than half of TCA users did not inform their physician. Proactively discussing patient medications and updating medication lists may help improve medication adherence and prevent drug interactions.

Funding: An unrestricted grant was given to the UCSD Skaggs School of Pharmacy and Pharmaceutical Sciences to fund the summer internships by Millennium Laboratories, Inc.