Journal of Drug Metabolism & Toxicology
Open Access

Abstract

Sublingual Absorption of Naloxone in a Large Clinical Population

Daniel M. Strickland and Jana K. Burson

Background and Objectives: The combination of buprenorphine and naloxone (combo product) is a medication that is administered sublingually to treat opioid use disorder as part of medication assisted treatment. The naloxone component is believed to deter inappropriate use of the medication. True allergies to naloxone are infrequent, but many patients experience severe, unpleasant side effects that they associate with the combo product but not with the formulation containing buprenorphine alone (mono product). It is commonly contended that naloxone is poorly absorbed sublingually, so we sought to test the validity of that belief.
Methods: Using a sensitive LC-MS assay, we quantified the concentration of naloxone in the urine of 61 patients (Total specimens=686) prescribed the combo product. Because this study was retrospective it was neither intended nor possible to compare adverse side effects between patients prescribed mono versus combo products.
Results: We found that 92.7% of the patients prescribed the combo product had significant quantifiable concentrations of naloxone in their urine drug screens.
Conclusions and Scientific Significance: Contrary to popular belief, naloxone is absorbed sublingually. Such absorption may account for some of the unpleasant side effects experienced by patients treated with the combo products, but it was not possible to compare or quantify side effects in this retrospective study. We feel it is important that clinicians be aware of the possibility of significant sublingual absorption of naloxone when choosing therapeutic modalities for their patients.