The naloxone eye‐drop test for opioid dependence

Abstract

AbstractThe use of topical ophthalmic naloxone to detect physiological opioid dependence was tested in two double‐blind, placebo‐controlled trials a week apart. The subject group consisted of opioid‐dependent patients on methadone maintenance treatment. The control group consisted of medical student volunteers. For trial 1, two drops of naloxone hydrochloride (1 mg/ml) were instilled in one eye of both subjects and controls, while two drops of an inert saline solution were instilled into the opposite eye. For trial 2 the procedure was repeated. However, on this occasion all controls were administered a single subcutaneous injection of morphine sulphate. Pupil diameter following administration of naloxone was measured by photographs taken at 0, 60 and 90 minutes. Complete data for both days were obtained from 15 controls and 13 subjects. A significant difference was found between mean changes in pupil/iris ratio for the control group compared with the opioid group for both trials. However, discriminant analysis revealed that the test is likely to produce significant numbers of false positive and false negative results. In addition, the test precipitated an opiate withdrawal syndrome in many subjects, and bilateral mydriasis was evident in trial 2. The naloxone eye‐drop test does not appear to be a useful tool in determining the presence of neuroadaptation to opioids.