Aprepitant Effects on Oxycodone Response

Addressing the issue of opioid dependence and tolerance has public health implications for the treatment of opioid abuse (both heroin as well as pharmaceutical opioids) and for the treatment of pain. Recent preclinical data suggest a role for Substance P (NK-1) receptors in modulating both the acute and chronic response to opioids. The objective of this study is to determine whether pretreatment with aprepitant, a selective neurokinin-1 (NK-1) antagonist can reduce the direct response to an opioid agonist (oxycodone) on measures related to abuse liability and reinforcing effects.

Healthy adult volunteers with histories of illicit opioid use by the intranasal and oral routes will be admitted to this 6-week inpatient, crossover study. They will participate in 15 experimental test sessions, each lasting approximately 6.5 hours, during which they will receive a range of acute doses of aprepitant, including placebo, followed by challenge with oxycodone or placebo (given intranasally or orally). Multi-dimensional outcomes, including physiological (blood pressure, oxygen saturation, pupil diameter), subjective (questionnaires related to mood, abuse liability) and observer ratings will be collected repeatedly throughout each session. Data will be analyzed using parametric approaches to within-subject designs.

Within subject crossover designed that examined 15 experimental conditions within a single group of participants

Visual analog scale ratings (from 0-100) on the subject-rated measure of "How much do you like the drug?" with higher scores indicating greater abuse liability (and 100 anchored with "extremely" and zero indicating none anchored with "none at all." Data were collected across multiple time points but the peak maximum score was used for the primary outcome measure.

Respiration rate measured over 60 seconds. Data were collected across multiple time points, but the peak minimum score was used for this outcome measure.

Inclusion Criteria: Recreational user of opioids Healthy Ages 18-55 years old Able to provide informed consent Exclusion Criteria: Ongoing medical or psychiatric condition that would be contraindicated for participation Past 30 day use of and P4503A4 inhibitor

Walsh SL, Heilig M, Nuzzo PA, Henderson P, Lofwall MR. Effects of the NK1 antagonist, aprepitant, on response to oral and intranasal oxycodone in prescription opioid abusers. Addict Biol. 2013 Mar;18(2):332-43. doi: 10.1111/j.1369-1600.2011.00419.x. Epub 2012 Jan 19.