Conditions: Hyperalgesia
Keywords: opioid induced hyperalgesia
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 22
Healthy volunteers: yes

Brief summary:
The purpose of this study was to follow a person's response to experimental pain after multiple consecutive exposures to alfentanil or diphenhydramine to see if the person can tolerate the pain more, less, or the same at the end of the study.

Detailed description:
This project investigates the phenomenon of opioid-induced hyperalgesia (OIH). Opioid analgesics, in addition to their therapeutic anti-nociceptive effects, under some conditions produce pro-nociceptive effects. This phenomenon of pain or pain sensitivity being increased by prior opioid administration is called opioid-induced hyperalgesia. It is thought to be relevant both to pain management complications and to complications of opioid dependence and its treatment. This study investigated the time-course of opioid-induced hyperalgesia development in healthy normal volunteers (N=12 completers), using a series of acute alfentanil administrations (15 mg/kg mg intramuscular (IM) per day) spaced at 3-4 day intervals, with testing for pain tolerance using the cold pressor test (CPT), and mechanical quantitative sensory testing (MQST) each administered repeatedly over time within each testing day. The goal was to determine the time course of OIH development following acute opioid administration, and to assess whether this changes over repeated acute opioid administrations.

Arms:
arm 1: Subjects received a series of acute alfentanil administrations each session (15 mcg/kg IM per session), with sessions spaced at 3-4 day intervals. arm 2: Subjects received a series of acute diphenhydramine administrations each session (25 mg IM per session), with sessions spaced at 3-4 day intervals.

Interventions: intervention 1: Alfentanil intervention 2: Diphenhydramine
Intervention descriptions: intervention 1: 15 mcg/kg IM intervention 2: 25 mg IM

Protocol document: