Conditions: Hyperalgesia
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 10
Healthy volunteers: yes

Brief summary:
This research study explores whether a beta-blocker (propranolol) can prevent a person from becoming more sensitive to pain after administration of an opioid (remifentanil). Beta blockers inhibit the sympathetic (fight or flight) response and are often used to treat angina and high blood pressure. In a previous study in human volunteers, the investigators demonstrated an increased sensitivity to pain after a 60-minute infusion of the opioid remifentanil. The goal of this study is to identify a possible inhibitor of this phenomenon.

Detailed description:
Recent evidence suggests that opioid therapy may cause a biphasic response, i.e. initial pain relief followed paradoxically by a longer lasting hypersensitivity to pain. Recent genetic analysis in mice suggests that beta adrenergic receptor antagonists reduce opiate-induced hyperalgesia (OIH). The purpose of this study is to determine the analgesic and antihyperalgesic properties of the beta-blocker propranolol on remifentanil-induced hypersensitivity in humans.

The investigators want to determine the analgesic and antihyperalgesic properties of the beta-blocker propranolol on remifentanil-induced hypersensitivity in humans. The investigators hope to learn whether the administration of beta-blocker propranolol will significantly diminish the hyperalgesic response after administration of an opioid.

The primary outcome measure for this study is change in size (area) of secondary hyperalgesia after cessation of remifentanil infusion, a measure of OIH.

Arms:
arm 1: Propranolol, a beta blocker, or placebo to match, will be given to test whether or not it could modulate the expression of remifentanil-induced postinfusion hyperalgesia (RPH) during two pain test including: mechanically evoked pain to map the size of the hyperalgesic skin region caused by electrical stimulation and heat pain. arm 2: Propranolol, a beta blocker, or placebo to match, will be given to test whether or not it could modulate the expression of remifentanil-induced postinfusion hyperalgesia (RPH) during two pain test including: mechanically evoked pain to map the size of the hyperalgesic skin region caused by electrical stimulation and heat pain.

Interventions: intervention 1: Propranolol intervention 2: Placebo to Match Propranolol intervention 3: Remifentanil
Intervention descriptions: intervention 1: Propranolol administered intravenously, initially set to target plasma concentration of 5 ng/mL, titrated upward in 5 ng/mL intervals until a final concentration of 15 ng/mL is achieved. intervention 2: None intervention 3: Remifentanil administered intravenously at a plasma concentration of 3 ng/mL.

Protocol document: