Study on the Effect of a Beta Blocker on Increased Sensitivity to Pain in Humans Caused by Opioids

Effect of Beta Blockade on Opioid-Induced Hyperalgesia in Humans

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.

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.

Inclusion Criteria:

1. Healthy men,
2. Age between 18 and 45 years
3. Normal weight (according to the table provided by Metropolitan Life Insurance).

Exclusion Criteria:

1. Hypersensitivity to opioids or naloxone,
2. History of addictive disease,
3. Significant cardiac, respiratory, gastrointestinal, neurological, dermatological, and psychiatric diseases,
4. Concurrent medication with an analgesic drug,
5. Student and employees affiliated with our laboratory