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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
10
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.
Remifentanil administered intravenously at a plasma concentration of 3 ng/mL.
Stanford University School of Medicine
Stanford, California, United States
Percent Change From Baseline in Size (Area) of Secondary Hyperalgesia After Cessation of Remifentanil Infusion, a Measure of Opioid-induced Hyperalgesia (OIH).
A slightly modified version of a previously described model of secondary hyperalgesia was used. Two copper wires contained in a microdialysis catheter were inserted in parallel over a length of 5 mm into the dermis of the right volar forearm. The wires were connected to a constant current stimulator controlled by a pulse generator to deliver rectangular and monophasic pulses with a duration of 0.5 mg at 2 Hz. Over a period of 15 min, the current was increased by targeting a pain rating of 5 on an 11-point numeric rating scale (0 = no pain and 10 = maximum tolerable pain) until the hyperalgesic area surrounding the stimulation site was fully established. Once the area was established, the current was held constant. Percent change from baseline in size (area) of secondary hyperalgesia after cessation of remifentanil infusion was calculated per group.
Time frame: Baseline; 15 min post remifentanil (REM) infusion; 60 min post REM infusion
Objective Opioid Withdrawal Scale (OOWS)
OOWS: Is a 13-item instrument of documenting physically observable signs of withdrawal, which are rated as present (1) or absent (0) during the observation period. Maximum score = 13, minimum score = 0. Lower scores correspond to fewer symptoms.
Time frame: Pretreatment [90 min prior to 60-min REM infusion]; 30 min prior to 60-min REM infusion; 15 and 40 min after start of 60-min REM infusion; 5, 15, and 75 minutes after finish of 60-min REM infusion)
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.