Treatment of chronic pain is a major clinical challenge since chronic pain is frequent and leads to deterioration of quality of life. An injury or wound can lead to long term changes in the nervous system that make the skin more sensitive at and near the injury; this is termed hyperalgesia and occurs through long term depotentiation (LTP), i.e., a change in the synaptic interaction between neurons. Opioids are the gold standard for the symptomatic therapy of moderate to severe pain. Now, in animal studies the investigators have discovered previously unrecognized effects of opioids. Intradermal injection of capsaicin (injection of pepper extract into the skin) is an established pain model in humans. The investigators want to test the influence of remifentanil, an ultra-short acting opioid, on hyperalgesia observed after intradermal capsaicin in human volunteers in a double blind cross-over prospective active placebo controlled clinical trial.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
QUADRUPLE
Enrollment
24
Remifentanil (Ultiva ®; Glaxo-Smith-Kline; Vienna, Austria) at an initial dose of 0.24 µg kg-1 min-1 will be applied iv during 60 minutes.
Midazolam (Dormicum®; Roche; Vienna, Austria) will be applied iv as active placebo at a dose of 7.5 µg.kg-1.min-1 over 10 minutes to mimic typical central nervous side effects of remifentanil.
Department of Anaesthesia, Medical University of Vienna
Vienna, Austria
RECRUITINGArea of pin prick hyperalgesia
Time frame: 0-6 hours
Stimulus-response (SR)function to a set of modified rigid von Frey filaments (8-512 mN)
Time frame: 0-6 hours
Pain immediately after injection
Time frame: 0-15 minutes
Heat pain threshold within the area of mechanical hyperalgesia
Time frame: 0-6 hours
Mechanical pain threshold within the area of pin prick hyperalgesia, area of dynamic allodynia to brush
Time frame: 0-6 hours
Adverse effects
Time frame: 10 and 30 min after infusion of study medication
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