Effects of Lidocaine Patch on Intradermal Capsaicin Induced Pain and Hyperalgesia

University of California San Diego

Status and phase

Completed

Phase 1

Conditions

Hyperalgesia

Pain

Treatments

Drug: Lidoderm Patch

Study type

Interventional

Funder types

Other

Identifiers

NCT00373893

051252

Details and patient eligibility

About

To determine the effects of Lidocaine patch on the pain and hyperalgesia induced by intradermal capsaicin

Full description

A randomized, double-blinded, placebo controlled methodology will be conducted. At the session subjects will be exposed to placebo patch and lidocaine patch. Prior to study drug administration, a baseline neurosensory test on the volar aspect of both forearms will be performed and baseline vital signs will be measured. A placebo patch and a lidocaine patch will then be applied to the volar aspect of each forearm. The arms will be randomized to which arm receives placebo and which one receives the lidocaine patch. After four hours of application the right forearm patch will be removed the neurosensory testing will be repeated on the right forearm. After completing the testing, capsaicin (10µl, 10 mg/ml) will be injected intradermally on the volar aspect of the right forearm. Elicited and spontaneous pain scores, blood pressure, heart rate, and respiratory rate will be measured at the time of injection and every 2.5 minutes for 10 minutes. A McGill Pain Questionnaire will be administered at the time of capsaicin injection only. Ten minutes after the capsaicin injection, the hyperalgesic area will be established to von Frey hair, stroking, and heat; the flare response will be outlined; and neurosensory testing will performed halfway between the edge of this defined area and the capsaicin injection site. At the completion of the testing on the right forearm, the left forearm patch will be removed and the procedures described for the right forearm will be repeated for the left forearm.

Sex

All

Ages

18+ years old

Volunteers

Accepts Healthy Volunteers

Inclusion criteria

Age 18 and above

Exclusion criteria

Pregnancy.
Allergy to lidocaine
Current painful condition
Current use of analgesics for the treatment of pain
Lack of ability to understand the experimental protocol and to adequately communicate in English. The neurosensory testing we plan to perform requires the complete cooperation and understanding of the subject. It would be impossible to perform these studies on patients who do not adequately communicate in English.