Combined Medication for Improved Analgesia in Superficial Pain

Potential for Improved Analgesia From Combined Medication for Superficial Pain

This research study is being done to assess if a combination of medications can enhance the relief of superficial pain (pain at the surface of the skin, such as sunburn pain). The investigators also want to find out if certain genes may be linked to individual differences in experienced efficacy of pain killers. The combination of medications under investigation is diclofenac and atropine. Diclofenac has been approved by the U.S. Food and Drug Administration (FDA) to treat pain. Atropine has been approved by the FDA to treat certain types of poisoning, heartbeat problems, and other diseases but atropine is not approved to treat pain. However, atropine has been used for many years in different European countries to treat painful conditions such as stomach cramps.This research study will compare diclofenac and atropine to placebo.

Inclusion Criteria:

• Male and female healthy volunteers.
• 18-40 years of age.
• Ability to read and understand English; English can be a second language provided that the participant feels that he/she understand all the questions used in the assessment measures.

Exclusion Criteria:

• Chronic pain condition or chronic or current treatment with any pain medication.
• Presence of any illness or medication use that is judged to interfere with the trial. For example: psychiatric disorder, medication that can influence cognition or emotional processing, i.e. sleep medication, antidepressants, anti-convulsants or opioids.
• Unwillingness to receive brief pain stimulation administered by a heat probe on the hand.
• Allergy or contra-indication to receiving nonsteroidal anti-inflammatory medication and atropine (Treatment with antidepressants, neuroleptics, antihistaminic, levodopa, anti-acids. Pregnancy, breast-feeding, myasthenia gravis, pyloric stenosis, gastro-esophageal reflux, gastric ulcer, constipation, prostatic enlargement, glaucoma, cardio-pulmonary condition -including tachycardia, arrhythmia, arteriosclerosis-, hyperthyroidism, high blood pressure, genetic disease, kidney failure)