Combined Medication for Improved Analgesia in Superficial Pain

Study Overview
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Brief Summary
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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.

Official Title
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Potential for Improved Analgesia From Combined Medication for Superficial Pain

Conditions
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Pain

Intervention / Treatment
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* Drug: Diclofenac and Atropine combination drug
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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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)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Pain medication: diclofenac and atropine<br>Diclofenac and Atropine combination drug Provided PO. This is a novel combination. Diclofenac 100mg + Atropine 1.2 mg in one single dose | Drug: Diclofenac and Atropine combination drug<br>* Diclofenac will be associated with a small dose of atropine 1.2mg<br>* Other names: Atropine and diclofenac;|
| Placebo Comparator: placebo<br>Placebo capsules will be delivered in same number as the medication | Drug: Placebo<br>* For each capsule of active medication, a capsule of placebo will be provided, identical looking.<br>* Other names: Placebo control for the active medication;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pain Scores on Standardized Experimental Pain Testing | Pain scores on standardized experimental pain testing, with collection of Visual analog scales (VAS) on a 0-100 scale 0 (no pain)- 100 (worst pain imaginable) Higher values represent a worse outcome (more pain) | baseline and 1 hour pain measurement | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Catechol-O-methyltransferase (COMT) Polymorphism Correlation With Pain Relief | Difference in the baseline pain measurements compared to the 1-hour outcome measure will be correlated with Catechol-O-methyltransferase polymorphism | baseline and 1 hour pain measurement | 
| Side Effects | The investigators aimed assess if these would be a reason for discontinuation of treatment in a population with mild to moderate pain.Side effects will be assessed with a dichotomous measurement (yes/no) | baseline and 1 hour pain measurement |