Effects of Pennsaid on Clinical Neuropathic Pain

The research study will compare Pennsaid to placebo. The placebo looks like Pennsaid, but it
doesn't contain any Pennsaid. The investigators use placebos in research to see if the
results are due to the study drug or to other reasons. At some time during the study the
investigators will give the patient Pennsaid. At another time, the investigators will give
the patient placebo. The investigators are using Quantitative Sensory Testing (QST), which
is temperature testing before and after using the study drug to see if Pennsaid is helpful
in reducing people's nerve pain.

In this test, a small metal plate, about the size of a matchbox, is put on the area where
the patient has pain. The plate is connected to a computer that can warm or cool the plate.
The patient will use a computer mouse button to tell us when the plate feels warm. The QST
machine is approved by the Food and Drug Administration (FDA). It is often used by nerve
doctors to see if a person has neuropathy (pain caused by damage to a nerve).

Inclusion Criteria:

1. Subject will be between 18 and 80 years of age.

2. Subject has not been on Pennsaid or other topical non-steroid anti-inflammatory drugs
for at least one month.

3. Subject agrees to make no change in his/her current pain medications during the
entire study period. This requirement will ensure that valid comparisons of primary
and secondary measures can be made before and after the study.

4. Subject has a VAS pain score of 4 or above at the beginning of the study.

5. Subject has had a neuropathic pain condition such as those listed above for at least
three months. This requirement is to avoid clinical uncertainty from an unstable
pain condition and to minimize the study variation.

6. Female subjects of childbearing age must have a negative urine pregnancy test at the
initial visit.

Exclusion Criteria:

1. Subject has documented severe liver or renal disease that will affect the elimination
of Pennsaid or is subject to the adverse effect of Pennsaid on these organs. (Renal
dysfunction is defined as eGFR < 60. Hepatic dysfunction is defined as LFTs ≥ 3X
ULN.)

2. Subject has pending litigation related to the neuropathic pain condition.

3. Subject has active skin lesion or open wound at the site of Pennsaid application
(e.g., active shingles with skin lesions).

4. Subject is pregnant or lactating.

5. Subject has scar tissue or sensory deficit at the site of QST.

6. Subject is allergic to diclofenac or has cross-sensitivity to other non-steroid
anti-inflammatory drugs.

7. Subject has a positive urine (illicit) drug test.

8. Subjects who experience asthma, urticaria or an allergic type reaction when taking
aspirin or NSAIDs.

9. Subjects undergoing coronary artery bypass surgery.

10. Subject with a known history of cardiovascular disease, ulcer, gastrointestinal bleed
or impaired renal function.

11. Subjects currently using NSAIDS.