Trial to See if Topical Pennsaid for Knee Pain Affects Coagulation Values in Patients Who Are Also Taking Anticoagulants

The purpose of this study is to see if using a topical nonsteroidal antiinflammatory drug (Pennsaid) to treat osteoarthritis knee pain will affect coagulation values in patients who are also taking anticoagulant or antithrombotic medications.

Open-label active treatment Phase III study of Pennsaid (diclofenac sodium 1.5% topical solution) to determine the effects on coagulation parameters in patients who are equal to or greater than 55 years of age with moderate to severe osteoarthritis knee pain and who are also taking warfarin, dabigatran, or aspirin and/or clopidogrel.

Eligibility Criteria:
Inclusion Criteria:

* Male or female adults \> than or equal to 55
* Ambulatory subjects with moderate to severe osteoarthritis (OA) of the knee with symptoms and knee pain for at least 3 months and pain on the majority of days in the last 30 days.
* Subjects with bilateral knee OA, the more symptomatic knee is the index knee and PENNSAID can be applied on both knees if both are affected.
* Radiographic evidence of Kellgren-Lawrence Grade 2-4 within the past 2 years.
* Currently on a stable dose of anticoagulant therapy (warfarin, dabigatran, aspirin or clopidogrel) for the past 2 months and expected to remain on current dose for the six week duration of the study.
* If currently taking oral nonsteroidal antiinflammatory drug (NSAID) and/or acetaminophen for OA knee pain, must be taking it for at least an average of 25 days per month.
* Those currently taking oral NSAID must be willing to perform a 7 day washout to be eligible to be enrolled into the study.
* A pain score of \> than 40mm on the Patient Pain Visual Analog Scale (VAS) (100 mm scale) at screening and baseline visit.
* Able to comply with the study and give informed consent prior to performance of any study procedures.
* Able to read, write and understand English.

Exclusion Criteria:

* Unwilling to abstain from oral NSAIDs and/or other analgesic medication except for acetaminophen as rescue medication. Subjects taking low dose aspirin for cardiovascular health may remain on their stable dose throughout the study.
* Unwilling to abstain from taking \< than or equal to 1500mg of acetaminophen a day for rescue medication purposes during the 6 week course of the trial.
* Using a handicap assistance device i.e. cane, walker \> than or equal to 50% of the time.
* Undergoing new physical therapy or participating in a weight loss or exercise program that has not been stable for at least 3 months prior to screening and won't remain stable during participation in study.
* History or diagnosis of an inflammatory arthritis i.e. rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, arthritis associated with inflammatory bowel disease, sarcoidosis, or amyloidosis.
* Known or clinically suspected infection and human immunodeficiency virus (HIV), or hepatitis C or B viruses.
* History of abnormal laboratory results \> that or equal to 2.5 x upper limit of normal (ULN) indicative of any significant medical disease which in the opinion of the investigator, would preclude the subjects participation in the study.
* Any of the following abnormal laboratory results during screening:
* Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) \> than or equal to 2.5 x ULN
* Hemoglobin \< than 11.5 g/dL (female) or \< 13.2 g/dL (male)
* White blood cell count (WBC) \< than 3500 cells/mm3
* Lymphocyte count \< than or equal to 1000 cels/mm3
* Serum creatinine \> than or equal 1.5 x ULN
* Platelet count below the central laboratory lower limit of normal (LLN)
* Coagulation tests (Prothrombin Time (PT), Partial Thromboplastin Time (PTT), International Normalized Ratio (INR), Platelet Aggregation) requiring an alteration in anticoagulant dosage.
* Skin breakdown or rash at knee where topical PENNSAID is to be applied.
* Other serious uncontrolled non-malignant, significant, acute or chronic medical or psychiatric illness that, in judgment of investigator, could compromise subject safety, limit subject's ability to complete study and/or compromise the objectives of study.
* History of malignancy in the past 5 years with exception of resected basal cell carcinoma, squamous cell carcinoma of the skin, or resected cervical atypia or carcinoma in situ.
* History of drug or alcohol dependence or abuse in the past 3 years.