The Efficacy of Diclofenac Gel for Breakthrough Pain and the Neuropathic Components of Pain in Knee Osteoarthritis

Phase 4

Completed

Brief Summary: The purpose of this proposed study is to conduct a trial with knee osteoarthritis (OA) patients using the diclofenac gel.

Detailed Description: The purpose of this proposed study is to conduct a trial with knee OA patients using the diclofenac gel. The effectiveness of diclofenac gel in managing breakthrough pain or the neuropathic components of pain (e.g., the burning, soft tissue joint sensitivity, or allodynic components) in knee OA is unknown. It is likely that patients will use the gel in a as needed (prn) fashion, on top of other analgesics prescribed for their pain. The neuropathic components of a generally nociceptive or inflammatory condition, such as knee OA, are underappreciated, and typically not tracked in OA analgesic studies. Yet, evidence across a variety of chronic painful conditions suggests that these components are quite disabling. The results of this study would show whether diclofenac gel as a prn medication is beneficial to patients suffering from knee OA pain.

Recruitment & Eligibility

Inclusion Criteria

Ages 20-75
Unilateral or bilateral knee osteoarthritis (OA), confirmed radiographically.
Patients taking oral non-steroidal anti-inflammatory drugs (NSAIDs) in the amount and schedule prior to the breakthrough period will be permitted.

Exclusion Criteria

Patients with clinical history of anterior cruciate ligament (ACL) involvement.
Patients on tricyclic antidepressants or anticonvulsants (neuropathic medications)
History of ulcers or gastrointestinal (GI) bleeding
Coagulation disorders
Hypersensitivity to Aspirin or NSAIDS
Congestive Heart Failure and Edema
Advanced renal disease
Aspirin triad
Pregnant women

Arm && Interventions

Group	Intervention	Description
Diclofenac gel	Diclofenac Gel	Diclofenac gel 4 grams (g) applied topically 4 times daily (QID) to the affected knee(s) for up to 4 weeks. Participants took a maximum dosage of 32 g/day.

Primary Outcome Measures

Name	Time	Method
Percent Change From Baseline in Pain Score During Week 1	Baseline and Week 1	Participants assessed their knee pain using a visual analog scale (VAS) where 0=no pain and 100=worst possible pain. Pain scores were recorded in an electronic diary prior to and 4 hours after the first daily application of diclofenac gel for breakthrough pain. The daily percent change in pain scores over the 7 days prior to Week 1 were averaged. Percent change from Baseline (average pain score 7 days prior to first treatment) was calculated as (value at baseline - value at post-baseline visit) / (value at baseline) x 100. A positive change from Baseline indicates improvement.
Percent Change From Baseline in Pain Score During Week 2	Baseline and Week 2	Participants assessed their knee pain using a visual analog scale (VAS) where 0=no pain and 100=worst possible pain. Pain scores were recorded in an electronic diary prior to and 4 hours after the first daily application of diclofenac gel for breakthrough pain. The daily percent change in pain scores over the 7 days prior to Week 2 were averaged. Percent change from baseline (average pain score 7 days prior to first treatment) was calculated as (value at baseline - value at post-baseline visit)/ (value at baseline) x 100. A positive change from baseline indicates improvement.

Secondary Outcome Measures