A Phase 2 Clinical Trial Examining the Effects on Osteoarthritic Knee Pain of CGS-200-1, CGS-200-5 and Vehicle Control

This is a multi-center, randomized, double-blind clinical trial to examine the comparative effects on OAKP of CGS-200-1 (1% Capsaicin content) (N=40), CGS-200-5 (5% Capsaicin content) (N=40), and CGS-200 Vehicle (no Capsaicin) (N=40) in subjects with OA of the knees according to the 1986 American College of Rheumatology (ACR) criteria. Assigned doses will be applied at the clinic for 60 minutes on each of four consecutive days.

Subjects will be randomized to one of the three Arms in this study: CGS-200-1 or CGS-200-5 or CGS-200 Vehicle (CGS-200-0). All subjects will receive 4 consecutive days of treatment and will then be followed up until the Day 94 visit.

Even though both knee(s) will receive application of study test materials, with regard to reduction in WOMAC pain and VAS pain score associated with study treatments, only one knee will be indicated as the "Study Knee". This will be the knee with the highest WOMAC pain score at screening. If both knees have equal WOMAC pain scores at baseline, then the right knee will be considered the "Study Knee" with regard to WOMAC pain and VAS pain score reduction.

Data will be collected from Day 1 through Day 5 and then again on Days 19, 35, 64 and 94 for efficacy, tolerability, and safety measures. The Investigators, all site staff and Clinical Research Organization (CRO) personnel (except the Medical Monitor providing safety oversight) directly involved in the study will remain blinded to the treatment assignment throughout the trial.

Eligibility Criteria:
Inclusion Criteria:

* Osteoarthritis (OA) of both knees;
* OA of both knees must be confirmed by tibiofemoral joint radiographs obtained within the past 6 months;
* Rheumatoid factor (RF) negative and Erythrocyte sedimentation rate (ESR) \<40 mm/hr;
* Chronic knee pain in at least 1 knee for \> 3 months;
* WOMAC pain score of \> 250 (using VAS WOMAC format) at screening, and at baseline, in at least one knee;
* Knee pain score of \> 5 on the NRS pain scale at screening, and at baseline, in at least one knee;
* Knee pain is not potentially due to acute trauma unrelated to OA (no acute traumatic knee injury in medical history);
* No burning-stinging pain, unrelated to subject's knee pain, at intended site of application;
* Knee pain must be greater than pain in any other part of subject's body;
* American College of Rheumatology (ACR) global functional status I, II, or III (excluding IV).

Exclusion Criteria:

* Spontaneously improving or rapidly deteriorating OA of the knee;
* Rheumatoid or psoriatic arthritis, or a form of arthritis (e.g. gout, pseudogout), Paget's disease of bone, or any other disease affecting the joints that are inconsistent with a diagnosis of idiopathic OA;
* Labile or poorly controlled hypertension;
* Use of steroids for 1 month prior to screening, or intraarticular-visco-supplementation within 3 months prior to screening;
* Used any capsaicin-containing product on or in the vicinity of the knee within 4 weeks prior to screening;
* Used topically applied products (including emollients or moisturizers) on or in the vicinity of the knees or shaved the knees within 2 days prior to the first application of study drug; or an open wound near the knee; cutaneous erythema or edema; any inflammatory skin lesions such as eczema or psoriasis; cutaneous infections; or any other compromise of the skin;
* Requires or anticipates any surgical procedure within 3 months prior to screening, has had surgery on the affected joint within 6 months prior to screening, has a prosthesis in either knee, or would require surgery while participating in the trial.