Conditions: Osteoarthritis, Knee
Keywords: knee pain, capsaicin, topical, osteoarthritis
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 120
Healthy volunteers: no

Brief summary:
This is a study of an over-the-counter, capsaicin-based (0.25%) topical analgesic for management of osteoarthritis knee pain meeting the US Food and Drug Administration's (FDAs) Tentative Final Monograph (TFM) guidance for "External Analgesic Drug Products For Over-the-Counter Human Use," published in the Federal Register on February 8, 1983 (final proposed 21 CFR 348). Subjects meeting the inclusion criteria and not meeting the exclusion criteria were randomized into one of four groups: once daily treatment with active product, once daily treatment with product vehicle (no capsaicin), twice daily treatment with active product, and twice daily treatment with product vehicle (no capsaicin), all for 7 consecutive days of treatment. The twice daily treatments were spaced approximately 12 hours apart. Osteoarthritis knee pain was assessed by the 100 mm visual analog scale. Osteoarthritis knee pain assessments were done each day for 28 days. Tolerability data were also collected.

Detailed description:
This is a study of a over-the-counter, capsaicin-based (0.25%) topical analgesic for management of osteoarthritis knee pain meeting the US Food and Drug Administration's (FDAs) Tentative Final Monograph (TFM) guidance for "External Analgesic Drug Products For Over-the-Counter Human Use," published in the Federal Register on February 8, 1983 (final proposed 21 CFR 348). Subjects meeting the inclusion criteria and not meeting the exclusion criteria were randomized into one of four groups: once daily treatment with active product, once daily treatment with product vehicle (no capsaicin), twice daily treatment with active product, and twice daily treatment with product vehicle (no capsaicin), all for 7 consecutive days of treatment. The twice daily treatments were spaced approximately 12 hours apart. Both knees received study drug treatment but only one knee per subject was assigned as the "study knee".

Osteoarthritis knee pain was assessed by the 100 mm visual analog scale and the response criterion was a 50% or greater reduction in osteoarthritis knee pain from baseline. Baseline was defined as the visual analog scale recorded not more than 30 minutes before the first study drug application (on Study Day 1). For subjects in the once daily (QD) groups the osteoarthritis knee pain assessments were at 12 hrs after the initial application (during Study Day 1) and 24 hours (Study Day 2) after the initial application and then once in the morning on Study Days 3 - 28. For subjects in the twice daily (BID) groups the osteoarthritis knee pain assessments were at 12 hrs after the initial application (during Study Day 1) and 24 hours(Study Day 2) after the initial application and then once in the morning and once 12 hours later on Study Days 3 - 28.

Tolerability data were also collected as reported burning-stinging pain, erythema and pruritus at the site of application.

Arms:
arm 1: 40 subjects receiving once daily application of complete drug product (contains 0.25% capsaicin) to the knee arm 2: 20 subjects receiving once daily application of drug product vehicle (i.e., with no capsaicin) to the knee arm 3: 40 subjects receiving twice daily application of complete drug product (contains 0.25% capsaicin) to the knee arm 4: 20 subjects receiving twice daily application of drug product vehicle (i.e., with no capsaicin) to the knee

Interventions: intervention 1: Capsaicin Topical Solution intervention 2: Drug product vehicle
Intervention descriptions: intervention 1: Over-the-counter Tentative Final Monograph compliant product with 0.25% capsaicin intervention 2: This is the vehicle for the active treatment drug product, but without capsaicin

Protocol document: