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Session 2: Clinical studies and clinical application of traditional & indigenous medicine

Efficacy of Capsaicin Cream Applied Once Daily to Pain in Knee

Osteoarthritis Patients

Radchada Sahaworakulsak, Natdanai Musigavong

Chaophya Abhaibhubejhr Hospital

Background and Rationale: Knee osteoarthritis (OA) was found in almost 50% of elderly
population. It causes joint pain, with physical disability and also reduces quality of life. Topical
analgesics can provide therapeutic effects on sites of inflammation. There are various topical
formulations used for the treatment of OA, such as diclofenac gel (DG) and capsaicin cream
(CC). Nevertheless common topical formulations require 3-4 times daily application which
causes inconvenience for patients. Capsaicin cream was therefore developed as a once-daily
preparation using nanotechnology to slowly release capsaicin to the affected areas. This clini-
cal trial was performed to evaluate the efficacy and safety of once-daily capsaicin cream
(ODCC).
Objective: The aim of this clinical study was to study the efficacy and safety of ODCC
for the treatment of OA. Patientsû satisfaction with the treatment was also assessed in this
trial.
Methodology: This study was a single-blinded randomized controlled trial in 90 patients
with mild to moderate knee OA. Thirty patients in each group were randomly assigned to
receive DG, CC or ODCC. Subjects in DG and CC groups applied their medication to the knee
and rubbed until dry for four times a day. For ODCC group, the ODCC was applied to the
affected knee for once daily at bedtime. Subjects were treated for a period of 4 weeks and
followed up every week. Visual analog scale (VAS) and Modified Western Ontario and McMaster
Universities Arthritis Index or WOMAC score were used as primary end point to determine
treatment efficacy and patientsû satisfaction was also assessed.
Results: Average ages in each group (DG, CC and ODCC) were 51.93±6.50, 55.21±7.15,
54.46±6.80 years old, respectively (p=0.129). Baseline of VAS and WOMAC scores in three
groups showed no difference (p=0.556). Outcome at week 0-4 in all groups showed statistically
significant reduction of VAS and WOMAC scores (p<0.001). There was no difference in VAS
and WOMAC scores between groups. Mean satisfaction scores were not different (p=0.182).
Burning sensation was found in CC and ODCC group (4.17% and 3.57%).
Conclusion: Once-daily capsaicin cream was effective in mild to moderate pain knee
OA. Comparing with other topical preparations, the efficacy of once-daily capsaicin cream in
relieving pain was not different. Most patients (75%) in ODCC group reported that they were
satisfied or very satisfied with the products. Burning sensation was reported less in ODCC
group than that in the group receiving common capsaicin cream.
Key words: Once-daily capsaicin cream, knee osteoarthritis