A double-blinded randomized clinical trial: Topical Sahasthara extract versus diclofenac for treating primary knee osteoarthritis using microemulsions as a topical delivery system.

BACKGROUND AND AIM: Sahasthara (SHT), a traditional Thai herbal remedy used for anti-inflammatory and musculoskeletal disorders, lacks clinical evaluation as a topical formulation employing microemulsion (ME) technology. This study aimed to assess the efficacy and safety of a Sahasthara microemulsion (SHT-ME) compared with a diclofenac microemulsion (DF-ME) in patients with primary knee osteoarthritis (OA).

EXPERIMENTAL PROCEDURE: Eighty-four patients aged 40-70 years were randomized to receive either 1% SHT-ME or 2% DF-ME, applied three times daily for 28 days. Efficacy was evaluated using the pain visual analogue scale (VAS), 100-m walking time, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, and global assessments. Safety assessments included physical examinations, laboratory tests, and adverse-event monitoring.

RESULTS

Both formulations significantly reduced VAS pain scores, improved walking time, and decreased WOMAC scores at days 14 and 28 compared with baseline (P < 0.05). No significant efficacy differences were observed between groups (P > 0.05). Liver and renal function, blood pressure, and biochemical parameters remained within normal ranges, and no severe or skin-related adverse events occurred in either group.

CONCLUSION

SHT-ME provided efficacy comparable to DF-ME in relieving pain and improving mobility in knee OA. Both treatments were well tolerated and safe. These findings suggest that SHT-ME, a natural herbal alternative, and DF-ME, a synthetic drug formulation, are equally effective topical microemulsions for knee osteoarthritis management.