Piroxicam ultrasound combination optimal for knee osteoarthritis

By Helen Albert, Senior medwireNews Reporter

Phonophoresis of the non steroidal anti-inflammatory drug (NSAID) piroxicam with ultrasound is more effective than ultrasound alone for improving pain and other symptoms of mild-to-moderate knee osteoarthritis (OA), show study findings.

Ultrasound is widely used to alleviate pain in patients with knee OA and other similar conditions, as it allows "elevation of the pain threshold, alteration of neuromuscular activity leading to muscle relaxation, induction of tissue regeneration, and reduction of inflammation," say study authors Wanwadee Luksurapan and Jariya Boonhong from Chulalongkorn University in Bangkok, Thailand.

Recent studies have suggested that application of a topical NSAID in combination with ultrasound to improve the drugs absorption, a technique known as phonophoresis, may improve pain relief and other symptoms of OA over ultrasound alone, but results have been conflicting to date.

In this study, the researchers compared treatment with ultrasound alone plus standard gel (controls; n=23) with ultrasound plus piroxicam gel (n=23; approximately 20 mg per application) for patients with mild-to-moderate knee OA aged 59 years on average. The patients were mostly women with one man in the piroxicam and two men in the control group.

Both the treatment groups underwent five ultrasound sessions (1.0 W/cm² stroking technique, continuous mode) a week for 2 weeks.

Before and after treatment, the patients were asked to rate their pain based on a 100 mm visual analogue scale (VAS) and complete a Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire assessing both pain and function.

As reported in the Archives of Physical Medicine and Rehabilitation, Luksurapan and Boonhong found that patients in the piroxicam group had significantly greater improvement in scores on the VAS compared with the control group following treatment, with reductions of 47.00 versus 28.57 points.

Using the WOMAC pain subscale, there was also a significantly greater improvement following treatment in the piroxicam compared with the control group, with a score change from baseline of 16.30 versus 8.22 points.

There was a greater reduction in the overall WOMAC score in the piroxicam versus the control group, at a respective 58.04 and 39.17, but this did not quite reach statistical significance.

The researchers note that patient compliance was good and that no major side effects were seen in either group.

They conclude that while these results are promising, "further studies are needed to clarify which parameters of ultrasound would be most efficient to facilitate topical drug diffusion, what ultrasound duration should be used to maximize absorption of the drug, and which topical drugs can be most effectively used for phonophoresis."

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