The use of hyaluronic acid (HA) in osteoarthritis was discussed at a satellite symposium sponsored by Pharmascience and Fidia. It was concluded that HA was effective in terms of pain relief of symptoms of osteoarthritis (OA) and may potentially be a structure modifying drug.
Dr SIMON DONNELLY (rheumatology department, Whipps Cross hospital, London) said that OA of the knee was common, with a prevalence of 20-25 per cent in 45-year-olds.
He reported the results of a study of 100 patients with OA of the knee who were treated with five weekly injections of intra-articular HA. There was a significant difference in favour of HA in terms of pain on walking at week five which persisted to six months, Dr Donnelly said. HA was an "effective symptomatic treatment" that gave sustained pain relief in two-thirds of patients. The most common adverse reactions were local injection site reactions which occurred with equal frequency in the HA and placebo groups. The reactions tended to be short-lived (12-24 hours) with some swelling, he added.
Dr ROY ALTMAN (professor of medicine, University of Miami, US) described a trial of 495 patients that suggested HA was superior to naproxen and placebo in patients with OA of the knee. After 26 weeks, 48 per cent of patients who had received HA were pain-free or had slight pain compared with 33 per cent of the placebo group and 39 per cent of the naproxen group.
Dr Altman concluded that HA produced sustained pain relief, improved function and was at least as effective as naproxen with fewer side effects. There were several hypotheses as to the mechanism of action of HA, he said. It might act as a mechanical barrier but it remained in the joint for less than a week and its effects lasted for months. Alternative suggestions were that it had an anti-inflammatory action or bound to neuropeptides, he said.
The mechanism of action was also discussed by Dr XAVIER AYRAL (department of rheumatology, Réne Descarte university, Paris, France). Studies had provided evidence of a structure modifying effect of HA in OA, he said. They suggested that HA had several effects, including preservation of chondrocyte vitality and cartilage structure and a reduction of synovial cell proliferation.
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