Osteoarthritis

Microspheres keep IA steroids in place


A single intra-articular injection of a novel extended-release triamcinolone acetonide formulation (FX006) has been shown to reduce pain in knee osteoarthritis for up to three months.

The phase 3 trial of the microsphere-based formulation was compared to saline injections and a standard crystalline suspension of the steroid in almost 500 patients across 38 sites inclding Australian centres.

The trial found FX006 afforded a 50% improvement in an average daily pain (ADP) intensity score compared to saline at week 12 but no significant improvement compared to the standard version of the steroid.

However FX006 performed more favourably than the standard triamcinolone acetonide on WOMAC sub-scale scores for pain, stiffness and physical function, and on the KOOS-QOL scale.

Adverse events were similar across the three arms of the study and mostly low grade. There was no evidence of a clinically relevant foreign-body response seen in some other studies with microsphere formulations.

Lead author Professor Philip Conaghan, from the Leeds Institute of Rheumatic and Musculoskeletal Medicine, told the limbic conventional intra-articular steroids were generally effective for 2 to 4 weeks.

“Although both steroid preparations show benefit at three months, this is on the average daily pain scale which is not a tool we’ve used much in clinical trials and is probably not as responsive as the WOMAC scale which most clinicians will be familiar with.”

“On the WOMAC pain scale the new preparation clearly separates from existing corticosteroid and there is a benefit compared to conventional steroid injection.”

He added that other data has shown no post-injection change to systemic sugar levels in patients with diabetes, which further suggests the new formulation stays within the joint.

“I think this paper provides evidence of a new clinically effective steroid formulation with benefits up to three months.”

However he said steroids were only one part of the treatment package for osteoarthritis, which should also include muscle strengthening.

A Commentary in the Journal of Bone and Joint Surgery said the idea of an extended-release corticosteroid formulation was ‘quite attractive’.

However the lack of a significant difference between the extended-release formulation and the current standard of care in the primary outcome was not convincing despite some of the other end points looking promising.

“The likely increased cost of FX006 over TAcs may not sufficiently justify its use in clinical practice,” the Commentary said.

“A follow-up trial with a primary head-to-head comparison of FX006 and TAcs could potentially make a major impact on clinical practice.”

Co-author Professor David Hunter, from the University of Sydney, told the limbic the limited duration of treatment response of traditional intra-articular steroids had dampened enthusiasm for their efficacy.

“The intent of a sustained duration release product is to prolong the therapeutic effect. In meta-analyses of FX006, it provides symptom relief and separation from placebo out to 12 weeks.”

He said FX006 has only recently gained regulatory approval from the FDA and was not yet available in Australia.

 

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