Lower-Dose Diclofenac Improves Pain in Osteoarthritis

This is for our providers treating chronic pain patients.

For patients with osteoarthritis, a formulation of the nonsteroidal anti-inflammatory drug (NSAID) diclofenac, developed with SoluMatrix fine-particle technology (Zorvolex, Iroko Pharmaceuticals), improves health-related quality of life, physical function, and pain, according to a phase 3 open-label study.

“We re-engineered diclofenac to enable lower doses to be used, in line with the black box warning to use the lowest effective dose of NSAIDs for the shortest duration of time,” study researcher Clarence Young, MD, an employee of Iroko Pharmaceuticals, explained here at the American College of Rheumatology 2014 Annual Meeting.

“We saw improvement in all physical domains over the course of the study,” he reported. “This is a promising treatment for osteoarthritis pain.”

The fine-particle technology is a patented process that creates submicron drug particles that are smaller than the conventional drug particles.

The new formulation is an important addition to the armamentarium, because it “allows better absorption so you can use a lower dose, and it is better tolerated with similar efficacy,” study researcher Vibeke Strand, MD, from Stanford University in Palo Alto, California said. However, she noted, these results have not been “proven in a head-to-head comparison.”

The 602 patients enrolled in the study were diagnosed with hip or knee osteoarthritis and reported chronic NSAID and/or acetaminophen use. Most were newly enrolled, but 141 patients were rolled over from a 12-week study of the diclofenac formulation.

All patients were 40 years or older, and 45% were older than 60 years. Mean age was 59.7 years, 61.9% of the participants were women, and 84.2% were white.

Clinically Meaningful Improvement
Dr. Young and his team used the SF-36 Health Survey, version 2, to assess health-related quality-of-life outcomes in patients at baseline and at weeks 12, 24, 32, 40, 48, and 52.

All patients were treated with a starting dose of diclofenac 35 mg twice daily, and about 50% of patients remained on that regimen for the duration of the study. Of the 302 patients whose dosage was increased to 3 times daily, about 40% remained on that regimen.
The 52-week study was completed by 360 patients (59.8%).

Clinically meaningful improvement, defined as an increase in the mean physical component score of the SF-36 of at least 2.5, was significant at week 12 and at all time points up to 52 weeks (P < .0001).
Significant improvement from baseline was also seen for domains of the physical component score, including physical functioning (P < .0001), physical role (P < .0001), body pain (P < .0001), vitality (P < .0001), social functioning (P < .0001), and emotional role (P = .0004).

“This formulation is an advance in treating patients with osteoarthritis pain, allowing lower doses of NSAIDs to be used,” said Roland Staud, MD, from the University of Florida in Gainesville, who was not involved in the study.

“Side effects of treatments are mainly dose-related. Patients know that, and they like to use the lowest possible dose. Many of them do pill-splitting and other maneuvers to try to get the desired effects with less drug,” he explained.