FDA Approves Lower-Dose Formulation of Diclofenac

The US Food and Drug Administration (FDA) has approved Zorvolex capsules, a new formulation of the NSAID diclofenac, for the treatment of mild to moderate acute pain in adults, according to an announcement from Iroko Pharmaceuticals. The drug was approved at a 20% lower dosage strength than currently available formulations of diclofenac.

The lower dose is achieved by delivering diclofenac in submicron particles approximately 20 times smaller than existing formulations, which dissolve more quickly. The goal is to reduce the risk of serious adverse events by achieving similar pain relief at a lower dose.

A statement by the manufacturer says that FDA approval was based on a Phase 3 multi-center, randomized study published last month in PostGraduate Medicine, in which 428 patients scheduled for bunion removal were randomized for treatment with Zorvolex, celecoxib, or placebo.  Those who received 18 mg or 35 mg of Zorvolex three times a day (the currently recommended dosage) experienced early and sustained significant pain relief on a visual analog pain scale, compared to placebo subjects. Unlike celecoxib, the higher dose of Zorvolex achieved pain relief within 30 minutes.

(The celecoxib arm was included in the study for general comparison with another NSAID, Iroko chief medical officer Clarence Young MD said in an interview. But because the study was not designed or powered to compare the two drugs, although comparative information does appear in the publication it is not provided in the FDA-approved label wording.)