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FDA Approves Low-Dose Anti-Inflammatory for Arthritis Pain

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25 August 2014. Iroko Pharmaceuticals LLC in Philadelphia says the U.S. Food and Drug Administration approved its low-dose formulation of the nonsteroidal anti-inflammatory drug diclofenac to treat pain from osteoarthritis. FDA in October 2013 already approved this drug, marketed under the name Zorvolex, as a treatment for mild to moderate pain in adults.

Osteoarthritis is the most common form of arthritis, where cartilage that cushions the joints breaks down, causing bones to rub together resulting in stiffness and pain, affecting some 27 million Americans according to the Arthritis Foundation. Symptoms often appear gradually and become worse with age, but are aggravated by overuse, obesity, previous injuries, and in some cases genetics. Treatments for osteoarthritis usually aim at relieving pain, since no cure is yet found.

Nonsteroidal anti-inflammatory drugs or NSAIDs are the most prescribed medications for relieving arthritis pain, with some common over-the-counter NSAIDs becoming household names, such as aspirin and ibuprofen. NSAIDs prevent two types of enzymes called cyclooxygenases from working. One form of cyclooxygenase is produced when joints become hurt or inflamed, while the other protects the stomach lining from harsh digestive acids. As a result, NSAIDs can relieve inflammation and pain in the joints, but can also cause stomach upset and bleeding.

Because of these and other adverse effects, FDA in 2007 prepared a medication guide including a recommendation that NSAIDs be used in the lowest dose possible and the shortest time needed. In response to that recommendation, Iroko developed its formulation of diclofenac, an NSAID already prescribed for various pain conditions, including osteoarthritis and rheumatoid arthritis.

The company’s formulation, however, is designed to work in lower dosages. Iroko obtained a license to apply a manufacturing technology developed by iCeutica, also in Philadelphia that mills drug particles down to sub-micron (less than 1 millionth of a meter) size. Iroko has exclusive rights to apply iCeutica’s technology for pain medications. In the case of Zorvolex, Iroko’s particles are 20 times smaller than the original, providing a larger surface area to expose diclofenac for pain relief, thus making lower doses possible.

Iroko says FDA’s approval of Zorvolex was influenced by results of a late-stage clinical trial testing the drug against a placebo among 305 adults, age 40 and higher, with hip or knee pain caused by osteoarthritis. Patients in the trial were randomly assigned to receive 35 milligram capsules of Zorvolex two or three times a day, or a placebo for 12 weeks.

The trial looked primarily at scores on a standard index of reported osteoarthritis pain at the beginning and end of the 12-week period. Results showed patients taking Zorvolex three times a day were more likely to report more pain relief after 12 weeks than those taking the placebo. Patients taking the drug twice a day also reported more pain relief than the placebo group, but the differences were not large enough to be statistically reliable. The most common adverse effects among those taking Zorvolex were  diarrhea, headache, nausea, and constipation.

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