Diclofenac sodium in the treatment of osteoarthritis

Abstract

Diclofenac is a well-tolerated, traditional nonsteroidal anti-inflammatory drug that has been shown to be very effective for the treatment of osteoarthritis. Serendipitously, diclofenac has been shown to be relatively selective for cyclooxygenase-2; perhaps due to that fact, it has proven to be well tolerated. Tolerance and utility have been augmented with a variety of formulations, including extended-release tablets, a combination tablet with misoprostol, a suppository preparation and a topically absorbed solution. Sodium diclofenac tablets are available in 25 and 50 mg units, the extended-release tablets are available in 75 and 100 mg units, and the suppositories in 50 and 100 mg units. The usual daily dose ranges from 75 to 150 mg, ingested as two or three divided doses. The drug is a phenylacetic acid derivative. Although it is completely absorbed, only 60% is thought to reach the systemic circulation due to first-pass metabolism. The area under the plasma concentration curve is proportional to the dose in the range of 25–150 mg.