Diclofenac sodium, originally marketed as Voltaren in the United States, is a nonsteroidal anti-inflammatory drug, or NSAID, which is used to reduce the swelling, pain, redness and warmth that accompany inflammatory conditions, such as arthritis. The U.S. Food and Drug Administration first approved a tablet form of diclofenac in July 1988. A topical preparation, designed to alleviate arthritis symptoms in your extremities, received FDA approval in October 2007.
Diclofenac Blocks COX Enzymes
Like other NSAIDs, diclofenac exerts its anti-inflammatory effects by interfering with the activity of cyclooxygenase, or COX, enzymes in your cells. COX enzymes convert fatty acids to prostaglandins, which dilate blood vessels, sensitize nerve endings to pain and stimulate immune cells to produce inflammatory chemicals called cytokines. Blockade of COX enzymes reduces the synthesis of prostaglandins and, thus, the symptoms of inflammation. According to a 2007 review in "Prostaglandins and Other Lipid Mediators," diclofenac preferentially blocks a specific enzyme called COX-2, which helps to preserve a prostaglandin that protects the lining of your stomach.
Diclofenac Sodium for Arthritis
According to "Physicians' Desk Reference," diclofenac sodium is indicated "for relief of signs and symptoms of osteoarthritis and rheumatoid arthritis." It is also recommended for treating people with ankylosing spondylitis, a form of arthritis that causes fusion of the spine. Osteoarthritis primarily affects weight-bearing joints, such as the knees, hips and spinal column, with the hands involved to a lesser extent. Rheumatoid arthritis is typically more inflammatory than osteoarthritis and causes pain, swelling and deformity in the hands and wrists, feet, elbows, and ankles, although any joint can be involved.
Diclofenac Sodium Side Effects
Although diclofenac preferentially affects the COX-2 enzyme, it still impairs production of the stomach's protective prostaglandins. Therefore, stomach ulceration and gastrointestinal bleeding are among the drug's most worrisome side effects. This is less of a concern with the topical gel form of diclofenac. Other potential side effects include nausea, heartburn, abdominal pain, flatulence, dizziness, fluid retention, itching, headaches and an increased tendency to bleed. Diclofenac is metabolized by your liver and excreted through your kidneys, so this medication can cause liver or kidney damage, especially for people who already have liver or kidney disease. The topical preparation can cause many of the same side effects, though to a lesser degree, as well as localized burning or skin irritation.
Diclofenac Drug Interactions
Diclofenac sodium interferes with your blood's clotting ability, so it will enhance the effects of aspirin, warfarin and other drugs that increase bleeding. Diclofenac may also interfere with diuretics, such as furosemide, and blood pressure medications, such as ACE inhibitors. If you are receiving chemotherapy drugs, such as methotrexate or cyclosporine, the toxicity of these drugs could be increased by diclofenac.
Considerations
Diclofenac sodium is a useful agent for relieving the symptoms of arthritis, and a topical form may help to reduce the likelihood of side effects. Both oral and topical forms are available by prescription in the United States, although some countries allow over-the-counter sales of this medication. If you suffer from arthritis, your doctor or pharmacist can offer more detailed information about the risks and benefits of diclofenac sodium and help you decide if this drug is appropriate for you.
References
- Drugs.com: Voltaren Gel Approval History
- "Prostaglandins and Other Lipid Mediators"; Pharmacodynamic of Cyclooxygenase Inhibitors in Humans; M.L. Capone, et al.; January 2007
- Physicians' Desk Reference, 60th Edition: Voltaren; Lori Murray, Senior Editor; 2006
