Medications and Drugs

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Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD

GENERIC NAME: diclofenac

BRAND NAMES: Voltaren, Cataflam, Voltaren-XR

DRUG CLASS AND MECHANISM: Diclofenac belongs to a class of drugs called non-steroidal anti-inflammatory drugs (NSAIDs) that are used for the treatment of mild to moderate pain, fever, and inflammation. Other members of this class include ibuprofen (Motrin), indomethacin (Indocin), nabumetone (Relafen), naproxen (Aleve) and several others. NSAIDs work by reducing the production of prostaglandins, chemicals that cause pain, fever and inflammation. NSAIDs block the enzyme that makes prostaglandins (cyclooxygenase), resulting in lower production of prostaglandins. As a consequence, inflammation, pain and fever are reduced. Since the response to different NSAIDs varies from patient to patient, it is not unusual for a doctor to try different NSAIDs for any given condition. The FDA approved diclofenac in July 1998.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets (delayed release): 25, 50, and 75 mg. Tablets (immediate release): 50 mg. Tablets (extended release): 100mg

STORAGE: Diclofenac should not be stored above 30°C (86°F) and should be protected from moisture.

PRESCRIBED FOR: Diclofenac is used primarily for the treatment of inflammation and pain caused by conditions such as rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis. It is also effective in treating soft tissue inflammations due to tendinitis and bursitis, and treating dysmenorrhea (menstrual cramps).

DOSING: Diclofenac should be taken with food to reduce stomach upset. The recommended dose for most conditions is 100-200 mg daily. Dosing intervals depend on the diclofenac formulation used and the condition being treated.

DRUG INTERACTIONS: Diclofenac, like other NSAIDs is associated with several suspected or probable interactions that affect the action of other drugs. Some examples are discussed below.

Diclofenac may increase the blood levels of lithium (Eskalith) by reducing the excretion of lithium by the kidneys. Increased levels of lithium may lead to lithium toxicity.

Diclofenac may reduce the blood pressure lowering effects of blood pressure medications. This may occur because prostaglandins play a role in the regulation of blood pressure.

When diclofenac is used in combination with aminoglycoside antibiotics [for example, gentamicin (Garamycin)] the blood levels of the aminoglycoside may increase, presumably because the elimination of aminoglycosides from the body is reduced. This may lead to more aminoglycoside-related side effects.

Individuals taking oral blood thinners or anticoagulants [for example, warfarin (Coumadin)] should avoid diclofenac because diclofenac also thins the blood, and excessive blood thinning may lead to bleeding.

Combining NSAIDs with methotrexate (Rheumatrex, Trexall) may reduce the elimination of methotrexate from the body and result in increased side effects from methotrexate.

PREGNANCY: Like other NSAIDs, diclofenac is generally avoided during pregnancy because it may affect the cardiovascular system of the fetus.

NURSING MOTHERS: It is not known whether diclofenac is excreted in breast milk.

SIDE EFFECTS: The most common side effects of diclofenac involve the gastrointestinal system. It can cause ulcerations, abdominal burning, pain, cramping, nausea, gastritis, and even serious gastrointestinal bleeding and liver toxicity. Sometimes, stomach ulceration and bleeding can occur without any abdominal pain. Black tarry stools, weakness, and dizziness upon standing may be the only signs of internal bleeding. Rash, kidney impairment, ringing in the ears, and lightheadedness are also seen. People who are allergic to other NSAIDs should not use diclofenac. NSAIDs reduce the flow of blood to the kidneys and impair function of the kidneys. The impairment is most likely to occur in patients with already reduced kidney function or congestive heart failure, and use of NSAIDs in these patients should be done cautiously. Individuals with asthma are more likely to experience allergic reactions to diclofenac and other NSAIDs. Fluid retention, blood clots, heart attacks, hypertension and heart failure have also been associated with the use of NSAIDs.

Reference: FDA Prescribing Information

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