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Pharmacy Editor: Jay W. Marks, MD

GENERIC NAME: diclofenac and misoprostol

BRAND NAME: Arthrotec

DRUG CLASS AND MECHANISM: Arthrotec is a combination of diclofenac and misoprostol. Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) similar to ibuprofen (Motrin; Advil), naproxen (Naprosyn), and others. Diclofenac, like other NSAIDs work by inhibiting the production of prostaglandins. Prostaglandins are a related family of chemicals that are produced by the cells of the body and have several important functions. They promote inflammation, pain, and fever, support the function of platelets that are necessary for the clotting of blood, and protect the lining of the stomach from the damaging effects of acid. Prostaglandins are produced by the enzyme cyclooxygenase (Cox). There actually are two Cox enzymes, Cox-1 and Cox-2. Both enzymes produce prostaglandins that promote inflammation, pain, and fever. However, only Cox-1 produces prostaglandins that support platelets and protect the stomach. Diclofenac blocks both Cox enzymes and reduces prostaglandins throughout the body. As a consequence, ongoing inflammation, pain, and fever are reduced. Since prostaglandins that protect the stomach and support platelets and blood clotting also are reduced, NSAIDs can cause ulcers in the stomach and promote bleeding. Misoprostol is a synthetic (man-made) prostaglandin that stimulates secretion of mucus in the gastrointestinal tract. Mucus protects the lining of the stomach from acid. Misoprostol has been shown to reduce the frequency of ulcers of the stomach caused by NSAIDs. Arthrotec was approved by the FDA in December, 1997.

PRESCRIPTION: Yes

GENERIC AVAILABLE: No

PREPARATIONS: Tablets (diclofenac/misoprostol): Arthrotec 50 (50 mg/200 µg) , Arthrotec 75 (75 mg/200 µg) .

STORAGE: The tablets should be kept at room temperature, 15-30°C (59-86°F).

PRESCRIBED FOR: Arthrotec is used for treating signs and symptoms of rheumatoid arthritis or osteoarthritis in patients at risk for developing ulcers from NSAIDs.

DOSING: For osteoarthritis the recommended dose is Arthrotec 50 given three times daily. Patients who cannot tolerate this regimen may be treated with Arthrotec 50 or 75 twice daily. The recommended dose for treating rheumatoid arthritis is Arthrotec 50 given 3-4 times daily. If this regimen is not tolerated, Arthrotec 50 or 75 twice a day may be used. Taking Arthrotec with food may reduce stomach upset. It is recommended that Arthrotec not be taken with alcohol because of the increased risk for ulcers.

DRUG INTERACTIONS: (Please also see the monographs for diclofenac.) Diclofenac is generally used with caution in patients taking blood thinning medications (anticoagulants), such as warfarin (Coumadin), because of the increased risk of bleeding. Patients taking lithium can develop toxic blood levels of lithium because diclofenac may inhibit the elimination of lithium from the body by the kidney. Side effects from methotrexate and cyclosporine also may be increased by diclofenac. Diclofenac may reduce the effectiveness of antihypertensives because it causes or worsens high blood pressure.

PREGNANCY: Since misoprostol can cause abortions, Arthrotec should not be used by women who are pregnant. Avoid pregnancy for 1 month or 1 menstrual cycle after discontinuing Arthrotec.

NURSING MOTHERS: Arthrotec is not recommended for use by nursing mothers.

SIDE EFFECTS: Arthrotec has the side effects of diclofenac and misoprostol. The most common side effects are stomach pain, diarrhea, dyspepsia, nausea and flatulence. Diarrhea and abdominal pain may resolve after 2-7 days. Magnesium containing antacids worsen diarrhea caused by misoprostol. Taking Arthrotec with food and avoiding antacids containing magnesium may reduce the occurrence of diarrhea. Serious side effects include gastrointestinal ulcers and bleeding; liver dysfunction; severe skin reactions. Severe bronchospasms may occur in patients with aspirin-sensitive asthma. Like other NSAIDS Arthrotec may cause heart attacks and strokes; accumulation of fluid and worsen heart failure; cause or worsen hypertension and kidney failure.

References Facts and Comparisons 4.0. Online Edition Arthrotec prescribing information. Pfizer Inc., 2005

Reference: FDA Prescribing Information

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