diclofenac and misoprostol, Arthrotec
Omudhome Ogbru, PharmD
Omudhome Ogbru, PharmD
Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.
Medical and Pharmacy Editor:
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 or Advil), naproxen (Naprosyn), and others that is used to treat inflammation, pain, and fever. Diclofenac, like other NSAIDs works by inhibiting the production of prostaglandins. Prostaglandins are a family of chemicals produced by the cells of the body that promote inflammation, pain, and fever. In addition, they 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.
GENERIC AVAILABLE: No
PREPARATIONS: Tablets (diclofenac/misoprostol): Arthrotec 50 (50 mg/200 g), Arthrotec 75 (75 mg/200 g) .
STORAGE: The tablets should be kept at room temperature, 15-30 C (59-86 F).
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. Administering Arthrotec twice daily is less effective for preventing ulcers. 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 drug information 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 (Eskalith, Lithobid) 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 (Rheumatrex, Trexall) and cyclosporine also may be increased by diclofenac.
Diclofenac may reduce the effectiveness of blood pressure-lowering drugs. Since prostaglandins are important in the control of blood pressure.
Antacids reduce the absorption of misoprostol and may delay absorption of diclofenac. Magnesium-containing antacids worsen misoprostol-associated diarrhea. Therefore, Arthrotec should not be administered with magnesium-containing antacids.
Combining NSAIDs with angiotensin receptor blockers (for example, valsartan [Diovan], losartan [Cozaar], irbesartan [Avapro]) or angiotensin converting enzyme inhibitors (for example, enalapril [Vasotec], captopril [captopril]) in patients who are elderly, volume-depleted (including those on diuretic therapy), or with poor kidney function may result in reduced kidney function, including kidney failure. These effects usually are reversible.
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