CYCLOOXYGENASE-2 (COX-2) INHIBITORS.MODE OF ACTION Selective cyclooxygenase-2 inhibitor Prevents the production of prostaglandins, resulting in anti-inflammatory effects. Cyclooxygenase (COX) exists as two isoenzymes, COX-1 and COX-2. The inhibition of COX-1 activity has been associated with the gastrointestinal toxicity of the traditional nonsteroidal anti-inflammatory drugs Nonsteroidal Anti-Inflammatory Drugs Definition Nonsteroidal anti-inflammatory drugs are medicines that relieve pain, swelling, stiffness, and inflammation. (NSAIDs), while COX-2 inhibition is responsible for the anti-inflammatory effects of the NSAIDs. CONTRAINDICATIONS Known hypersensitivity to the particular COX-2 inhibitor, or hypersensitivity reactions to aspirin or other NSAIDs. For celecoxib, hypersensitivity to sulfonamides Sulfonamides Definition Sulfonamides are medicines that prevent the growth of bacteria in the body. Purpose Sulfonamides are used to treat many kinds of infections caused by bacteria and certain other microorganisms. . Active GI bleeding or ulceration. Use caution in patients with renal dysfunction. Pregnancy Category C Pregnancy category C No adequate human or animal studies; or adverse fetal effects in animal studies, but no available human data. Mentioned in: Antianxiety Drugs . ADVERSE EFFECTS Gastrointestinal effects, including ulceration, bleeding, and inflammation of the GI tract, may occur without warning symptoms. Dyspepsia, heartburn, gastritis are more common adverse effects. Dizziness, drowsiness, and headache have been reported. Depression and other psychiatric disorders, epilepsy, and Parkinson's disease may be exacerbated. Asthma may be exacerbated, and bronchospasm bronchospasm /bron·cho·spasm/ (brong´ko-spazm) bronchial spasm; spasmodic contraction of the smooth muscle of the bronchi, as in asthma. bron·cho·spasm n. has been reported. Hypertension and fluid retention may be worsened. Any NSAID NSAID: see nonsteroidal anti-inflammatory drug. may worsen renal function, as these drugs are renally excreted. NSAIDs may affect hepatic function, and should be used with caution in patients with liver disease. DRUG-DRUG INTERACTIONS Use caution when prescribing any NSAID, including the COX-2 inhibitors, to a patient taking warfarin warfarin (wôr`fərĭn), anticoagulant used to treat blood clots. In large doses it causes bleeding. Warfarin, mixed with bait, is used in rodent control. warfarin Anticoagulant drug, marketed as Coumadin. therapy. The INR INR In currencies, this is the abbreviation for the Indian Rupee. Notes: The currency market, also known as the Foreign Exchange market, is the largest financial market in the world, with a daily average volume of over US $1 trillion. should be monitored closely after initiation of COX-2 therapy. The effectiveness of antihypertensives and diuretics may be decreased with concurrent COX-2 inhibitor use. Concurrent aspirin therapy may increase risk of gastrointestinal ulceration. Lithium levels may be increased. Methotrexate methotrexate, drug used in halting the growth of actively proliferating tissues. Introduced in the 1950s, it is used in the treatment of leukemia, psoriasis, and non-Hodgkin's lymphoma. levels may be increased with rofecoxib. Rifampin rifampin (rĭfăm`pĭn), antibiotic used in the treatment of tuberculosis. It is also used to eliminate the meningococcus microorganism from carriers and to treat leprosy, or Hansen's disease. may decrease rofecoxib efficacy due to decreased plasma concentrations. DRUG-FOOD INTERACTIONS The COX-2 inhibitors, especially in higher doses, should generally be taken with meals to reduce GI upset. PRODUCTS AVAILABLE Celecoxib (Celebrex) Rofecoxib (Vioxx) RECOMMENDED DOSES Celecoxib Osteoarthritis: 200 mg/day in a single or divided dose Rheumatoid arthritis: 100 to 200 mg BID Familial adenomatous polyposis familial adenomatous polyposis Familial polyposis An AD condition affecting ±50,000–US, characterized by progressive development of hundreds of adenomatous colorectal polyps; progression to cancer Molecular pathology APC : 400 mg BID with food Rofecoxib Osteoarthritis: start at 12.5 mg QD, may increase to 25 mg QD Acute pain or primary dysmenorrhea: 50 mg QD, should not exceed 5 days of therapy at this dose. DOSAGE FORMS AVAILABLE Celecoxib: 100 mg and 200 mg capsules Rofecoxib: 12.5 mg, 25 mg, and 50 mg tablets, and 12.5 mg/5 mL and 25 mg/5 mL suspension MANUFACTURERS Celecoxib: Searle Rofecoxib: Merck OTHER POINTS OF INTEREST The COX-2 inhibitors should not be used late in pregnancy, as they may cause premature closure of the ductus arteriosus. References (1.) Hutchison TA, Shahan DR, Anderson ML (Eds): DRUGDEX System. MICROMEDEX, Inc., Englewood, Colorado (Edition expires 12/2000) (2.) Hebel SK, Katstrup EK (Eds): Drug Facts and Comparisons. St. Louis, MO (2001) |
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