indication

For relief and management of osteoarthritis (OA), rheumatoid arthritis (RA), ankylosing spondylitis, acute pain, primary dysmenorrhea and oral adjunct to usual care for patients with familial adenomatous polyposis

pharmacology

Celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, is classified as a nonsteroidal anti-inflammatory drug (NSAID). Celecoxib is used to treat rheumatoid arthritis, osteoarthritis, and familial adenomatous polyposis (FAP). Because of its lack of platelet effects, celecoxib is not a substitute for aspirin for cardiovascular prophylaxis. It is not known if there are any effects of celecoxib on platelets that may contribute to the increased risk of serious cardiovascular thrombotic adverse events associated with the use of celecoxib. Inhibition of PGE2 synthesis may lead to sodium and water retention through increased reabsorption in the renal medullary thick ascending loop of Henle and perhaps other segments of the distal nephron. In the collecting ducts, PGE2 appears to inhibit water reabsorption by counteracting the action of antidiuretic hormone.

mechanism of action

The mechanism of action of celecoxib is believed to be due to inhibition of prostaglandin synthesis. Unlike most NSAIDs, which inhibit both types of cyclooxygenases (COX-1 and COX-2), celecoxib is a selective noncompetitive inhibitor of cyclooxygenase-2 (COX-2) enzyme. It binds with its polar sulfonamide side chain to a hydrophilic side pocket region close to the active COX-2 binding site. Both COX-1 and COX-2 catalyze the conversion of arachidonic acid to prostaglandin (PG) H2, the precursor of PGs and thromboxane.

toxicity

Symptoms of overdose include breathing difficulties, coma, drowsiness, gastrointestinal bleeding, high blood pressure, kidney failure, nausea, sluggishness, stomach pain, and vomiting.

biotransformation

Hepatic. Celecoxib metabolism is primarily mediated via cytochrome P450 2C9. Three metabolites, a primary alcohol, the corresponding carboxylic acid and its glucuronide conjugate, have been identified in human plasma. These metabolites are inactive as COX-1 or COX-2 inhibitors.

absorption

Well absorbed in the gastrointestinal tract. When taken with a high fat meal, peak plasma levels are delayed for about 1 to 2 hours with an increase in total absorption (AUC) of 10% to 20%.

half life

Approximately 11 hours.

route of elimination

Celecoxib is eliminated predominantly by hepatic metabolism with little (<3%) unchanged drug recovered in the urine and feces.

drug interactions

Acenocoumarol: Celecoxib may increase the anticoagulant effect of acenocoumarol.

Anisindione: Celecoxib may increase the anticoagulant effect of anisindione.

Colesevelam: Bile acid sequestrants may decrease the absorption of Nonsteroidal Anti-Inflammatory Agents. Monitor for decreased serum concentrations/therapeutic effects of nonsteroidal anti-inflammatory agents (NSAID) if coadministered with bile acid sequestrants. Separating the administration of doses by 2 or more hours may reduce (but not eliminate) the risk of interaction. The manufacturer of colesevelam recommends that drugs should be administered at least 1 hour before or 4 hours after colesevelam.

Dicumarol: Celecoxib may increase the anticoagulant effect of dicumarol.

Fluconazole: Fluconazole may increase the effect of celecoxib.

Lithium: The COX-2 inhibitor increases serum levels of lithium

Rifampin: Rifampin, a strong CYP2C9 inducer, may decrease the serum levels of celecoxib by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects if rifampin is initiated, discontinued or dose changed.

Telmisartan: Concomitant use of Telmisartan and Celecoxib may increase the risk of acute renal failure and hyperkalemia. Monitor renal function at the beginning and during treatment.

Timolol: The NSAID, Celecoxib, may antagonize the antihypertensive effect of Timolol.

Tolbutamide: Tolbutamide, a strong CYP2C9 inhibitor, may decrease the metabolism and clearance of Celecoxib. Consider alternate therapy or monitor for changes in Celecobix therapeutic and adverse effects if Tolbutamide is initiated, discontinued or dose changed.

Trandolapril: The NSAID, Celecoxib, may reduce the antihypertensive effect of Trandolapril. Consider alternate therapy or monitor for changes in Trandolapril efficacy if Celecoxib is initiated, discontinued or dose changed.

Treprostinil: The prostacyclin analogue, Treprostinil, may increase the risk of bleeding when combined with the NSAID, Celecoxib. Monitor for increased bleeding during concomitant thearpy.

Tretinoin: The moderate CYP2C8 inhibitor, Celecoxib, may decrease the metabolism and clearance of oral Tretinoin. Monitor for changes in Tretinoin effectiveness and adverse/toxic effects if Celecoxib is initiated, discontinued to dose changed.

Vilazodone: Selective Serotonin Reuptake Inhibitors may enhance the antiplatelet effect of NSAID (COX-2 Inhibitor). To minimize the risk of bleeding associated with this combination, consider using alternative analgesics, when appropriate, and/or addition of an gastroprotective agent, such as a proton pump inhibitor for the time that combined selective serotonin reuptake inhibitor (SSRIs) and nonsteroidal anti-inflammatory drugs (NSAIDs) is necessary.

Warfarin: Celecoxib may increase the anticoagulant effect of warfarin.