| Item |
Information |
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Drug Groups
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approved; investigational |
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Description
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Indomethacin is a non-steroidal antiinflammatory agent (NSAIA) with antiinflammatory, analgesic and antipyretic activity. Its pharmacological effect is thought to be mediated through inhibition of the enzyme cyclooxygenase (COX), the enzyme responsible for catalyzes the rate-limiting step in prostaglandin synthesis via the arachidonic acid pathway. |
| Indication |
For moderate to severe rheumatoid arthritis including acute flares of chronic disease, ankylosing spondylitis, osteoarthritis, acute painful shoulder (bursitis and/or tendinitis) and acute gouty arthritis. |
| Pharmacology |
Indomethacin, a NSAIA, with analgesic and antipyretic properties exerts its pharmacological effects by inhibiting the synthesis of prostaglandins involved in pain, fever, and inflammation. Indomethacin inhibits the catalytic activity of the COX enzymes, the enzymes responsible for catalyzing the rate-limiting step in prostaglandin synthesis via the arachidonic acid pathway. Indomethacin is known to inhibit two well-characterized isoforms of COX, COX-1 and COX-2, with greater selectivity for COX-1. COX-1 is a constitutively expressed enzyme that is involved in gastric mucosal protection, platelet and kidney function. It catalyzes the conversion of arachidonic acid to prostaglandin (PG) G2 and PGG2 to PGH2. COX-1 is involved in the synthesis pathways of PGE2, PGD2, PDF2a, PGI2 (also known as prostacyclin) and thromboxane A2 (TXA2). COX-2 is constitutively expressed and highly inducible by inflammatory stimuli. It is found in the central nervous system, kidneys, uterus and other organs. It also catalyzes the conversion of arachidonic acid to PGG2 and PGG2 to PGH2. In the COX-2-mediated pathway, PGH2 is subsequently converted to PGE2 and PGI2 (also known as prostacyclin). PGE2 is involved in mediating inflammation, pain and fever. Decreasing levels of PGE2 leads to decreased inflammation. |
| Toxicity |
The following symptoms may be observed following overdosage: nausea, vomiting, intense headache, dizziness, mental confusion, disorientation, or lethargy. There have been reports of paresthesias, numbness, and convulsions. The oral LD50 of indomethacin in mice and rats (based on 14 day mortality response) was 50 and 12 mg/kg, respectively. |
| Affected Organisms |
| • |
Humans and other mammals |
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| Biotransformation |
Hepatic. |
| Absorption |
Bioavailability is approximately 100% following oral administration and 80–90% following rectal administration. |
| Half Life |
4.5 hours |
| Protein Binding |
97% |
| Elimination |
Indomethacin is eliminated via renal excretion, metabolism, and biliary excretion. |
| References |
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Akbarpour F, Afrasiabi A, Vaziri ND: Severe hyperkalemia caused by indomethacin and potassium supplementation. South Med J. 1985 Jun;78(6):756-7.
[Pubmed]
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HART FD, BOARDMAN PL: INDOMETHACIN: A NEW NON-STEROID ANTI-INFLAMMATORY AGENT. Br Med J. 1963 Oct 19;2(5363):965-70.
[Pubmed]
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Lum GM, Aisenbrey GA, Dunn MJ, Berl T, Schrier RW, McDonald KM: In vivo effect of indomethacin to potentiate the renal medullary cyclic AMP response to vasopressin. J Clin Invest. 1977 Jan;59(1):8-13.
[Pubmed]
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Phelan KM, Mosholder AD, Lu S: Lithium interaction with the cyclooxygenase 2 inhibitors rofecoxib and celecoxib and other nonsteroidal anti-inflammatory drugs. J Clin Psychiatry. 2003 Nov;64(11):1328-34.
[Pubmed]
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Ragheb M: The clinical significance of lithium-nonsteroidal anti-inflammatory drug interactions. J Clin Psychopharmacol. 1990 Oct;10(5):350-4.
[Pubmed]
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