Molecule

Drug Groups

approved; investigational

Description

Etodolac is a non-steroidal anti-inflammatory drug (NSAID) with anti-inflammatory, analgesic and antipyretic properties. Its therapeutic effects are due to its ability to inhibit prostaglandin synthesis. It is indicated for relief of signs and symptoms of rheumatoid arthritis and osteoarthritis.

Indication

For acute and long-term management of signs and symptoms of osteoarthritis and rheumatoid arthritis, as well as for the management of pain.

Pharmacology

Etodolac is an anti-inflammatory agent with analgesic and antipyretic properties. It is used to treat osteoarthritis, rheumatoid arthritis and control acute pain. The therapeutic effects of etodolac are achieved via inhibition of the synthesis of prostaglandins involved in fever, pain, swelling and inflammation. Etodolac is administered as a racemate. As with other NSAIDs, the S-form has been shown to be active while the R-form is inactive. Both enantiomers are stable and there is no evidence of R- to S- conversion in vivo.

Toxicity

Selective COX-2 inhibitors have been associated with increased risk of serious cardiovascular events (e.g. myocardial infarction, stroke) in some patients. Current data is insufficient to assess the cardiovascular risk of etodolac. Etodolac may increase blood pressure and/or cause fluid retention and edema. Risk of GI toxicity including bleeding, ulceration and perforation. Risk of direct renal injury, including renal papillary necrosis. Anaphylactoid and serious skin reactions (e.g. exfoliative dermatitis, Stevens-Johnson syndrome, toxic epidermal necrolysis) have been reported. Common adverse events include abdominal pain, constipation, diarrhea, dyspepsia, flatulence, GI bleeding, GI perforation, nausea, peptic ulcer, vomiting, renal function abnormalities, anemia, dizziness, edema, liver function test abnormalities, headache, prolonged bleeding time, pruritus, rash, tinnitus. Symptoms of overdose include lethargy, drowsiness, nausea, vomiting, and epigastric pain.

Affected Organisms

Biotransformation

Etodolac is extensively metabolized in the liver. Renal elimination of etodolac and its metabolites is the primary route of excretion (72%). Metabolites found in urine (with percents of the administered dose) are: unchanged etodolac (1%), etodolac glucuronide (13%), hydroxylated metabolites (6-, 7-, and 8-OH; 5%), hydroxylated metabolite glucuronides (20%), and unidentified metabolites (33%). Fecal excretion accounts for 16% of its elimination.

Absorption

Based on mass balance studies, the systemic bioavailability of etodolac from either the tablet or capsule formulation is at least 80%.

Half Life

Terminal t_1/2, 7.3 ± 4.0 hours. Distribution t_1/2, 0.71 ± 0.50 hours

Protein Binding

> 99% bound, primarily to albumin

Elimination

It is not known whether etodolac is excreted in human milk; however, based on its physical-chemical properties, excretion into breast milk is expected. Etodolac is extensively metabolized in the liver. The hydroxylated-etodolac metabolites undergo further glucuronidation followed by renal excretion and partial elimination in the feces (16% of dose). Approximately 1% of a etodolac dose is excreted unchanged in the urine with 72% of the dose excreted into urine as parent drug plus metabolite.

Distribution

* 390 mL/kg

Clearance

* Oral cl=49.1 mL/h/kg [Normal healthy adults]
* Oral cl=49.4 mL/h/kg [Healthy males (18-65 years)]
* Oral cl=35.7 mL/h/kg [Healthy females (27-65 years)]
* Oral cl=45.7 mL/h/kg [Eldery (>65 years)]
* Oral cl=58.3 mL/h/kg [Renal impairement (46-73 years)]
* Oral cl=42.0 mL/h/kg [Hepatic impairement (34-60 years)]

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