Indomethacin (indomethacin sodium)

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Last reviewed · Source: First Databank (FDB) drug data

Overview

Indomethacin is a nonsteroidal anti-inflammatory agent (NSAIA) that also exhibits analgesic and antipyretic activity.

Indomethacin has pharmacologic actions similar to those of other prototypical nonsteroidal anti-inflammatory agents (NSAIAs). The drug exhibits anti-inflammatory, analgesic, and antipyretic activity. The exact mechanisms have not been clearly established, but many actions appear to be associated principally with inhibition of prostaglandin synthesis.

Indomethacin inhibits the synthesis of prostaglandins in body tissues by inhibiting cyclooxygenase-1 (COX-1) and -2 (COX-2). Prostaglandins are inflammatory mediators and in animal models have been shown to sensitize afferent nerves and potentiate the activity of bradykinin in inducing pain.

In newborn infants with certain congenital heart defects, prostaglandin E1 dilates the ductus arteriosus, and E-type prostaglandins have been shown to maintain the patency of the ductus. Following IV administration of indomethacin in premature neonates with patent ductus arteriosus, a transient decrease in cerebral blood flow velocity and in cerebral blood flow were observed; similar decreases in mesenteric blood flow and velocity have been observed. The clinical importance of these effects has not been established.

Following oral administration of indomethacin conventional capsules, bioavailability is virtually 100%, with 90% of a single dose being absorbed within 4 hours. When administered orally with food, a single 50-mg dose of the oral suspension is reportedly bioequivalent to a single 50-mg conventional capsule. At a typical therapeutic regimen of 25-50 mg three times daily, steady-state plasma concentrations increase to 1.4 times that following the initial dose.

The extended-release capsules of indomethacin (designed to release 25 mg of the drug initially and the remaining 50 mg over an extended time period) are 90% absorbed within 12 hours.

The rate of absorption following rectal administration of suppositories of the drug generally has been reported to be more rapid than that following oral administration of conventional capsules. The manufacturer states that bioavailability following rectal administration of suppositories of the drug has been reported to be about 80-90% in controlled clinical studies; the decreased bioavailability compared with oral administration may have resulted from incomplete retention of the suppository (i.e., less than 1 hour) within the rectum.

Plasma concentrations of indomethacin fluctuate less and are more sustained following oral administration of a single 75-mg extended-release capsule than following oral administration of 3 doses of 25-mg conventional capsules at 4- to 6-hour intervals. In multiple-dose studies, the mean steady-state plasma concentration of indomethacin attained with daily administration of a 75-mg extended-release capsule was comparable to following administration of conventional indomethacin capsules in a dosage of 25 mg 3 times daily (given at 6-hour intervals); however, there were differences in the plasma indomethacin concentrations achieved with the 2 regimens, especially after 12 hours.

The disposition of indomethacin sodium following IV administration in premature neonates with patent ductus arteriosus (PDA) has not been extensively studied.

At therapeutic concentrations in adults, indomethacin is highly bound to plasma proteins (about 99%). Plasma protein binding has not been studied in neonates, although the incidence of bilirubin encephalopathy (kernicterus) was not increased, which indicates a lack of bilirubin displacement. Indomethacin crosses the blood-brain barrier and the placenta.

The drug is distributed into breast milk.

In premature neonates, the serum or plasma elimination half-life of indomethacin following IV injection is inversely related to postnatal age. In a limited number of neonates, the mean plasma half-life of indomethacin has been reported to be about 20 hours in those receiving the drug during the first week of life, compared to about 12 hours in those receiving the drug after the first week. The elimination half-life in neonates may also be inversely related to body weight.

In one study, the plasma indomethacin half-life showed considerable interindividual variation but averaged 21 hours in neonates weighing <1 kg and 15 hours in those weighing >1 kg.

Indomethacin is metabolized in the liver to its glucuronide conjugate and to desmethyl, desbenzoyl, and desmethyl-desbenzoyl metabolites and their glucuronides.

About 60% of an oral dose of indomethacin is excreted in urine (26% as indomethacin and its glucuronide) and 33% is excreted in feces (1.5% as indomethacin). Indomethacin undergoes appreciable enterohepatic circulation. The elimination half-life of indomethacin is approximately 4.5 hours.

Race does not affect the pharmacokinetics of indomethacin.

Indomethacin is used orally or rectally for anti-inflammatory and analgesic effects in the symptomatic treatment of moderate to severe rheumatoid arthritis (including acute flares of chronic disease), osteoarthritis, and ankylosing spondylitis. Indomethacin is also used orally or rectally for symptomatic treatment of acute painful shoulder (bursitis and/or tendinitis). Indomethacin immediate-release capsules, oral suspension, and rectal suppositories are used for the symptomatic treatment of acute gouty arthritis.

Generic name: indomethacin sodium

Reference product & biosimilars

No reference, biosimilar or interchangeable associated with this drug.

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Indications

The following indications are listed for Indomethacin:

  • Patent Ductus Arteriosus

Dosing

The lowest possible effective dosage and shortest duration of therapy consistent with treatment goals of the patient should be employed. Dosage of indomethacin must be carefully adjusted according to individual requirements and response, using the lowest possible effective dosage. Indomethacin 50-mg suppositories can be substituted for indomethacin capsules; however, there will be significant differences between the two dosage regimens in indomethacin blood levels.

Dosage of indomethacin sodium injection, is expressed in terms of anhydrous indomethacin; the IV injection is labeled for use only in premature infants with PDA.

Drug interactions

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Contraindications

*Indomethacin is contraindicated in patients with known hypersensitivity to the drug or any ingredient in the formulation.

*Nonsteroidal anti-inflammatory agents (NSAIAs), including indomethacin, generally are contraindicated in patients in whom asthma, urticaria, or other sensitivity reactions are precipitated by aspirin or other NSAIAs, since there is potential for cross-sensitivity between NSAIAs and aspirin, and severe, potentially fatal, anaphylactic reactions may occur in such patients.

*Indomethacin is contraindicated in the setting of coronary artery bypass graft (CABG) surgery.

*Indomethacin sodium for injection is contraindicated in neonates with congenital heart disease when patency of the ductus arteriosus is necessary for adequate pulmonary or systemic blood flow (e.g., neonates with pulmonary atresia, severe tetralogy of Fallot, or severe coarctation of the aorta).

*Indomethacin sodium for injection is contraindicated in neonates with proven or suspected, untreated infection.

*Indomethacin sodium for injection is contraindicated in neonates with active bleeding, such as those with intraventricular hemorrhage or GI bleeding, and in neonates with thrombocytopenia or underlying coagulation defect.

*Indomethacin sodium for injection is contraindicated in neonates with substantially impaired renal function.

*Indomethacin sodium for injection is contraindicated in neonates with known or suspected necrotizing enterocolitis.

*Indomethacin suppositories are contraindicated in patients with a history of proctitis or recent rectal bleeding.

Adverse reactions

Adverse effects reported in >=3% of patients receiving indomethacin in clinical trials include headache, dizziness, dyspepsia, and nausea.

The most common adverse effects reported in neonates receiving indomethacin sodium for injection for PDA include bleeding issues, a greater incidence of transient oliguria, and elevations in serum creatinine.

Precautions

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ICD codes

No ICD codes are available for this drug.

Formulary status

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Last reviewed · Source: First Databank (FDB) drug data