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Drug dosage identifier

Indomethacin

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Dose and administration

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1st dose: 200 micrograms/kg as IV infusion by syringe pump over 30 minutes.
Subsequent doses: 100 micrograms/kg/dose every 24 hours for a further 5 doses.

Indications

Closure of persistent patent ductus arteriosus.

Contraindications and precautions

  1. Anuria or oliguria (<0.5-1.0ml/kg/hour).
  2. Serum creatinine >150 micromol/L.
  3. Thrombocytopenia <80 x 109/L.
  4. Bleeding phenomena.
  5. Necrotising enterocolitis.

Clinical pharmacology

Indomethacin, an indole derivative, is one of the most potent inhibitors of the cyclo-oxygenase pathway. Inhibits the action of prostaglandin synthetase, and thus inhibits the synthesis of the prostaglandin E series. Indomethacin is a potent vasoconstrictor and decreases cerebral, gastrointestinal, and renal blood flow.

Very variable absorption from gastrointestinal tract (10-90%). Indomethacin solutions very susceptible to chemical decomposition. High binding (95%) to human plasma protein. No displacement of bilirubin from albumin at usual therapeutic levels. Hepatic metabolism, elimination via biliary tract and kidneys. Elimination half-life is approximately 30 hours (range 15-50 hours). Individual differences in rate of distribution, drug metabolism, rate of renal and biliary excretion, and re-entry of drug into the circulation by enterohepatic recirculation all contribute to the variability in plasma clearance.

Possible adverse effects

  1. Renal impairment
  2. Gastrointestinal dysfunction (abdominal distension, gastrointestinal bleeding, necrotising enterocolitis, gastric perforation, gastric ulceration).
  3. Platelet dysfunction and bleeding tendency.

Special considerations

  • Rapid infusions of intravenous indomethacin have been associated with significant reductions in cerebral blood flow.
  • Careful monitoring of gastrointestinal and renal status is required during a course of therapy.

Management of Indomethacin administration

Description

Pale yellow powder for reconstitution 1 mg/vial. Reconstituted solution is clear. For IV use only.

Prescription

Is charted on prescription chart in micrograms/dose.

Administration

Slow IV Infusion

  1. Reconstitution (no powder displacement). 
    Reconstitute with 2 ml water or 0.9% NaCl to make 1000 micrograms/2ml (=500 micrograms/ml).
    This will allow extra volume for ease of administration.
  2. Do NOT further dilute as indomethacin becomes very unstable.
  3. Draw up into 1ml syringe.
  4. Administer by slow IV infusion over 30 minutes using a syringe pump. Filter prior to administration through a 5 micron filter.
  5. Is compatible with 0.9% NaCl and water only.
  6. Do NOT mix with other drugs, IV solutions, blood or blood products.
  7. Ensure the dead space in the IV tubing is considered when administering the very small volumes of indomethacin.
  8. Flush with 0.9% NaCl before and after administration of indomethacin.

Observation and documentation

  1. Assess for signs of adverse effects.
  2. Maintain strict fluid balance. Report urinary output of<1-2 ml/kg/hour to doctor / NS-ANP.
  3. Perform urinalysis 8 hourly for blood, specific gravity and protein.
  4. Observe for evidence of bleeding.
  5. Assess for signs and symptoms of PDA. Auscultate for PDA closure.
  6. Monitor blood pressure at least 4 hourly.

Storage

  • At room temperature <30° C until reconstitution.
  • Protect from light.
  • Reconstituted solution not suitable for storage.

References

  1. Douidar SM, Richardson J, Snodgrass WR. Role of indomethacin in ductus closure: An update evaluation. Dev Pharmacol Ther 1988; 11:196-212. 
  2. Hammerman C, Aramburo MJ. Prolonged indomethacin therapy for the prevention of recurrences of patent ductus arteriosus. J Pediatr 1990; 117:771-6. 
  3. Shar N, Lindstrom DP, Cotton RB. Effect of slow infusion of indomethacin on cerebral blood flow in premature infants. Pediatr Res 1990; 27:225A.

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Document Control

  • Date last published: 27 September 2007
  • Document type: Drug Dosage Guideline
  • Services responsible: ADHB Pharmacy, Neonatology
  • Editor: Sarah Bellhouse
  • Review frequency: 2 years