Objective. Symptomatic patent ductus arteriosus (sPDA) is a common problem in premature infants and can be treated effectively with intravenous indomethacin, leading to permanent ductal closure in 70% to 80% of infants. Infants who do not respond to pharmacologic closure of the duct ultimately have to undergo surgical or interventional closure of the PDA. Optimizing the pharmacologic treatment could offer an interesting approach to reduce the number of infants who need surgical closure of the duct.

Methods. We conducted a retrospective analysis in infants who were <33 weeks’ gestation, had sPDA, and were treated with high-dose intravenous indomethacin. From 1993 to 2002, 129 infants with sPDA received indomethacin after diagnosis of sPDA was confirmed by echocardiography. Treatment was started in all infants with intravenous indomethacin (0.2 mg/kg given 5 times at 0 hours, 12 hours, 24 hours, 48 hours, and 72 hours). When the ductus was still open at 36 hours, indomethacin every 12 hours was continued and single doses increased up to 1 mg/kg until ductal closure was achieved.

Results. In 68 (53%) of 129 infants who were treated with indomethacin, ductal closure occurred during intermediate-dose indomethacin therapy (up to 1.5 mg/kg total dose). In the 61 initial nonresponders, the continuation of indomethacin led to ductal closure in 59 infants. When infants who were treated with an intermediate dose were compared with the initial nonresponders, no differences in the incidences of renal or electrolyte abnormalities, gastrointestinal bleeding, intraventricular hemorrhage, or periventricular leukomalacia were found.

Conclusions. High-dose indomethacin after intermediate-dose therapy resulted in an overall closure rate of 98.5% (127 of 129). Although single indomethacin doses of up to 1 mg/kg were given, high-dose indomethacin was safe.

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