Indomethacin therapy in premature infants of advanced postnatal age.

Indomethacin (0.3 mg/kg every eight hours IV for three doses) was administered to eight infants whose postnatal ages were eight weeks or greater and who developed patent ductus arteriosus either in the late postnatal life or in the early neonatal period but persisted. In spite of maintenance of appropriate plasma indomethacin levels, none of the infants responded with ductus closure. The present study suggests that a distinct group of infants may exist whose ductus arteriosus is prostaglandin independent and the patency of the ductus may persist.