Recovery of prostaglandin production associated with reopening of the ductus arteriosus after indomethacin treatment in preterm infants with respiratory distress syndrome.

Increased PGE production has been demonstrated in 9 of 17 preterm infants with patent ductus arteriosus (PDA) associated with respiratory distress syndrome (RDS). Inhibition of PGE production in eight preterm infants with PDA and RDS was associated with marked improvement in the respiratory and circulatory function of all of them. However, in six of them this effect was only transient. In the posttreatment period of five and a half days reopening of the ductus arteriosus was frequently associated with increased PGE production and a drop of indomethacin serum levels. Three of these six infants were transferred for surgical ligation whereas the other three were successfully treated with a second course of indomethacin. However, the margin between closure of the ductus arteriosus and the deterioration of kidney function in preterm infants treated with a presently recommended indomethacin dosage was narrow. In conclusion, until an acceptable therapeutic serum level of indomethacin for ductal closure in preterm infants has been established and the duration of effective prostaglandin synthesis inhibition is known, it is too early for a general recommendation of a dosage regime of indomethacin for the pharmacological closure of PDA in infants with RDS.