A short course of early dexamethasone therapy with a starting dose of 0.5 mg/kg/day improves lung compliance and shortens the duration of ventilatory support in preterm infants with respiratory distress syndrome (RDS)(Pediatrics 1995;95:584-590). We conducted a double-blind, randomized study to evaluate whether an early 14-day weaning course of low dose dexamethasone improves lung function and reduces the side effects of dexamethasone. Eighteen preterm infants who required ventilatory support for RDS were randomized to and completed a 14-day treatment course with dexamethasone (0.2 mg/kg/day start, tapering doses) or placebo (equivalent amounts of normal saline). The infants were 6.1 ± 3.8 (mean ± SD, range 0-15) days old at study entry, their gestational age was 29.3 ± 1.8 (26-32) weeks and their birth weight 1,126 ± 334 (657-1,767) g. Prior to the first study treatment, adrenal function was assessed from cortisol levels drawn before and 30 min after intravenous administration of 0.1 mg Cortrosyn. The ACTH stimulation test was repeated the day after completion of the 14-day treatment course. Cortisol levels were measured using a radioimmunoassay. At the start of the study, basal cortisol levels of the 18 infants were 4.1 ± 2.9(<1 - 8.8) μg/dl, stimulated cortisol levels were 12.9 ± 7.1 (1.1- 28.4) μg/dl, and cortisol levels >15 μg/dl were found in 0/18 infants before and in 9/18 infants after ACTH stimulation. In the placebo group (n=10), basal (4.2 ± 3.1 and 1.6 ± 1.0 μg/dl) and stimulated cortisol levels (13.8 ± 7.0 and 14.6 ± 5.2 μg/dl) did not change during treatment, but the number of infants with stimulated cortisol levels >15 μg/dl increased from 4 to 7. In the dexamethasone group (n=8), basal (3.9 ± 2.7 and 2.9 ± 2.2 μg/dl) and stimulated cortisol levels (11.7 ± 7.6 and 14.1 ± 5.8 μg/dl) did not change either, but only 2 infants had stimulated cortisol levels>15 μg/dl before and after dexamethasone therapy. Prenatal steroids had been administered to 4/10 infants in the placebo group and to 8/8 infants in the dexamethasone group. These data suggest that an early 14-day weaning course of low dose dexamethasone has little impact on the adrenal function of very preterm infants with RDS.
