1. The difference between dexamethasone and betamethasone

2. Preterm delivery occurs in approximately 10% of all births and Preterm delivery occurs in approximately 10% of all births and results in approximately three fourths results in approximately three fourths of all neonatal deaths. of all neonatal deaths.

3. Complications : respiratory distress syndrome, respiratory distress syndrome, intraventricular hemorrhage intraventricular hemorrhage necrotizing enterocolitis necrotizing enterocolitis corticosteroid therapy has been used to reduce the frequency of neonatal complications, especially respiratory distress syndrome. corticosteroid therapy has been used to reduce the frequency of neonatal complications, especially respiratory distress syndrome.

4. enhancing fetal maturation enhancing fetal maturation given between 24 and 34 weeks' gestation. given between 24 and 34 weeks' gestation. dexamethasone and betamethasone

5. nongenomic effects cell metabolism cell metabolism cell membrane functions. cell membrane functions. metabolic pathways endothelial nitric oxide synthase endothelial nitric oxide synthase dexamethasone and betamethasone

6. a versus β orientation a versus β orientation of the methyl group at position 16. of the methyl group at position 16.

7. plasma half-life : 3–5 h plasma half-life : 3–5 h biologic half-life : 36–72 h biologic half-life : 36–72 h cross the placenta in biologically active forms cross the placenta in biologically active forms dexamethasone and betamethasone

8. placental enzyme 11β-hydroxysteroid dehydrogenase: converts cortisol to its inactive metabolic cortisone converts cortisol to its inactive metabolic cortisone

9. in the midgestation human, maternal cortisol level is consistently about 10 times higher than fetal plasma cortisol, suggesting that some maternal to fetal transfer of cortisol occurs. in the midgestation human, maternal cortisol level is consistently about 10 times higher than fetal plasma cortisol, suggesting that some maternal to fetal transfer of cortisol occurs.

10. Animal experiment MICE 1. lung maturity DEX is less potent than BETA in accelerating fetal lung maturity. DEX is less potent than BETA in accelerating fetal lung maturity.

11. Animal experiment MICE: 2. lung weight DEX markedly reduced the more than BETA. DEX markedly reduced the lung weight more than BETA. This reduced weight, evident in both sexes, was not reversible and persisted in the young adults This reduced weight, evident in both sexes, was not reversible and persisted in the young adults

12. Animal experiment MICE 3.The body weight DEX is less potent than BETA in accelerating fetal lung maturity. DEX is less potent than BETA in accelerating fetal lung maturity.

13. In 1994, the NIH recommended either : In 1994, the NIH recommended either : 1. two 12-mg doses of 1. betamethasone two 12-mg doses of given intramuscularly 24 hours apart given intramuscularly 24 hours apart 2. four 6-mg doses of given 2. dexamethasone four 6-mg doses of given intramuscularly 12 hours apart intramuscularly 12 hours apart between 24 and 34 weeks of gestation between 24 and 34 weeks of gestation

14. according to an NIH consensus : betamethasone is used more often to induce lung maturity betamethasone is used more often to induce lung maturity Although they both have the same biological activity and adverse effects, Although they both have the same biological activity and adverse effects,

15. Baud et al published a retrospective study of 883 infants with gestational ages between 24 and 31 weeks and found that betamethasone was associated with a lower risk of PVL (periventricular leukomalacia) than dexamethasone Baud et al published a retrospective study of 883 infants with gestational ages between 24 and 31 weeks and found that betamethasone was associated with a lower risk of PVL (periventricular leukomalacia) than dexamethasone Humen study

16. betamethasone maternal perception of fetal movements, fetal brething and body movements observed by ultrasound decreased significantly following the administration of betamethasone. maternal perception of fetal movements, fetal brething and body movements observed by ultrasound decreased significantly following the administration of betamethasone. Dexamethasone there was no significant change in fetal movements either as sensed by the mother or as observed by ultrasound there was no significant change in fetal movements either as sensed by the mother or as observed by ultrasound Humen study

17. Larger prospective clinical studies and larger sample sizes are needed to obtain more authoritative conclusions. Larger prospective clinical studies and larger sample sizes are needed to obtain more authoritative conclusions.