Eur J Pediatr (2011) 170:1495–1505 Table 1 Basic characteristics of commonly used natural and synthetic corticosteroids [36] Agent Activity Short- to medium-acting GCs Hydrocortisone (cortisol) Cortisone Prednisone Prednisolone Methylprednisolone Meprednisone Intermediate-acting GCs Triamcinolone 5 Paramethasone 10 Fluprednisolone 15 Long-acting GCs Betamethasone 25–40 Dexamethasone 30 Mineralocorticoids Fludrocortisone 10 Desoxycorticosterone acetate 0 1 0.8 4 5 5 5 Anti-inflammatory Topical Salt-retaining Equivalent oral Forms dose (mg) available 1 0 0 4 5 5 – 7 10 10 0 0 – 0 0 0 0 0 250 20 1 0.8 0.3 0.3 0 0 20 25 5 5 4 4 2 – 4 2 1.5 0.6 0.75 1499 p.o., inj., top. p.o. p.o., inj. p.o., inj. p.o., inj. p.o., inj. p.o., inj., top. p.o., inj. p.o. p.o., inj., top. p.o., inj., top. p.o. p.o., inj. Due to the relatively wide spectrum and high risk of side effects of systemic GCs, the local administration of GCs is generally preferred. However, depending on the system of delivery and dose used, <20% of the nebulized GCs is deposited into the lungs and the rest may be absorbed into the circulation from the gastrointestinal system and subse- quently cause systemic effects [61]. In addition, inhalation of GCs may worsen the course of bacterial infections after initial improvement and may increase the risk of oropha- ryngeal candidiasis, dysphonia, cough, throat irritation and other local side effects [3]. Use of GCs in perinatal respiratory diseases In respirology, GCs (mainly inhalational GCs such as budesonide) are used in asthma and exacerbations of chronic obstructive pulmonary disease [6, 43, 61]. In perinatal period, GCs may be administered antenatally or postnatally. Antenatal GCs (particularly betamethasone and dexamethasone) are used to induce early lung maturation and stimulate the synthesis of pulmonary surfactant in premature infants [5, 60]. Postnatally, GCs (especially dexamethasone) take part in the treatment of chronic lung disease or bronchopulmonary dysplasia after neonatal respiratory distress syndrome [1, 40, 83]. However, long- term GCs administration may exert adverse effects on neuromotor function and the somatic growth of the treated infants [89]. In adult/acute respiratory distress syndrome, GCs (mostly methylprednisolone) may be of benefit in fibroproliferative or late phase of the disease, but use in the early stages of the disease is controversial [24, 34]. Use of GCs in MAS In animal models and in newborns with MAS, hydrocor- tisone, prednisolone, methylprednisolone, dexamethasone and budesonide have been used, with the subjects having various responses to treatment. Hydrocortisone is a synthetic equivalent of cortisol and used as an immunosuppressive drug in severe allergic reactions such as anaphylaxis and angioedema. Comparing the strength for the anti-inflammatory effect, prednisolone is about four times and dexamethasone is about 30 times stronger than hydrocortisone. Thanks to both glucocorticoid and mineralocorticoid effects, hydrocortisone may be used in substitution therapy; however, expressing mineralocorti- coid activity, hydrocortisone may potentiate a dysbalance of liquids and electrolytes in the body. In the study by Frantz et al. [25] carried out in 1975, the subcutaneous administration of hydrocortisone at a dose of 7.5 mg/kg immediately after meconium instillation and then every 8 h up to 48 h non-significantly improved the histology of the lungs and decreased the frequency of breathing in newborn rabbits. However, a higher mortality of the hydrocortisone-treated animals was observed irre- spective if they aspired meconium or saline, probably due to the infection at the tracheotomy site and sepsis [25]. Two years later, hydrocortisone, at a dose of 20 mg/kg, was