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Neonatal Intensive Care Drug Manual
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| bet | 518/654 | | Sana | 03.01.2022 | | Hajmi | 1,5 Mb. | | #14803 |
Phaeochromocytoma: This is rare in infants. Case series describe successful pre-operative management of hypertension with a sequential combination of phenoxybenzamine (alpha-blocker) (0.2 to 4 mg/kg/day) and propranolol (1 to 10 mg/kg/day).[21, 22]
Neonatal thyrotoxicosis: Beta-blockers (propranolol 2 mg/kg/day divided in 2 doses for 1–2 weeks) are effective at controlling the symptoms such as tachycardia, hypertension, and poor feeding.33 Other suggested regimens included 8-hourly doses.34-37
Pharmacokinetics/pharmacodynamics:
Propranolol is highly lipophilic and undergoes first-pass metabolism by the liver with only ∼25% of oral propranolol reaching the systemic circulation. Multiple pathways in the cytochrome P450 system are involved in propranolol’s metabolism.[23]
Filippi et al 2013 [24] reported pharmacokinetic parameters at steady state in newborns treated with 0.5 mg/kg 6 hourly. The maximal (71.7 ± 29.8 ng/mL), minimal (42.2 ± 20.8 ng/mL) and average concentration (60.8 ± 25.0 ng/mL), time of maximal concentration
(2.6 ± 0.9 hour) and area under the time-concentration curve (364.7 ± 150.2 ng/mL/hour) were similar to those observed in adults. In both dosing groups, elimination half-life was significantly longer (14.9 ± 4.3 and 15.9 ± 6.1 hours) and apparent total body clearance (27.2 ± 13.9 and 31.3 ± 13.3 mL/kg/min), lower than reported in adults, suggesting a slower metabolism in newborns. No differences were observed between newborns with different gestational age or different sex.
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