The treatment of patent ductus arteriosus in preterm infants. A review and overview of randomized trials

Reported adverse drug events in infants and children under 2 years of age

OBJECTIVE

To characterize risks to infants and young children from drugs and biological products that were identified in spontaneous adverse event reports submitted to the US Food and Drug Administration.

METHODS

Of >500 000 MedWatch adverse event reports received by the Food and Drug Administration from November 1997 through December 2000, we identified 7111 reports about infants and children younger than age 2. The reports were analyzed for health outcome (eg, death, hospitalization, congenital anomaly), principal suspect drug, and whether the route of drug exposure was direct administration or through the mother in the perinatal period.

RESULTS

Drug therapy was associated with an average of 243 reported deaths annually over the 38-month study period, with 100 (41%) occurring during the first month of life and 204 (84%) during the first year. In 1432 (24%) reported adverse event cases of all levels of severity, exposure to the drug was from the mother during pregnancy, delivery, or lactation. Although 1902 different drugs, biological products, and other chemicals were identified in the reports, only 17 drugs or biological products were a suspect in 54% of all serious and fatal adverse events in drugs administered directly.

CONCLUSION

Adverse reactions to drug therapy are a significant cause of death and injury in infants and children under 2 years of age. Drugs administered to the mother in the perinatal period constituted a major route of exposure to adverse drug advents. These results underscore the need for additional drug testing in the youngest pediatric patients and for carefully weighing the risks versus benefits of medication.

COX-1 and COX-2 contributions to basal and IL-1 beta-stimulated prostanoid synthesis in human neonatal cerebral microvascular endothelial cells

Mechanisms of endothelium-dependent regulation of cerebral circulation in human neonates are poorly understood owing to the lack of experimental data. Prostanoids, the products of the cyclooxygenase (COX) pathway, appear to be important regulators of blood flow in neonates. COX activity in cultured endothelial cells from small (60-300 microm) and large (>300 microm) microvessels from the autopsy specimens of neonatal human cerebral cortex and cerebellum (22-26 wk gestational age) was detected as production of vasodilator prostanoids, prostacyclin [as 6-keto-prostaglandin (PG) F(1 alpha)] and PGE(2) from arachidonic acid. Treatment of neonatal human cerebral microvascular endothelial cells (hCMVEC) with IL-1 beta (50 ng/mL, 17 h) stimulated COX activity 5- to 20-fold. Basal and IL-1 beta-stimulated COX activities were inhibited by NS-398, indicating substantial COX-2 contribution to endothelial prostanoid synthesis in neonatal human brain cortex and cerebellum at rest and when mimicking the inflammatory conditions. Increased COX-2-linked activity in response to IL-1 beta was observed in hCMVEC from both cerebrum and cerebellum (5- to 20-fold), while under the same conditions elevated COX-1-linked activity was detected only in hCMVEC from cerebellum (5- to 10-fold). In IL-1 beta-treated hCMVEC, a shift toward PGE(2) as the major vasodilator product of the COX pathway was observed. Acute treatment with the protein tyrosine kinase inhibitor, tyrphostin 25, inhibited basal and IL-1 beta-induced COX activities, suggesting the importance of posttranslational modifications in endothelial COX-2 activation in human brain. Altogether, these data indicate that both COX-1 and COX-2 contribute to endothelial prostanoid synthesis in the neonatal human brain under basal conditions and in response to proinflammatory cytokine IL-1 beta.

Pulmonary hypertension after ibuprofen prophylaxis in very preterm infants

We report three cases of severe hypoxaemia after ibuprofen administration during a randomised controlled trial of prophylactic treatment of patent ductus arteriosus with ibuprofen in premature infants born at less than 28 weeks of gestation. Echocardiography showed severely decreased pulmonary blood flow. Hypoxaemia resolved quickly on inhaled nitric oxide therapy. We suggest that investigators involved in similar trials pay close attention to pulmonary pressure if hypoxaemia occurs after prophylactic administration of ibuprofen.

Retinopathy of prematurity: causation

The incidence of ROP is birth weight dependent and restricting therapeutic oxygen levels has dramatically reduced the incidence of ROP in infants of birth weight >1000 g. However, the incidence of ROP has remained high in very low birth weight (VLBW) infants and this appears to be related to these babies being more ill. Several risk factors have been identified in this group, however oxygen variability, rather than high levels, has been correlated with severity of disease in recent clinical and animal studies. Difficulties in defining 'normal' oxygen in this group has meant the optimal range of oxygen therapy has not yet been defined. Clinical studies are now underway using even lower oxygen therapy ranges. The impact this may have on ROP, neurological and respiratory outcomes will require further study.

Intravenous indomethacin for preventing mortality and morbidity in very low birth weight infants

BACKGROUND

This section is under preparation and will be included in the next issue.

OBJECTIVES

Indomethacin is used to treat symptomatic patent ductus arteriosus and may prevent or limit intraventricular haemorrhage in the neonatal period. This review examines the effectiveness of prophylactic intravenous indomethacin in reducing the mortality and morbidity associated with these conditions in infants weighing less than 1750 grams at birth.

SEARCH STRATEGY

A literature search from January 1980 to October 1994 was made in three computerised data bases: Medline; Embase; and the Oxford Database of Perinatal Trials. The search was updated in February 1997.

SELECTION CRITERIA

Strict selection criteria were applied to clinical trials: the population had to be newborn infants of birth weight < 1751 grams; the intervention had to be prophylactic intravenous indomethacin; the trial had to be randomised and controlled; and at least one of several prespecified outcomes had to be reported in the results.

DATA COLLECTION AND ANALYSIS

The methodological quality of each study was assessed using explicit criteria. Data on relevant outcome measures were extracted on two separate occasions and, where appropriate, the results of individual trials were combined using meta-analysis techniques to provide a pooled estimate of effect.

MAIN RESULTS

There is a trend towards reduced neonatal mortality in infants receiving prophylactic indomethacin, pooled relative risk (RR) = 0. 85 [95% CI 0.66 to 1.09]. The incidence of symptomatic patent ductus arteriosus is significantly reduced in treated infants, pooled RR = 0.35 [0.26 to 0.47] but there is no evidence that treatment affects respiratory outcomes. Prophylactic indomethacin significantly reduces the incidence of Grade 3 and 4 intraventricular haemorrhage in treated infants, pooled RR = 0.60 [0.43 to 0.83]. There is no evidence to suggest prophylactic indomethacin is associated with any long term adverse effect although there is a trend in treated infants towards an increased incidence of necrotizing enterocolitis, and some evidence that treatment may transiently impair renal function. There is no evidence that haemostasis is disturbed.

REVIEWER'S CONCLUSIONS

Prophylactic treatment with indomethacin has a number of immediate benefits, in particular a reduction in symptomatic patent ductus arteriosus and severe intraventricular haemorrhage. There is no evidence at present of long-term harm. Further trials are needed to assess more precisely the effects, both beneficial and harmful, on short and long-term outcomes.