Heme oxygenase activity is decreased by D-penicillamine in neonates

Oral D-penicillamine for the prevention of retinopathy of prematurity in very low birth weight infants: a randomized, placebo-controlled trial

PURPOSE

To compare prophylactic enteral D-penicillamine (DPA) with placebo for prevention of 'retinopathy of prematurity (ROP) or death' among very low birth weight (VLBW) infants.

METHODS

This was a double-blind, single-centre, randomized, placebo-controlled trial with stratification (for birth weight <1250 and ≥1250 g) and blocking. Inborn neonates with birth weight 750-1500 g, gestation ≤32 weeks, age ≤5 days, who tolerated feeds were eligible. Neonates with gastro-intestinal malformations, life-threatening malformations and necrotizing enterocolitis were excluded. Enrolled subjects were randomly allocated to receive oral DPA suspension at 100 mg/kg/dose 8 h for 3 days, followed by 50 mg/kg/day for another 11 days or placebo. The primary outcome was 'any ROP or death'. Secondary outcomes included any ROP, treatable ROP, adverse effects and feed intolerance.

RESULTS

A total of 88 subjects were enrolled. Baseline characteristics were similar with the exception of multiple gestation. There were no significant differences in primary and secondary outcomes, even after adjusting for multiple gestation and on sub-group analysis. No adverse reaction was noted.

CONCLUSION

Prophylactic enterally administered DPA suspension in a dose 100 mg/kg/dose 8 h for 3 days, followed by 50 mg/kg once per day for next 11 days, does not prevent 'any stage ROP or death' or 'ROP requiring treatment' in VLBW infants. DPA is well tolerated and does not have any major short-term adverse effects.

Recent advances in the pharmacotherapy for hyperbilirubinaemia in the neonate

Jaundice is a common cause for diagnostic works-up and therapeutic intervention in neonates. This is motivated by the risk for severe neurological sequelae (kernicterus). The mainstays of treatment for the past decades have been exchange transfusion and phototherapy. Exchange transfusion is now becoming rare due to immune prophylaxis in Rhesus-negative women, and treatment of sensitised infants with intravenous immunoglobulin. Several different pharmacological approaches have been studied as far as the treatment of neonatal jaundice. Of these, the focus of attention in recent years has been on the haem oxygenase inhibitors (metal meso- and protoporphyrins). These are effective inhibitors of bilirubin production and have been shown to significantly reduce peak serum bilirubin levels in several clinical trials, both when used prophylactically and therapeutically. However, questions remain regarding long-term safety, as well as the advisability of whole-scale inhibition of bilirubin production. Nevertheless, in selected infants with a high risk of severe jaundice, the use of haem oxygenase inhibitors may be acceptable. Pharmacotherapy in jaundiced infants is fraught with risks, as many drugs may increase the entry of bilirubin into the brain and presumably, the risk for neurotoxicity. Both the displacement of bilirubin from its albumin binding and interference with the function of phosphoglycoprotein in the blood-brain barrier are documented mechanisms in this respect.

Pharmacological interventions for the treatment of neonatal jaundice

In the neonate, hyperbilirubinaemia is usually due to a combination of an increased bilirubin load and decreased bilirubin elimination. Despite an understanding of the enzymatic pathways leading to bilirubin production and elimination, very few pharmacological interventions to prevent hyperbilirubinaemia are utilized and the mainstay of treatment remains phototherapy. Previously studied pharmacological agents such as D-penicillamine, phenobarbital and clofibrate may yet prove useful. Recent clinical trials using metalloporphyrins to inhibit heme catabolism and bilirubin production provides a novel pharmacological intervention for the treatment of neonatal jaundice. The safety and efficacy of these therapies will need to be confirmed prior to widespread use.

Elastin metabolism during perinatal lung development in the copper-deficient rat

Metal-chelating drugs were employed to investigate the role of copper (Cu) in elastin metabolism during the period of alveolarization in rat lung. Six groups of pregnant Sprague-Dawley rats were fed one of six semipurified diets, i.e., sufficient or deficient in copper, or the same basal diet containing 0.2% or 0.4% D-penicillamine (DPA), or the same basal diet containing 0.2% or 0.4% triethylenetetramine (TETA). The dams were fed throughout gestation, parturition, and lactation. The pups were then killed postnatally at day 10 and day 21 for the various analyses. At day 21, liver copper in the Cu-deficient pups was 3-5% control levels. In drug-treated groups, liver copper was 16-30% control levels. In the 21-day-old Cu-deficient rats, the concentration of lung elastin was only 75% of its concentration in control. Lung lysyl oxidase activity was lower in Cu-deficient rats, and data for the relative distribution of lung elastin cross-linking amino acids indicated impaired cross-linking in the pups from both the Cu-deficient and the 0.4% DPA groups. Morphologic examination of the lung also indicated dilation of airways in these two groups. Data on the distribution of cross-linking amino acids in elastin samples were also consistent with previous suggestions that impaired cross-linking observed in copper deficiency or from DPA treatment results from different mechanisms. Since the intakes of DPA and TETA were chosen to be in the therapeutic range of intakes used to treat diseases of abnormal copper metabolism, an important feature of these studies is that DPA and perhaps TETA have the potential of impairing normal lung development.