Pharmacological Therapies for Unconjugated Hyperbilirubinemia

Crigler-Najjar syndrome: looking to the future does not make us forget the present

Recently, the safety and efficacy of gene therapy were evaluated in patients with Crigler-Najjar syndrome (CNS). Although it is a promising curative option for CNS, many doubts still persist about its long-term efficacy and safety. Furthermore, there is a risk of overlooking several unresolved problems still present in current clinical practice. This letter is a call for action on crucial open issues that remain nowadays an unmet need in the management of CNS patients.

Indirect Neonatal Hyperbilirubinemia and the Role of Fenofibrate as an Adjuvant to Phototherapy

BACKGROUND

One of the most prevalent illnesses in neonates that needs care and treatment is neonatal jaundice. Several drugs are used as pharmacological modalities for treating hyperbilirubinemia, like intravenous immunoglobulin, D-penicillamine, metalloporphyrin, phenobarbital, zinc sulfate and clofibrate. Previous studies suggest the usefulness of fenofibrate in the treatment of hyperbilirubinemia.

OBJECTIVES

The study aims at assessing the effectiveness of oral fenofibrate in the treatment of indirect neonatal hyperbilirubinemia in full-term neonates.

METHOD

This is a quasi-experimental study that was conducted at Heevi Pediatrics Teaching Hospital in Duhok, which is located in the Kurdistan Region of Iraq. It involved term infants who had jaundice. The neonates who were eligible for the study were randomly assigned to one of two groups: the intervention group or the control group. Both groups were treated with conventional phototherapy. Fenofibrate was administered in a single oral dose of 10 mg/kg to the participants in the intervention group. Throughout the entirety of the treatment, levels of total serum bilirubin were compared and contrasted between the two groups.

RESULTS

After 12 h of treatment, a statistically significant difference (p-value = 0.001) was seen in the serum bilirubin levels between the two groups. The difference in serum bilirubin levels became significantly progressively pronounced after 24, 48, and 72 h. The average time of discharge was 63.6 h for the intervention group and 90.9 h for the control group, and this difference was statistically significant (p-value < 0.001).

CONCLUSIONS

The time it takes to lower high bilirubin levels in neonates may be shortened by combining conventional phototherapy with a single oral dosage of 10 mg/kg fenofibrate. Consequently, these neonates will experience a shorter hospitalization and an accelerated discharge from the hospital.

Activation of Alternative Bilirubin Clearance Pathways Partially Reduces Hyperbilirubinemia in a Mouse Model Lacking Functional Ugt1a1 Activity

Bilirubin is a heme catabolite and Ugt1a1 is the only enzyme involved in the biological elimination of bilirubin. Partially functional or non-functional Ugt1a1 may result in neuronal damage and death due to the accumulation of unconjugated bilirubin in the brain. The understanding of the role of alternative bilirubin detoxification mechanisms that can reduce bilirubin toxicity risk is crucial for developing novel therapeutic strategies. To provide a proof-of-principle showing whether activation of alternative detoxification pathways could lead to life-compatible bilirubin levels in the absence of Ugt1a1 activity, we used Ugt1^−/− hyperbilirubinemic mice devoid of bilirubin glucuronidation activity. We treated adult Ugt1^−/− mice with TCPOBOP, a strong agonist of the constitutive androstane receptor (CAR). TCPOBOP treatment decreased plasma and liver tissue bilirubin levels by about 38%, and resulted in the transcriptional activation of a vast array of genes involved in bilirubin transport and metabolism. However, brain bilirubin level was unaltered. We observed ~40% degradation of bilirubin in the liver microsomes from TCPOBOP treated Ugt1^−/− mice. Our findings suggest that, in the absence of Ugt1a1, the activation of alternative bilirubin clearance pathways can partially improve hyperbilirubinemic conditions. This therapeutic approach may only be considered in a combinatorial manner along with other treatments.

The effects of clofibrate on neonatal jaundice: A systematic review

Background:

Neonatal jaundice is a prevalent disease that causes many complications, including kernicterus and even death. Previous studies have shown that clofibrate as an aryloxy isobutyric acid derivate can be effectively applied for the treatment of neonatal jaundice. Thus, this review was carried out to investigate the effects and mechanism of action of clofibrate on neonatal jaundice.

Methods:

The keywords such as “Clofibrate” in combination with “Neonatal jaundice” or “Neonatal hyperbilirubinemia” or “Newborn Jaundice” were used to search for relevant publications indexed in the Institute for Scientific Information (ISI), Scopus, PubMed, and Google Scholar databases. Finally, after reviewing the studies, 24 papers were included in this study.

Results:

Results showed that the processes of albumin-bound bilirubin transfer to the hepatocytes, hepatic uptake, and storage via ligandin, hepatic conjugation via uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1), conjugation into the bile via MRP2 represent the main action mechanism of clofibrate that turns it into the bilirubin conjugates and expels it from the bile. Besides, clofibrate has been shown to reduce the level of Total Serum Bilirubin (TSB) in infants even at a dosage of 25 mg/kg without leaving side effects.

Conclusions:

The results of this review revealed that clofibrate effectively reduces TSB in short-term usage and can even have a promising effect at the dosage of 25 mg/kg in full-term infants. Most studies have shown this property over a short period in term infants, and there is no evidence about long-term usage in this regard.

An Epileptic Patient with Recurrent Hyperbilirubinemia Caused by Gilbert Syndrome

Gilbert syndrome (GS) is characterized by intermittent indirect bilirubin elevation. Several antiepileptic drugs (AEDs) impair the liver function to different degrees, such as valproic acid, lamotrigine, phenobarbital, phenytoin, and carbamazepine. Herein, we present the case of a 26-year-old epileptic patient with frequently recurring mild hyperbilirubinemia during taking AEDs. After repeated adjustment of the doses and types of AEDs, the bilirubin level still remained elevated. He was then referred to the Gastroenterology Department. The results of diagnostic tests, clinical manifestation, imaging studies, liver biopsy and whole-exome sequencing all made contributions to our conclusion that GS played an important role in the elevation of bilirubin. Ultimately, his seizure was controlled by levetiracetam (500 mg per day) and he was advised to periodically undergo the liver function tests.

[Effects of Yinzhihuang oral liquid and Lonicera japonica extract on hemolysis and hyperbilirubinemia in rats with glucose-6-phosphate dehydrogenase deficiency]

OBJECTIVE

To investigate the effects of different doses of Yinzhihuang oral liquid and different concentrations of Lonicera japonica extract on hemolysis and hyperbilirubinemia in rats with glucose-6-phosphate dehydrogenase (G6PD) deficiency.

METHODS

Male Wistar rats were randomly divided into 10 groups (n=10 each): normal control group (untreated), negative control group (saline-treated), positive control group (primaquine-treated), low-, medium- and high-dose Yinzhihuang oral liquid groups (13.4, 26.8, and 53.6 mL/kg, respectively), and low-, medium-, high-, and very-high-concentration Lonicera japonica groups (6.7 mL/kg administered, containing 8, 40, 80, and 160 mg/mL Lonicera japonica extract, respectively). A rat model of acetylphenylhydrazine-induced G6PD deficiency was established in all groups except the normal control group, as confirmed by the morphological changes in erythrocytes observed using Wright's stain. After treatment, routine blood and biochemical tests were conducted to measure hemolytic indices, as well as changes in total and indirect bilirubin levels.

RESULTS

Rats with G6PD deficiency demonstrated irregular erythrocytes with a lighter-staining center. In the positive control group, the red blood cell count decreased, while the free hemoglobin count and the reticulocyte percentage increased, as compared with before treatment (P<0.05); in all the Yinzhihuang oral liquid groups and Lonicera japonica extract groups, all the above indices except reticulocyte percentage returned to the levels before treatment (P<0.05). Compared with the positive control group, all the Yinzhihuang oral liquid groups had significantly reduced total and indirect bilirubin levels (P<0.05), and all the Lonicera japonica group had significantly reduced indirect bilirubin levels (P<0.05). However, the total bilirubin level was significantly higher in the Lonicera japonica groups than in the Yinzhihuang oral liquid groups (P<0.05). The low-dose Yinzhihuang oral liquid group demonstrated a significantly greater decrease in total bilirubin level than the medium- and high-dose Yinzhihuang oral liquid group (P<0.05).

CONCLUSIONS

Administration of high-dose Yinzhihuang oral liquid and different concentrations of Lonicera Japonica extract do not cause hemolysis in rats with G6PD deficiency. Yinzhihuang oral liquid is more effective in treating hyperbilirubinemia than Lonicera Japonica extract. However, the efficacy of Yinzhihuang oral liquid may not be dose-dependent.

[Management of jaundice in the newborn≥35 GW: From screening to follow-up after discharge. Guidelines for clinical practice]

Jaundice due to unconjugated bilirubin is an everyday condition in the neonatal period because it results from the adaptation of bilirubin metabolism at this time of life. Hyperbilirubinemia has a potential neurotoxicity and although it most often resolves spontaneously, it can lead to acute and sometimes chronic encephalopathy. The latter condition is called kernicterus and induces severe and irreversible neurological sequelae. This rare complication is still reported in all countries throughout the world even if severe hyperbilirubinemia can be prevented and critical points points of failure in jaundice management are identified. Jaundice management are identified, jaundice is the most frequent symptom during the first days of life and after discharge from the maternity ward but also the major cause of readmission in the 15 first days of life. Therefore in the past 20 years, numerous countries have written national practical guidelines for the management of neonatal jaundice using various methodologies. Most of the time, the guidelines resulted from expert consensus more than from an evidence-based argument. The Société française de néonatologie created a working group to provide the first French clinical guidelines for the management of jaundice in the near-term newborn (35 weeks and more). They were written following a physiopathological argument and taking into account both clinical risk factors for severe hyperbilirubinemia and interindividual variability in vulnerability to bilirubin neurotoxicity. Practical tools were also developed to facilitate implementation of the guidelines and are also included.

Thymoquinone, an active constituent of Nigella sativa seeds, binds with bilirubin and protects mice from hyperbilirubinemia and cyclophosphamide-induced hepatotoxicity

Some reports indicate that thymoquinone (TQ), the main constituent of Nigella sativa seeds, is hepatoprotective. The aim of this study was to determine whether TQ is able to bind directly to bilirubin, and whether TQ or liposomal formulation of TQ (Lip-TQ) can reduce cyclophosphamide (CYP)-induced liver toxicity, serum bilirubin level in mice. The binding of TQ with bilirubin was studied by UV-VIS, fluorescence and Near-UV CD spectroscopy. Inhibition of binding of bilirubin to erythrocytes by TQ was also examined. To increase the in vivo efficacy, Lip-TQ was prepared and used against CYP-induced toxicity. The protective role of TQ or Lip-TQ against CYP-induced toxicity was assessed by determining the liver function parameters, the levels of superoxide dismutase (SOD) and catalase (CAT), and histological studies. It was found that TQ binds to bilirubin and significantly inhibits the binding of bilirubin to erythrocytes. Lip-TQ (10 mg/kg) significantly reduced the levels of aspartate transaminase (AST) from 254 ± 48 to 66 ± 18 IU/L (P < 0.001), alanine transaminase (ALT) from 142 ± 28 to 47.8 ± 16 IU/L (P < 0.05) and serum bilirubin from 2.8 ± 0.50 to 1.24 ± 0.30 mg/dl (P < 0.05). Treatment with Lip-TQ reduced the CYP-induced inflammation and hemorrhage in liver tissues. Moreover, treatment with free or Lip-TQ protected the activity of SOD and CAT in CYP-injected mice. Therefore, TQ can reduce the level of bilirubin in systemic circulation in disease conditions that lead to hyperbilirubinemia and liver toxicity and hence may be used as a supplement in the treatment of liver ailments.

UGT1A1 genetic analysis as a diagnostic aid for individuals with unconjugated hyperbilirubinemia

OBJECTIVE

To assess the clinical utility of UGT1A1 genetic testing and describe the spectrum and prevalence of UGT1A1 variations identified in pediatric unconjugated hyperbilirubinemia (UCH), and to characterize specific genotype-phenotype relationships in suspected Gilbert and Crigler-Najjar syndromes.

STUDY DESIGN

A retrospective study was conducted to review clinical information and UGT1A1 genotyping data from 181 pediatric patients referred for UCH. In silico analyses were performed to aid in the assessment of novel UGT1A1 variants.

RESULTS

Overall, 146/181 pediatric patients had at least one heterozygous UGT1A1 functional variant. Identified UGT1A1 variants included 17 novel variants, 7 rare star alleles, and 1 rare variant. There were 129 individuals who possessed the TA7 (*28) promoter repeat and 15 individuals who possessed the *6 (c.211G > A) variation. Out of the 104 individuals with accompanying bilirubin levels, 41 individuals did not have identifiable UGT1A1 variants that explained their UCH, although glucose-6-phosphate dehydrogenase deficiency and other causes of UCH could not be ruled out.

CONCLUSION

Much of the observed UCH could be attributed to variation at the UGT1A1 locus, and UGT1A1 testing helped to substantiate a genetic diagnosis, thereby aiding in individual and family disease management. Although UGT1A1 variation plays a large role in UCH, genetic assessment of UGT1A1 alone may not be comprehensive. Assessment of additional genes may also be useful to evaluate genetic causes for UCH.

Dexamethasone reduces bilirubin-induced toxicity and IL-8 and MCP-1 release in human NT2-N neurons

The mechanisms of neurotoxicity induced by unconjugated bilirubin (UCB) in newborns are incompletely understood. UCB may cause both necrotic and apoptotic neuronal death. We explored UCB toxicity and release of cytokines in human NT2-N neurons and the effect of dexamethasone on these processes. Cultured NT2-N neurons were exposed to UCB, and neuronal damage was evaluated by LDH release and MTT cleavage. After 96 hours, 2 μM UCB significantly increased release of IL-8 and MCP-1, but not IL-13, IP-10, PDGF, or VEGF. Dexamethasone significantly lowered the UCB-induced increase in MCP-1 release, and attenuated UCB-induced neuronal damage assessed with MTT cleavage and LDH release. For comparison, the effects of hydrogen peroxide on cytokine formation and neuronal damage were tested. Hydrogen peroxide increased MCP-1, IP-10, and VEGF, but not IL-8, IL-13, or PDGF. Dexamethasone inhibited the hydrogen peroxide-induced increase in MCP-1 and IP-10. We conclude that UCB causes release of IL-8 and MCP-1 in cultured human NT2-N neurons. Dexamethasone reduces UCB-induced cytokine release and protects against UCB-induced toxicity.

An evidence-based view on hyperbilirubinaemia

INTRODUCTION

We conducted a review of the evidence which contributes to the current care of jaundiced newborn infants.

METHODS

Literature was searched for reviews and randomized controlled trials (RCTs).

RESULTS

Six Cochrane reviews and eight other reviews and eighteen recent RCTs are discussed.

CONCLUSIONS

Many children still suffer life-long consequences of severe hyperbilirubinaemia, which could almost always have been prevented relatively easily. Up to date, guidelines summarizing the available evidence into unambiguous recommendations are needed to guide healthcare professionals in the prevention, diagnosis and treatment for infants with hyperbilirubinaemia.

Scoparone potentiates transactivation of the bile salt export pump gene and this effect is enhanced by cytochrome P450 metabolism but abolished by a PKC inhibitor

BACKGROUND AND PURPOSE

Hyperbilirubinaemia and cholestasis are two major forms of liver abnormality. The Chinese herb Yin Chin has been used for thousands of years to treat liver dysfunctions. In mice, this herb and its principal ingredient scoparone were found to accelerate the clearance of bilirubin accompanied by the induction of uridine diphosphate-5'-glucuronosyltransferase-1A1 (UGT1A1), a bilirubin processing enzyme. The aim of this study was to determine whether scoparone induces the expression of human UGT1A1. In addition, the expression of the bile salt export pump (BSEP), a transporter of bile acids, was determined.

EXPERIMENTAL APPROACH

Primary human hepatocytes and hepatoma line Huh7 were treated with scoparone, chenodeoxycholic acid (CDCA) or both. The expression of UGT1A1 and BSEP mRNA was determined. The activation of the human BSEP promoter reporter by scoparone was determined in Huh7 cells by transient transfection and in mice by bioluminescent imaging. The metabolism of scoparone was investigated by recombinant CYP enzymes and pooled human liver microsomes.

KEY RESULTS

Scoparone did not enhance the expression of either human BSEP or, surprisingly, UGT1A1. However, scoparone significantly potentiated the expression of BSEP induced by CDCA. Consistent with this, scoparone potentiated the stimulant effect of CDCA on the human BSEP promoter. This potentiation was enhanced by co-transfection of cytochrome P4501A2 but abolished by the PKC inhibitor GF109203X.

CONCLUSIONS AND IMPLICATIONS

Scoparone and Yin Chin normalize liver function primarily by enhancing the secretion of bile acids, and this effect probably varies depending on the metabolic rate of scoparone.

Clofibrate for unconjugated hyperbilirubinemia in neonates: a systematic review

OBJECTIVE

To evaluate the effect of clofibrate for unconjugated hyperbilirubinemia in neonates.

METHODS

A systematic review with meta-analysis of randomized controlled trials or quasi-randomized controlled trials was conducted to evaluate the clofibrate treatment in neonates with unconjugated hyperbilirubinemia. We followed the guidelines from the Cochrane review group and the PRISMA statement.

RESULTS

Of 148 studies identified, a total of 13 studies on 867 infants were included. A single oral administration of clofibrate was associated with decreased need of phototherapy (RR:.38, 95% CI: 0.21 to 0.68), shortened duration of phototherapy (mean duration: 23.88 h, 95% CI: 33.03 to -14.72 h) and reduced peak total serum bilirubin (mean duration: -1.62 mg/dL, 95% CI: 2.13 to -1.11 mg/dL). These effects were especially obvious in term infants and infants without hemolytic diseases. Data regarding mortality or kernicterus were not available from included studies.

CONCLUSIONS

Clofibrate may have short-term benefits for the infants with hyperbilirubinaemia, especially for population of term infants and infants without hemolytic diseases. Large RCTs with long-term followup are required to verify the safety of clofibrate and assess its long-term effects.

Single dose of 50 mg/kg clofibrate in jaundice of healthy term neonates: randomised clinical trial of efficacy and safety

OBJECTIVE

To evaluate the effect of single oral dose of 50 mg/kg clofibrate in hyperbilirubinemia of term healthy neonates in Yazd, Iran.

METHODS

A parallel single- blinded randomized clinical trial, conducted on 60 healthy term neonates admitted between July and December 2007 to Shahid Sadoughi Hospital. Inclusion criteria were neonates with gestation age of 38-42 wk, birth weight of 2500-4000 g, product of normal vaginal delivery, breast-fed and total serum bilirubin (TSB) level of 17-29.9 mg/dL. Neonates with sepsis, anemia, severe asphyxia, hemolytic diseases, major congenital anomalies, indirect hyperbilirubinemia and underlying hepatic disorders were excluded. Selection of patients was based on random allocation via table of random numbers and the patients distributed into two groups. In group one, 30 neonates were treated with phototherapy alone and in 30 of other group treatment done with single dose of 50 mg/kg clofibrate and phototherapy. The primary endpoint with respect to efficacy in reducing of TSB was achieving TSB to less than 14 mg/dL as measured at the beginning, 12, 24 and 48 h after the start of phototherapy. Secondary outcomes were hospital stay days, duration of phototherapy and side effects of treatments during hospital stay and on the second day after discharge.

RESULTS

No significant differences were seen from the viewpoint of rout of delivery, gender, gestational age, birth weight, hemoglobin and bilirubin level at time of admission and weight in discharge time in the two groups. After 48 h of intervention, 27 (90%) neonates in clofibrate group and 15 (56.7%) in control group had TSB of less than 14 mg/dL (p 0.02). Mean TSB 12 h after treatment (mean ± SD: 14.82 ± 1.7 mg/dL vs. 16.67 ± 1.77 mg/dL, P 0.001), 24 h after treatment (mean ± SD: 11.97 ± 2.92 mg/dL vs. 14.61 ± 2.52 mg/dL, P 0.001) and 48 h after treatment (mean ± SD: 7.91 ± 2.45 mg/dL vs. 12.74 ± 2.21 mg/dL, P 0.0001), mean of hospital stay days (mean ± SD: 1.7 ± 0.7 days vs. 3.2 ± 1.2 days, P 0.03) and duration of phototherapy (mean ± SD: 30.2 ± 13.99 h vs. 46.2 ± 15.58 h, P 0.001] were significantly lower in clofibrate group. Only loose stool was seen in two patients of clofibrate group and no significant difference was seen from view of safety of the treatments.

CONCLUSIONS

A single dose of 50 mg/kg clofibrate in treatment of neonatal hyperbilirubinemia is effective, safe and cost effective in view of reducing hospital stay days.