Formulation and Clinical Evaluation of Sodium Benzoate Oral Solution for the Treatment of Urea Cycle Disorders in Pediatric Patients

A validated stability‐indicating reversed‐phase‐UPLC method for simultaneous estimation of promethazine hydrochloride, methylparaben, propylparaben and sodium benzoate assay of cough suppressant and antihistamine liquid oral dosage forms

A quick, simple, sensitive, efficient and stability-indicating reverse-phase ultraperformance liquid chromatographic method for the estimation of propylparaben, methylparaben and sodium benzoate in a pharmaceutical liquid oral formulation was developed. A Waters Acquity UPLC BEH C18, 50 × 2.1 mm, 1.7 μm i.d. column was used to perform chromatographic separation with a 0.1% perchloric acid mobile phase used as solvent A and a mixture of 0.1 % perchloric acid and methanol in the ratio 20:80 (v/v), respectively, as solvent B. The experiments were carried out at a flow rate of 0.4 ml/min and the detection wavelength was 240 nm. The compartment temperature of the column was set at 40°C and the injection volume was set at 2 μl. The main aim of the research was to develop a single UPLC assay method for promethazine (active ingredient) and preservatives in the oral solution of promethazine HCl and dextromethorphan HBr that contains promethazine (active ingredient) and methylparaben, propylparaben and sodium benzoate (preservatives). An assay of dextromethorphan HBr was developed and validated by another HPLC method. The drug and preservatives were eluted at retention times of 19.3 min for promethazine HCl, 9.3 min for methylparaben, 18.9 min for propylparaben and 8.9 min for sodium benzoate. Validation of the developed method was carried out as stated by the International Conference on Harmonization guidelines ICH Q2B and under USP<1225>. The analytical parameters verified specificity/selectivity, linearity, accuracy, ruggedness and robustness. The linearity ranges of promethazine HCL, methylparaben, propylparaben and sodium benzoate were 10-100, 10-80, 1.0-8.0 and 10-80 μg/ml, respectively, with a correlation coefficient of active ingredients and preservatives of 1.00. Percentage recoveries of promethazine, propylparaben, methylparaben, and sodium benzoate were 100.0-100.2, 99.0-100.3, 99.5-98.0 and 99.0-100.0%. The validated analytical method proves that the method is specific, precise, linear, accurate, sensitive, rugged and stable, indicating the quantification of the active ingredient and all preservatives in liquid oral formulations.

Mitochondrial targets in hyperammonemia: Addressing urea cycle function to improve drug therapies

The urea cycle (UC) is a critically important metabolic process for the disposal of nitrogen (ammonia) produced by amino acids catabolism. The impairment of this liver-specific pathway induced either by primary genetic defects or by secondary causes, namely those associated with hepatic disease or drug administration, may result in serious clinical consequences. Urea cycle disorders (UCD) and certain organic acidurias are the major groups of inherited rare diseases manifested with hyperammonemia (HA) with UC dysregulation. Importantly, several commonly prescribed drugs, including antiepileptics in monotherapy or polytherapy from carbamazepine to valproic acid or specific antineoplastic agents such as asparaginase or 5-fluorouracil may be associated with HA by mechanisms not fully elucidated. HA, disclosing an imbalance between ammoniagenesis and ammonia disposal via the UC, can evolve to encephalopathy which may lead to significant morbidity and central nervous system damage. This review will focus on biochemical mechanisms related with HA emphasizing some poorly understood perspectives behind the disruption of the UC and mitochondrial energy metabolism, namely: i) changes in acetyl-CoA or NAD+ levels in subcellular compartments; ii) post-translational modifications of key UC-related enzymes, namely acetylation, potentially affecting their catalytic activity; iii) the mitochondrial sirtuins-mediated role in ureagenesis. Moreover, the main UCD associated with HA will be summarized to highlight the relevance of investigating possible genetic mutations to account for unexpected HA during certain pharmacological therapies. The ammonia-induced effects should be avoided or overcome as part of safer therapeutic strategies to protect patients under treatment with drugs that may be potentially associated with HA.

Treatment and management for children with urea cycle disorder in chronic stage

Urea cycle disorder (UCD) is a group of inherited metabolic diseases with high disability or fatality rate, which need long-term drug treatment and diet management. Except those with Citrin deficiency or liver transplantation, all pediatric patients require lifelong low protein diet with safe levels of protein intake and adequate energy and lipids supply for their corresponding age; supplementing essential amino acids and protein-free milk are also needed if necessary. The drugs for long-term use include nitrogen scavengers (sodium benzoate, sodium phenylbutyrate, glycerol phenylbutyrate), urea cycle activation/substrate supplementation agents (N-carbamylglutamate, arginine, citrulline), etc. Liver transplantation is recommended for pediatric patients not responding to standard diet and drug treatment, and those with severe progressive liver disease and/or recurrent metabolic decompensations. Gene therapy, stem cell therapy, enzyme therapy and other novel technologies may offer options for treatment in UCD patients. The regular biochemical assessments like blood ammonia, liver function and plasma amino acid profile are needed, and physical growth, intellectual development, nutritional intake should be also evaluated for adjusting treatment in time.

Identification of a novel homozygous intron 3 splice site (A>T) mutation in the ARG1 gene in cerebral palsy pediatric cases from Odisha, India

BACKGROUND

Arginase enzyme is essential for the catalysis of the last step of the urea cycle, resulting in the conversion of L-arginine to L-ornithine and urea. Arginase deficiency could lead to hyperarginemia, an autosomal recessive disorder of the urea cycle that could result in developmental manifestations after the first year of life, followed by gradually progressive atonic cerebral palsy, spastic quadriplegia, and mental decline. ARG1 mutations have been reported in hyperarginemia patients of Western countries because they exhibited reduced arginase activity. Hence, it is important to assess ARG1 mutations in cerebral palsy cases with hyperarginemia in different populations.

METHODS AND RESULTS

This study involved two unrelated pediatric patients from two non-consanguineous East Indian families, exhibiting a range of manifestations, including hypotonia of all limbs, mental retardation, and multiple episodes of seizure. The onset of the disease ranged from 1 to 3 years of age. Hyperammonemia (> 250 micromoles) and serum hyperarginemia (> 350 micromoles) were observed in both the patients. Whole-genome sequencing, followed by Sanger sequencing of both the patients confirmed the presence of a homozygous 3' splice site variation in intron 3 of the ARG1 gene (chr6: g.131902357A>T) that affects the invariant AG acceptor splice site of exon 4 (c.330-2A>T; ENST00000356962.2).

CONCLUSION

The study reported the identification of a novel ARG1 mutation in two different unrelated pediatric cases from Odisha, India associated with hyperarginemia. The pathogenicity of the mutation was robustly supported by the clinical phenotype, complete co-segregation with the disease, and biochemical observations.

The burden of pharmacological treatment on health-related quality of life in people with a urea cycle disorder: a qualitative study

BACKGROUND

Urea cycle disorders (UCD) are inborn errors of metabolism, typically presenting neonatally. Excess ammonia builds rapidly within the body risking hyperammonemic episodes and potentially death. Long-term management of the condition includes restrictive protein consumption, pharmacological interventions and, in extreme cases, liver transplantation. Pharmacological treatments such as sodium benzoate and sodium phenylbutyrate have proven effective but not without a multitude of negative attributes including poor taste, higher dosage and associated gastrointestinal discomfort that impacts health-related quality of life. Glycerol phenylbutyrate (GPB) has recently become a widely available pharmacological treatment with early reports of improved qualities, including taste and administration method. The following study aims to explore the burden of pharmacological treatment and the effects of the transition to GPB on health-related quality of life in people with a UCD.

RESULTS

Nine carers of children living with a UCD (mean age = 12.44, SD = 10.26) were interviewed regarding their experiences of pharmacological treatment in relation to their, and their child's, health-related quality of life after transitioning to GPB. Three main themes were identified: psychological health, physical health and social participation. Carers struggled with anxiety surrounding their child's condition and the battle of administering medication. Medication administration was perceived to have improved since the transition to GPB, alleviating distress for both carer and child. Issues involving school were described, ranging from difficulties integrating their child into mainstream schooling and the impact of treatment on participation in school and extracurricular activities. Carers encountered issues sourcing syringes to administer GPB, which induced stress. It could be suggested that some burden had been relieved by the transition to GPB. However, it appeared that difficulties associated with the illness would persist despite treatment, owing to the continuing nature of the condition.

CONCLUSIONS

Adhering to a strict pharmacological regime caused immense stress for both carers and children, severely impacting on typical social activities such as eating at a restaurant or going on holiday. GPB was perceived to have alleviated some burden in terms of administration given improved characteristics concerning taste and dosage, important characteristics for both carers and children living with UCD. Practitioners should consider these findings when making clinical decisions for children with UCD and the effect of pharmacological treatment on carer's health-related quality of life. Outreach work to facilitate greater understanding of the condition should be conducted with key locations, such as children's schools. This would also help to alleviate carer burden.