Aspartic Acid

證據等級: L5

預測適應症: 10 個

Aspartic Acid: From No Established Indication to Renal Tubular Acidosis

One-Sentence Summary

Aspartic acid (L-aspartate) is an endogenous, non-essential amino acid with fundamental roles in cellular metabolism, renal nitrogen transport, and tubular acid-base regulation, but it carries no formally approved therapeutic indication. The TxGNN model predicts it may be effective for Renal Tubular Acidosis (RTA), with 1 clinical trial retrieved (of negligible direct relevance) and 10 publications identified across basic, translational, and clinical literature. The mechanistic rationale is biologically coherent but the clinical evidence base is sparse, placing this prediction firmly at an early exploratory research stage.

Quick Overview

Item	Content
Original Indication	No established approved indication
Predicted New Indication	Renal Tubular Acidosis
TxGNN Prediction Score	99.47%
Evidence Level	L4
Singapore Market Status	Not Marketed
Number of Registrations	0
Recommended Decision	Hold

Why is This Prediction Reasonable?

Detailed mechanism of action data from DrugBank is currently unavailable. Based on established biochemistry, aspartic acid (aspartate) is a dicarboxylic amino acid central to the malate-aspartate shuttle, the urea cycle, and purine nucleotide synthesis. Its physiological relevance to the kidney is well-documented, though its potential as a therapeutic agent in renal tubular acidosis has not been formally evaluated in controlled trials.

Three mechanistic threads link aspartate to RTA pathophysiology. First, the transporter SLC22A13 catalyses unidirectional efflux of aspartate and glutamate specifically at the basolateral membrane of type A intercalated cells in the renal collecting duct, co-localising with anion exchanger 1 (AE1/Band 3/SLC4A1) — the very protein whose mutations cause distal RTA (PMID 24147638). This places aspartate transport at the centre of the cellular machinery responsible for proton secretion. Second, aspartate serves as a nitrogen donor in renal ammoniagenesis (PMID 14301365), the kidney's primary mechanism for buffering and excreting acid load; in chronically acidotic rats, concentrations of aspartate and related metabolic intermediates are significantly altered (PMID 5641145, PMID 2884989). Third, and most directly, a 1983 case report documents a child with pyruvate carboxylase deficiency, proximal RTA, and cystinuria whose clinical condition improved — including growth — following dietary supplementation with aspartic acid and asparagine (PMID 6422151). This is the only human observation of potential therapeutic benefit.

The TxGNN model's high score (99.47%) most likely reflects this deep embedding of aspartate in the renal tubular knowledge graph — many interacting proteins, transporters, and metabolic nodes connect aspartate to acid-base physiology. However, mechanistic relevance does not equal clinical efficacy, and the jump from biochemical role to therapeutic intervention remains unvalidated. The prediction is a biologically grounded hypothesis in need of prospective testing.

Clinical Trial Evidence

Trial Number	Phase	Status	Enrollment	Key Findings
NCT04725812	Phase 2	Terminated	2	Single-arm study of eculizumab (complement C5 inhibitor) for preeclampsia at 23–30 weeks gestation. Terminated with only 2 participants. Entirely unrelated to aspartic acid or RTA; database matching appears to be an error.

No clinical trials directly evaluating aspartic acid for renal tubular acidosis were identified.

Literature Evidence

PMID	Year	Type	Journal	Key Findings
6422151	1983	Case Report	J Inherited Metab Dis	A child with pyruvate carboxylase deficiency, proximal RTA, and cystinuria began to thrive when diet was supplemented with aspartic acid and asparagine — the only direct clinical observation linking aspartate to improvement in an RTA setting.
24147638	2014	Basic Research	Biochem J	SLC22A13 mediates unidirectional aspartate/glutamate efflux at the basolateral membrane of type A intercalated cells in the renal collecting duct, co-localising with AE1; directly implicates aspartate transport in the cells whose dysfunction underlies distal RTA.
990372	1976	Case Series	Biomedicine	Ornithine-aspartate infused intravenously in children from two families, one with hyperargininaemia and one with incomplete RTA plus cystinuria; explores serum amino acid kinetics following aspartate loading in an RTA context.
2884989	1987	Animal Study	Biochem J	¹³C NMR tracking of glutamate/aspartate carbon flux in rat renal tubules under chronic metabolic acidosis; reveals upregulated ammoniagenesis and altered aspartate utilisation in the acidotic kidney.
5641145	1968	Animal Study	Nature	Demonstrates significant changes in concentrations of metabolic intermediates, including aspartate, in kidneys of rats with metabolic acidosis — supporting a compensatory role in acid-base buffering.
14301365	1965	Physiology Study	Am J Physiol	Characterises the relationship between tubular cell pNH₃ and renal ammonia production; aspartate serves as a primary nitrogen donor in this acid-excreting process.
26208211	2015	Diagnostic Study	J Pediatria	Whole-exome sequencing used to confirm genetic diagnosis in four children with distal RTA — illustrates the genetic heterogeneity of dRTA and ongoing unmet diagnostic and therapeutic needs.
20068363	2010	Case Series	Nephron Physiol	SLC4A1 (AE1/Band 3) mutations causing distal RTA in Filipino children; the AE1 pathway co-localises with SLC22A13 aspartate transport, supporting a common mechanistic node.
12087557	2002	Case Report	Am J Kidney Dis	Autosomal recessive dRTA caused by G701D AE1 mutation — failure of basolateral Cl⁻/HCO₃⁻ exchange blocks H⁺ secretion in intercalated cells; contextualises the transporter environment where aspartate acts.
23053187	2013	Case Report	Ann Hematol	Band 3 A858D homozygote with hypokalaemic dRTA, compensated haemolysis, and acanthocytosis — further characterises the AE1/Band 3 phenotypic spectrum relevant to aspartate co-transport studies.

Singapore Market Information

Aspartic acid (DrugBank ID: DB00128) is not registered in Singapore. No product licences are on record. This drug would need to go through HSA's full registration process before any clinical use in Singapore.

Safety Considerations

Please refer to the package insert for safety information. No key warnings, contraindications, or drug interaction data were identified in the current evidence search.

Aspartic acid is a naturally occurring endogenous amino acid. At nutritional doses it is broadly regarded as safe. However, high-dose supplementation in the setting of renal impairment — which is inherent to RTA — warrants dedicated safety evaluation, as altered tubular function may affect both aspartate handling and downstream nitrogen metabolism.

Conclusion and Next Steps

Decision: Hold

Rationale: The TxGNN model's high prediction score (99.47%) reflects genuine, multi-layered biochemical connections between aspartate and renal tubular acid-base physiology — particularly the SLC22A13 transporter in intercalated cells and the role of aspartate in renal ammoniagenesis. However, the human clinical evidence amounts to a single 1983 case report in a complex metabolic disorder, and the one clinical trial retrieved is entirely off-target. With evidence at Level 4 (preclinical and mechanistic) and no controlled data, this candidate requires foundational validation before any forward-moving decision can be made.

To proceed, the following is needed:

Retrieve the full DrugBank MOA record for aspartic acid to confirm and extend the mechanistic rationale (resolve data gap DG002)
Download and review the relevant package insert or monograph to assess safety warnings and contraindications for renal disease populations (resolve data gap DG001)
Conduct a systematic literature search specifically on L-aspartate or ornithine-aspartate supplementation in metabolic acidosis and RTA animal models
Define the target RTA subtype (proximal type 2 vs. distal type 1; genetic vs. acquired/drug-induced) with the strongest mechanistic fit based on the SLC22A13–AE1 intercalated cell evidence
Commission a proof-of-concept preclinical study in a validated dRTA animal model to measure urinary pH, NH₄⁺ excretion, and serum bicarbonate following aspartate supplementation before considering any first-in-indication human study
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.