Lactic Acid

Evidence Level: L5

Predicted Indications: 10

Lactic Acid
Lactic Acid: From an Endogenous Metabolite and Topical/Infusion Agent to Atypical Coarctation of Aorta

## Pharmacist Assessment Report

Lactic Acid: From an Endogenous Metabolite and Topical/Infusion Agent to Atypical Coarctation of Aorta

One-Sentence Summary

Lactic acid is an endogenous metabolite used in Singapore in topical products and as part of an intravenous infusion (compound sodium lactate). The TxGNN model predicts it may be effective for atypical coarctation of aorta, but this is a network-based prediction only, with 0 clinical trials and 0 publications for this indication. Of the 10 predicted indications, none has direct therapeutic evidence, so this is a weak repurposing candidate.

Quick Overview

Item	Content
Original Indication	Not stated in the approved indication text of the Singapore licences
Predicted New Indication	Atypical coarctation of aorta
TxGNN Prediction Score	99.59%
Evidence Level	L5
Singapore Market Status	✓ Marketed
Number of Registrations	3
Recommended Decision	Hold

Why is This Prediction Reasonable?

Currently, detailed mechanism of action data is not available. Lactic acid is an endogenous metabolite (the end product of glycolysis) and is used as a topical and pH-adjusting agent. It also appears as lactate in intravenous fluid.

For atypical coarctation of aorta, no mechanistic link was identified. This is a structural developmental anomaly of the aorta, and lactic acid has no known role in aortic development or in treating vascular malformations. The high TxGNN score (99.59%) reflects network proximity in the knowledge graph rather than biological or clinical rationale.

The other top-ranked predictions were also reviewed, and none shows therapeutic support:

Aortic malformation: The 14 retrieved papers concern congenital heart surgery, biodegradable devices made of poly-lactic acid, and perioperative monitoring. None tests lactic acid as a treatment.
Dry eye syndrome (L4): The evidence concerns lactic acid bacteria (probiotics) in mouse models and metabolomic biomarkers, not lactic acid itself.
Esophageal disease and eye disease: The literature includes adverse signals. Indole-3-lactic acid suppressed anti-PD-1 efficacy in esophageal squamous cell carcinoma, and lactic acid upregulated VEGF and promoted choroidal neovascularization in preclinical work.
Amenorrhea: The only paper is a baboon vaginal microbiota study, which is not a treatment link.
Non-syndromic esophageal malformation, complex double outlet right ventricle, lacrimal excretory anomaly and cauda equina syndrome: Prediction only, with no mechanistic rationale, trials or literature.

Clinical Trial Evidence

Currently no related clinical trials registered.

Literature Evidence

No literature was retrieved for atypical coarctation of aorta. The closest related set, for aortic malformation (rank 2), contained no study of lactic acid as a therapy. The most relevant items are listed below for context only.

PMID	Year	Type	Journal	Key Findings
3367436	1988	Preclinical/Animal	Journal of Vascular Surgery	Aortic wall respiration and glycolysis above and below an experimental coarctation in rabbits on standard or atherogenic diets; a metabolic study, not a lactic acid treatment
25157439	2015	Preclinical/Animal	Catheterization and Cardiovascular Interventions	Biodegradable poly-l-lactic acid stent in rabbit descending aorta; a device material, not a drug effect
32382764	2020	Case report	Pediatric Cardiology	Absorbable poly-l-lactic acid microplates for bronchomalacia in infants with congenital heart disease; device material
23791497	2013	RCT	Journal of Cardiothoracic and Vascular Anesthesia	Combined ultrafiltration strategy in pediatric cardiac surgery; unrelated to lactic acid

Singapore Market Information

Authorization Number	Product Name	Dosage Form	Approved Indication
SIN04047P	DUOFILM COLLODION	Tincture	Not stated
SIN04987P	SATO UONOME SOLUTION	Solution	Not stated
SIN06281P	COMPOUND SODIUM LACTATE INTRAVENOUS INFUSION BP	Injection	Not stated

Safety Considerations

Drug Interactions: 17 interactions were identified (DDInter source). None is rated major.
- Moderate (10): doxycycline, tetracycline, minocycline, demeclocycline, oxytetracycline, acetylsalicylic acid, sodium salicylate, ephedrine (including nasal), pseudoephedrine.
- Minor (7): chlorpropamide, tolazamide, glipizide, glyburide, acetohexamide, tolbutamide, methotrexate.
Signals from the literature (preclinical or case-level, not label data): lactic acid-related signalling has been linked to promotion of choroidal neovascularization and immunosuppression in the tumour microenvironment. A case of ectropion followed over-the-counter acid treatment of xanthelasma. These argue for caution in the eye and oesophagus indications.

Please refer to the package insert for warnings and contraindications.

Conclusion and Next Steps

Decision: Hold

Rationale: The prediction rests only on a knowledge-graph score. There are no trials, no literature on lactic acid in this condition, and no plausible mechanism for a structural aortic anomaly. None of the other nine predicted indications has therapeutic evidence either, and some show potential harm signals.

To proceed, the following is needed:

Package insert warnings and contraindications from the HSA website (this gap blocks safety screening)
Mechanism of action data from DrugBank
Approved indication text for the three Singapore licences, to establish the original indication
A plausible pharmacological rationale for the predicted indication, and preclinical evidence supporting it
Route compatibility assessment, since the available forms (topical and intravenous) have not been matched to what the condition would require
If any indication is pursued, dry eye is the only one with some (indirect) evidence at L4, and it would first need direct tests of lactic acid itself rather than probiotics
Disclaimer

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