Acetylcysteine
| Evidence Level: L2 | Predicted Indications: 10 |
Table of Contents
Acetylcysteine: From Bronchitis and Paracetamol Poisoning to Thrombotic Disease
One-Sentence Summary
Acetylcysteine is a mucolytic and antioxidant, originally used for respiratory conditions such as bronchitis, cystic fibrosis and bronchiectasis, and as an antidote for paracetamol poisoning. The TxGNN model predicts it may be effective for thrombotic disease, with 7 clinical trials and 20 publications currently supporting this direction. Most of the evidence concerns thrombotic microangiopathies (TTP and transplant-associated TMA) rather than thrombosis in general.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Bronchitis, paracetamol poisoning, cystic fibrosis, bronchiectasis, amyloidosis (per the knowledge graph; no approved indication text is available from Singapore licences) |
| Predicted New Indication | Thrombotic disease |
| TxGNN Prediction Score | 99.96% |
| Evidence Level | L2 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 16 |
| Recommended Decision | Proceed with Guardrails |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available for this drug. Based on known information, acetylcysteine is a thiol-containing reducing agent with antioxidant activity. Its efficacy as a mucolytic, where it breaks disulfide bonds in mucus, is well established.
The same chemistry may apply to thrombosis. Acetylcysteine can reduce disulfide bonds in ultra-large von Willebrand factor (VWF) multimers, lowering their platelet-binding activity. This offers a plausible mechanism for thrombotic microangiopathies such as thrombotic thrombocytopenic purpura (TTP) and transplant-associated thrombotic microangiopathy (TA-TMA). Its antioxidant activity may also reduce platelet activation and the prothrombotic state seen in renal insufficiency. Preclinical mouse and baboon models of TTP support the VWF-reduction mechanism.
Note that the link between the original respiratory and antidote uses and thrombosis is mechanistic (thiol chemistry and redox effects) rather than based on a shared disease area.
Clinical Trial Evidence
| Trial Number | Phase | Status | Enrollment | Key Findings |
|---|---|---|---|---|
| NCT03252925 | Phase 3 | Completed | 170 | Safety and efficacy of NAC in transplant-associated TMA; results not available in the compiled data |
| NCT07279610 | Phase 2/3 | Active, not recruiting | 44 | Single-arm study of NAC in transplant-associated TMA; results pending |
| NCT03636932 | Phase 2 | Completed | 40 | Randomized, double-blind, placebo-controlled crossover trial of NAC to reduce the thrombotic phenotype in renal insufficiency |
| NCT04368598 | Phase 2 | Unknown | 44 | NAC plus high-dose dexamethasone in newly diagnosed immune thrombocytopenia (indirect relevance) |
| NCT01808521 | Early Phase 1 | Completed | 3 | Pilot of intravenous NAC in suspected TTP; too small to support conclusions |
| NCT05551624 | Early Phase 1 | Completed | 15 | Atorvastatin plus NAC on platelet count in immune thrombocytopenia (loosely related) |
| NCT03460808 | Phase 1/2 | Unknown | 200 | Atorvastatin, NAC and danazol in steroid-resistant or relapsed immune thrombocytopenia (NAC effect cannot be isolated) |
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 41977015 | 2026 | Systematic Review | J Clin Med | Systematic review and critical appraisal of NAC in TTP |
| 42338865 | 2026 | Systematic Review | Cureus | Systematic review of NAC as adjunctive therapy in TTP |
| 37311880 | 2023 | Cohort study | Ann Hematol | Retrospective cohort examining NAC and in-hospital mortality in acquired TTP; NAC use remains controversial |
| 28011677 | 2017 | Preclinical | Blood | NAC tested in mouse and baboon TTP models, supporting the VWF-reduction mechanism |
| 32243196 | 2020 | Review | Expert Rev Hematol | Reviews repurposed drugs for TTP, including NAC |
| 28416507 | 2017 | Review | Blood | Overview of TTP pathophysiology and management |
| 33540569 | 2021 | Review | J Clin Med | TTP pathophysiology, diagnosis and management |
| 32614622 | 2021 | Review | Platelets | Novel antiplatelet strategies targeting VWF and GPIb |
| 36410267 | 2022 | Review | J Infect Public Health | NAC in COVID-19, including its prothrombotic state |
| 34448938 | 2021 | Review | Lung | Thiols in COVID-19, including thrombosis linked to oxidative stress |
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN03414P | Fluimucil Granules 100 mg/sachet | Granule | Not available |
| SIN07474P | Fluimucil A 600 Effervescent Tablet 600 mg | Tablet | Not available |
| SIN16305P | Mucodex Powder for Solution 100 mg/sachet | Powder, for solution | Not available |
| SIN14971P | Mentopin Acetylcysteine Effervescent Tablet 600 mg | Effervescent tablet | Not available |
| SIN12497P | Spatam Capsule 200 mg | Capsule | Not available |
All 16 registrations are valid single-ingredient products. Only five are shown here.
Safety Considerations
- Knowledge-graph contraindication signals (not label text): peptic ulcer disease, hypotensive disorder, respiratory failure, asthma, bronchial disease, esophageal varices.
- Drug Interactions: 100 interactions were found in total. The listed ones include activated charcoal (Minor) and inhaled rapid-acting human insulin (Moderate). Many others, such as mannitol, bupropion, metformin, omeprazole, morphine and prednisone, have no assigned severity level.
Please refer to the package insert for full warnings and contraindications.
Conclusion and Next Steps
Decision: Proceed with Guardrails
Rationale: The main support is a completed Phase 3 trial in transplant-associated TMA (NCT03252925), several smaller trials, and a plausible VWF-reduction mechanism backed by preclinical TTP models. The Phase 3 results are not in the compiled data and only one such trial exists, so the evidence is L2, not L1. The evidence also covers thrombotic microangiopathies rather than thrombotic disease broadly, and acetylcysteine is already marketed in Singapore.
To proceed, the following is needed:
- Published results of NCT03252925 and the ongoing NCT07279610, to confirm efficacy
- Narrowing the target indication to TTP or TA-TMA rather than thrombotic disease generally
- Singapore package insert warnings and contraindications
- Detailed mechanism of action data
- A review of the knowledge-graph contraindications (asthma, respiratory failure, peptic ulcer, esophageal varices, hypotension) for the target population
- Checking whether the intravenous or high-dose regimens used in the trials are available in Singapore. The registered products are oral granules, powders, tablets and capsules.
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.