Homotaurine (tramiprosate)
Also called tramiprosate, 3-amino-1-propanesulfonic acid, 3-APS, Alzhemed, homotaurine supplement, valiltramiprosate.
Best grade D across 6 graded outcomes Other Last checked
The short answer
From 8 sourcesHomotaurine failed its large 78-week Alzheimer's trial on the planned outcomes, with only post-hoc signals in people carrying two APOE4 copies. A newer prodrug, valiltramiprosate, again missed its primary endpoint in 2025. Nausea and weight loss were the usual side effects; no supplement-dose trials give a proven benefit.
Every graded outcome on this page
6 rows · line = participants- DGrade DHippocampal volume loss on MRIBrain imagingn 312
- DGrade DCognition in APOE4/4 carriers with mild Alzheimer's disease (post-hoc re-analysis)Memory and cognitionn 257
- DGrade DHippocampal volume and episodic memory in amnestic MCIMemory and cognitionn 33
- DGrade DMotor, cognitive and sleepiness measures in Parkinson's diseaseSleepinessn 24
- ∅No effectCognition and daily function in mild-to-moderate Alzheimer's diseaseMemory and cognitionn 1,052
- ∅No effectCognition in early Alzheimer's disease with two APOE4 copiesMemory and cognitionn 325
- 3 more graded outcomes, in the evidence chapter
Key facts
What it is
Homotaurine is a taurine-like amino acid derivative from red algae, tested in Alzheimer's trials under the drug name tramiprosate.
Forms, side by side
2 forms named in our sources. The rest show what our data holds, and say plainly where it holds nothing yet.
Homotaurine (tramiprosate) forms compared
2 forms| 2 forms | Homotaurine / tramiprosate (oral) | Valiltramiprosate (ALZ-801), investigational prodrug |
|---|---|---|
| Absorption in people | Tramiprosate showed high variability in blood levels between people, attributed to extensive metabolism in the gut.7 | 265 mg twice daily gave the same steady-state tramiprosate exposure as 150 mg twice daily of tramiprosate, with lower variability and a longer half-life; food reduced GI symptoms without changing exposure.7 |
| GI tolerance | Mild-to-moderate nausea and vomiting were reported; mild gastrointestinal upset in 3 of the Parkinson's pilot patients.67 | Well tolerated in 127 healthy volunteers; transient mild nausea and some vomiting.7 |
| Studied for | Alzheimer's disease (100 to 150 mg twice daily), amnestic MCI, Parkinson's-related sleepiness (100 mg) | Early Alzheimer's disease in APOE4/4 carriers (265 mg twice daily, phase 3) |
- Homotaurine / tramiprosate (oral)
- Absorption in people
- Tramiprosate showed high variability in blood levels between people, attributed to extensive metabolism in the gut.7
- GI tolerance
- Mild-to-moderate nausea and vomiting were reported; mild gastrointestinal upset in 3 of the Parkinson's pilot patients.67
- Studied for
- Alzheimer's disease (100 to 150 mg twice daily), amnestic MCI, Parkinson's-related sleepiness (100 mg)
- Valiltramiprosate (ALZ-801), investigational prodrug
- Absorption in people
- 265 mg twice daily gave the same steady-state tramiprosate exposure as 150 mg twice daily of tramiprosate, with lower variability and a longer half-life; food reduced GI symptoms without changing exposure.7
- GI tolerance
- Well tolerated in 127 healthy volunteers; transient mild nausea and some vomiting.7
- Studied for
- Early Alzheimer's disease in APOE4/4 carriers (265 mg twice daily, phase 3)
What the human research says
Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.
Trial map
6 graded outcomes, largest study first6 graded outcomes: 2 improved, 1 mixed, 3 no effect. The largest, a 2011 randomized trial of 1,052 people on cognition and daily function in mild-to-moderate Alzheimer's disease, found no effect.
1Cognition and daily function in mild-to-moderate Alzheimer's disease
No effect · No-effect grade · RCT, 1,052 people, 2011
Adults aged 50+ with mild-to-moderate Alzheimer's disease (MMSE 16 to 26) on stable cholinesterase inhibitors, with or without memantine
Dose, result and source| Outcome | Found | People | Study | Who was studied |
|---|---|---|---|---|
| Cognition and daily function in mild-to-moderate Alzheimer's disease | No effect | 1,052 | No-effect grade · RCT, 2011 | Adults aged 50+ with mild-to-moderate Alzheimer's disease (MMSE 16 to 26) on stable cholinesterase inhibitors, with or without memantine |
| Cognition in early Alzheimer's disease with two APOE4 copies | No effect | 325 | No-effect grade · RCT, 2025 | Adults aged 50 to 80 with early symptomatic Alzheimer's disease and APOE4/4 genotype (MMSE 22 to 30) |
| Hippocampal volume loss on MRI | Mixed | 312 | Grade D · RCT, 2009 | MRI subgroup of the Alphase trial: 312 patients with usable scan pairs |
| Cognition in APOE4/4 carriers with mild Alzheimer's disease (post-hoc re-analysis) | Improved | 257 | Grade D · RCT, 2017 | APOE4/4 homozygotes (147 and 110 across two phase 3 trials); mild subgroup MMSE 22 to 26 |
| Hippocampal volume and episodic memory in amnestic MCI | Improved | 33 | Grade D · Observational, 2016 | Adults with amnestic mild cognitive impairment: 11 treated, 22 untreated |
| Motor, cognitive and sleepiness measures in Parkinson's disease | No effect | 24 | Grade D · Pilot RCT, 2015 | Adults with Parkinson's disease and cognitive impairment (47 enrolled, 24 completed and analysed per protocol) |
Every graded row
6 rowsShowing 6 of 6 outcomes. Human trials only.
DGrade DHippocampal volume loss on MRIBrain imagingLess hippocampal shrinkage in post-hoc models; no clinical matchRCT
n 312 · 2009
Mixed Revised-model analyses (not the planned ones) showed less hippocampal volume loss with 100 mg (P = 0.035) and 150 mg (P = 0.009) than placebo, in a dose-response pattern. Changes in psychometric scores and hippocampal volume were not significantly correlated; CDR-SB showed no differences.
- Design
- RCT, n = 312, 2009
- Population
- MRI subgroup of the Alphase trial: 312 patients with usable scan pairs
- Form
- Tramiprosate (homotaurine)
- Dose
- 100 mg or 150 mg twice daily
- Duration
- 78 weeks
- Source
- Reference 2 · PubMed 19536424 (opens PubMed)
DGrade DCognition in APOE4/4 carriers with mild Alzheimer's disease (post-hoc re-analysis)Memory and cognitionPost-hoc benefit in a small genetic subgroupRCT
n 257 · 2017
Improved In APOE4/4 homozygotes on 150 mg twice daily, benefits over placebo on ADAS-cog, CDR-SB and DAD were 125%, 81% and 71% (p < 0.02); the MMSE 22 to 26 subgroup stabilised with no decline over 78 weeks. Common adverse events were nausea, vomiting, depression and decreased weight.
- Design
- RCT, n = 257, 2017
- Population
- APOE4/4 homozygotes (147 and 110 across two phase 3 trials); mild subgroup MMSE 22 to 26
- Form
- Tramiprosate (homotaurine)
- Dose
- 150 mg twice daily
- Duration
- 78 weeks
- Source
- Reference 3 · PubMed 29182706 (opens PubMed)
DGrade DHippocampal volume and episodic memory in amnestic MCIMemory and cognitionLess regional brain volume loss vs untreated patientsObservational
n 33 · 2016
Improved Treated patients showed decreased volume loss in the left and right hippocampal tail, fusiform gyri and right inferior temporal cortex, linked to better short-term episodic memory (recency effect of the Rey 15-word list).
- Design
- Observational, n = 33, 2016
- Population
- Adults with amnestic mild cognitive impairment: 11 treated, 22 untreated
- Form
- Homotaurine
- Dose
- Dose not stated in the abstract
- Duration
- 1 year
- Source
- Reference 5 · PubMed 26757035 (opens PubMed)
DGrade DMotor, cognitive and sleepiness measures in Parkinson's diseaseSleepinessNo between-group difference; within-group sleepiness gainPilot RCT
n 24 · 2015
No effect Per-protocol analysis showed no difference between groups. Within the homotaurine group, UPDRS-I (p = 0.017) and Epworth Sleepiness Scale (p = 0.01) improved from baseline. Mild gastrointestinal upset occurred in 3 patients; 51% completed.
- Design
- Pilot RCT, n = 24, 2015
- Population
- Adults with Parkinson's disease and cognitive impairment (47 enrolled, 24 completed and analysed per protocol)
- Form
- Homotaurine
- Dose
- 100 mg (schedule not stated)
- Duration
- 6 months
- Source
- Reference 6 · PubMed 25894843 (opens PubMed)
∅No effectCognition and daily function in mild-to-moderate Alzheimer's diseaseMemory and cognitionNo significant benefit on the planned cognitive or functional outcomesRCT
n 1,052 · 2011
No effect The planned analyses showed no significant differences between groups on ADAS-cog or CDR-SB. Revised models showed only a trend for ADAS-cog (P = 0.098). Adverse event rates were similar across groups; 790 of 1,052 (75.1%) completed.
- Design
- RCT, n = 1,052, 2011
- Population
- Adults aged 50+ with mild-to-moderate Alzheimer's disease (MMSE 16 to 26) on stable cholinesterase inhibitors, with or without memantine
- Form
- Tramiprosate (homotaurine)
- Dose
- 100 mg or 150 mg twice daily
- Duration
- 78 weeks
- Source
- Reference 1 · PubMed 22291741 (opens PubMed)
∅No effectCognition in early Alzheimer's disease with two APOE4 copiesMemory and cognitionPrimary endpoint missed; imaging and MCI subgroup signalsRCT
n 325 · 2025
No effect The overall population showed no significant effect on ADAS-Cog13 (11% slowing; p = 0.607) but 18% slower hippocampal atrophy (p = 0.017). No significant clinical effects in mild AD. In the prespecified MCI group (N = 125), ADAS-Cog13 (52%, nominal p = 0.041) and DAD (96%, nominal p = 0.016) favoured the drug. Nausea, vomiting and decreased appetite occurred at more than double the placebo rate.
- Design
- RCT, n = 325, 2025
- Population
- Adults aged 50 to 80 with early symptomatic Alzheimer's disease and APOE4/4 genotype (MMSE 22 to 30)
- Form
- Valiltramiprosate (ALZ-801, prodrug)
- Dose
- 265 mg twice daily
- Duration
- 78 weeks
- Source
- Reference 4 · PubMed 41015981 (opens PubMed)
What the numbers add up to
Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.
Scans moved, symptoms did not
The strongest signal is a small subgroup
Studied doses
Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.
Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.
Doses studied in human trials
Interactions and safety
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
What Homotaurine meets
1 cited rowMedicines 1
Supplements and foods 0
No supplement rows in our sources.
- Measured in a human study
Choose a medicine or supplement above to read its cited rows here.
Also cited:
Cholinesterase inhibitors and memantine
RCTMeasured in a human study
Cholinesterase inhibitors and memantine: Alphase participants stayed on stable doses of these Alzheimer's drugs; adverse events were similar across groups. The trial was not designed as an interaction study.
Source 1, Arch Med Sci (2011)
Interactions
1 agent| Agent | What the source says | Evidence |
|---|---|---|
| Medicines1 | ||
| Cholinesterase inhibitors and memantine | Alphase participants stayed on stable doses of these Alzheimer's drugs; adverse events were similar across groups. The trial was not designed as an interaction study.1 | RCT |
Check with what you take
Kept on this device onlyAdd what you take. We list every interaction our evidence profiles cite between Homotaurine and your picks, and between your picks.
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Add a supplement or medicine you take to check it against Homotaurine.
Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.
Who should be careful
4 groups- Nausea-prone or low-appetite adults
- Nausea, vomiting and decreased appetite were the commonest adverse events, at more than double the placebo rate in the 2025 prodrug trial; decreased weight and depression also appeared in the earlier APOE4/4 analysis.34
- Expecting a proven memory benefit
- The 78-week Alphase trial did not meet its planned analyses, and the 2025 phase 3 prodrug trial did not slow cognitive decline overall. Supplement-dose evidence is limited to small, uncontrolled or post-hoc studies.14
- People with a dementia diagnosis
- Anyone with Alzheimer's disease or Parkinson's disease should discuss any supplement with their care team; the trials involved patients on stable standard drugs.16
- Pregnancy, breastfeeding and children
- No studies in these groups were found in the sources reviewed, so safety is unknown.1
How to read the label
What to check on the Supplement Facts panel.
How to read the label
2 checksLabel dose vs trial dose
Frequently asked questions
Short answers to common questions; the numbers link to the sources below.
Common questions
6 answersWhat is homotaurine?
Did homotaurine work in Alzheimer's trials?
What about the APOE4/4 results?
What are the side effects?
Is homotaurine the same as valiltramiprosate?
Does homotaurine help Parkinson's disease?
A 6-month single-blind pilot found no difference between groups in per-protocol analysis; sleepiness scores improved within the homotaurine group. Half of patients dropped out.6
Sources
8 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.
Sources cited on this page
8 sources- 1Tramiprosate in mild-to-moderate Alzheimer's disease - a randomized, double-blind, placebo-controlled, multi-centre study (the Alphase Study).RCT Arch Med Sci, 2011 · PMID 22291741
- 2Effect of tramiprosate in patients with mild-to-moderate Alzheimer's disease: exploratory analyses of the MRI sub-group of the Alphase study.RCT J Nutr Health Aging, 2009 · PMID 19536424
- 3Clinical Effects of Tramiprosate in APOE4/4 Homozygous Patients with Mild Alzheimer's Disease Suggest Disease Modification Potential.RCT J Prev Alzheimers Dis, 2017 · PMID 29182706
- 4Clinical Efficacy, Safety and Imaging Effects of Oral Valiltramiprosate in APOEε4/ε4 Homozygotes with Early Alzheimer's Disease: Results of the Phase III, Randomized, Double-Blind, Placebo-Controlled, 78-Week APOLLOE4 Trial.RCT Drugs, 2025 · PMID 41015981
- 5Homotaurine Effects on Hippocampal Volume Loss and Episodic Memory in Amnestic Mild Cognitive Impairment.Observational J Alzheimers Dis, 2016 · PMID 26757035
- 6Homotaurine in Parkinson's disease.Pilot RCT Neurol Sci, 2015 · PMID 25894843
- 7Clinical Pharmacokinetics and Safety of ALZ-801, a Novel Prodrug of Tramiprosate in Development for the Treatment of Alzheimer's Disease.PK study Clin Pharmacokinet, 2018 · PMID 29063518
- 8ALZ-801 (valiltramiprosate): therapeutics entryDatabase Alzforum, 2026 · alzforum.org
What changed
Every dated change to this page: what changed, who made it and why.
Change log
2 entries| Date | Change | Who and why |
|---|---|---|
| evidence | Adversarial review: Parkinson's pilot n set to the 24 per-protocol completers (was the 47 enrolled) and regraded no-effect to D (too small to show no effect). Sponsor ties of the 2017 and 2025 papers confirmed from their PubMed conflict-of-interest statements; other rows match their abstracts. | Writer: Kymata Health EditorialTrigger: adversarial review |
| all | Initial editorial evidence review. Every PMID checked against NCBI E-utilities esummary (title, year, journal) and each cited abstract read; figures taken from the abstracts. Status of ALZ-801 from the Alzforum therapeutics entry and the 2025 APOLLOE4 publication. Authors of the post-hoc and phase 3 prodrug papers are sponsor-affiliated. | Writer: Kymata Health EditorialTrigger: new page |
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