Terazosin
| Evidence Level: L5 | Predicted Indications: 10 |
Table of Contents
- Terazosin
- Terazosin: From Hypertension and Benign Prostatic Hyperplasia to Hypotrichosis Simplex of the Scalp
Terazosin: From Hypertension and Benign Prostatic Hyperplasia to Hypotrichosis Simplex of the Scalp
One-Sentence Summary
Terazosin is an alpha-1 adrenergic blocker, originally used to treat hypertension and benign prostatic hyperplasia. The TxGNN model ranks hypotrichosis simplex of the scalp as its top predicted new indication, but no clinical trials and no publications currently support this prediction. Other predictions in the list, notably migraine and Raynaud disease, have limited older clinical reports and are better supported.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Hypertension; benign prostatic hyperplasia (from the knowledge graph, as the licence records contain no indication text) |
| Predicted New Indication | Hypotrichosis simplex of the scalp |
| TxGNN Prediction Score | 99.97% |
| Evidence Level | L5 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 5 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available in the data compiled for this report. Terazosin is known as a selective alpha-1 adrenergic receptor blocker. It relaxes vascular and prostatic smooth muscle, which explains its use in hypertension and benign prostatic hyperplasia.
The link to hair loss is speculative. One plausible but unproven idea is that vasodilation could improve scalp perfusion and follicle function, similar to minoxidil, another vasodilating antihypertensive. The high TxGNN score is a graph-based prediction only and does not reflect any observed clinical effect.
The other hair-related predictions are weaker still:
- Congenital hypotrichosis milia and Ambras-type hypertrichosis universalis congenita are rare genetic conditions with no mechanistic link to alpha-1 blockade. Ambras-type hypertrichosis is also the opposite phenotype (excess hair), which suggests the scores reflect graph artefacts.
- Diffuse alopecia areata is autoimmune, and alpha-1 blockade has no known direct immunomodulatory role.
- Alopecia has only one indirect review, which discusses extracardiac effects of cardiovascular drugs, mainly minoxidil.
The best-supported signals among the top 10 predictions are:
- Migraine disorder (rank 5, L3): alpha-1 blockade may modulate cerebrovascular tone and sympathetic activity. Evidence consists of a small 1994 open clinical study and a 1997 review, and has not been confirmed by modern randomised trials.
- Raynaud disease (rank 7, L3): alpha-1 blockade reduces sympathetically mediated vasoconstriction, which fits the pathophysiology. Evidence is a single 1997 study.
Clinical Trial Evidence
Currently no related clinical trials registered for the top-ranked prediction, or for any of the other nine predictions in the list.
Literature Evidence
There is no literature for the top-ranked prediction (hypotrichosis simplex of the scalp). The table below shows the publications found for other predicted indications.
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 9074296 | 1997 | Review | Headache | Ten migraine patients were given terazosin or doxazosin. Migraine frequency or severity fell in all but one, but five stopped treatment because of side effects (migraine) |
| 7911406 | 1994 | Open clinical study | La Clinica terapeutica | 46 patients with hemicrania without aura received terazosin (10), buflomedil (29) or both (7) for prophylaxis (migraine; also the only study cited for migraine with brainstem aura, where it is indirect) |
| 9273472 | 1997 | Clinical study | Minerva cardioangiologica | Terazosin reduced the number, intensity and duration of vasospastic attacks and improved thermographic and ultrasonographic findings in idiopathic and secondary Raynaud's phenomenon |
| 34779371 | 2022 | Review | Current cardiology reviews | Review of extracardiac effects of cardiovascular drugs, including minoxidil-related hair growth. Indirect evidence for alopecia only |
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN12672P | APO-TERAZOSIN TABLET 2 mg | Tablet | Not stated in the records |
| SIN11676P | HYTRIN TABLET 5 mg | Tablet | Not stated in the records |
| SIN11674P | HYTRIN TABLET 1 mg | Tablet | Not stated in the records |
| SIN11675P | HYTRIN TABLET 2 mg | Tablet | Not stated in the records |
| SIN11600P | TERASIN TABLET 2 mg | Tablet | Not stated in the records |
All five licences are valid single-ingredient oral tablets.
Safety Considerations
- Contraindication-related conditions (from the knowledge graph, not label text): multiple system atrophy, postural orthostatic tachycardia syndrome, orthostatic hypotension, priapism and intraoperative floppy iris syndrome.
- Drug Interactions: 100 interactions were identified. The listed ones are mostly Moderate severity, including:
- Corticosteroids: hydrocortisone, prednisone, prednisolone, dexamethasone, betamethasone, budesonide, triamcinolone
- Opioids: morphine (including liposomal) and opium
- SGLT2 inhibitors: canagliflozin, dapagliflozin, empagliflozin, ertugliflozin
- Cannabinoids: dronabinol and nabilone
- Bupropion
Interactions with calcitriol, pantoprazole and glimepiride have an unknown severity level.
- Tolerability: In the migraine report, five of ten patients stopped treatment because of side effects. Hypotension and dizziness are a particular concern in a mania population.
The package insert warnings and contraindications were not available, so please refer to the package insert for the full safety information.
Conclusion and Next Steps
Decision: Hold
Rationale: The top-ranked prediction, hypotrichosis simplex of the scalp, rests only on a graph-based score, with no trials or publications. The same is true of most other hair-related predictions. Migraine and Raynaud disease show some older, small-scale clinical signals, but they are not strong enough to move beyond a research question.
To proceed, the following is needed:
- Package insert warnings and contraindications from HSA, to complete the safety screening
- Mechanism of action data from DrugBank
- Any preclinical or clinical data on terazosin in hair-growth disorders, to test the speculative perfusion hypothesis
- For a more promising direction, a focused evidence review and a well-designed controlled study for migraine prophylaxis or Raynaud's phenomenon, with attention to hypotension and dizziness
- Assessment of route compatibility and formulation, since only oral tablets are registered in Singapore
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.