Phenoxybenzamine
| Evidence Level: L5 | Predicted Indications: 2 |
Table of Contents
- Phenoxybenzamine
- Phenoxybenzamine: From Pheochromocytoma-Related Hypertension to Primary Hereditary Glaucoma
Phenoxybenzamine: From Pheochromocytoma-Related Hypertension to Primary Hereditary Glaucoma
One-Sentence Summary
Phenoxybenzamine is a non-selective, irreversible alpha-adrenergic receptor antagonist, historically used to manage pheochromocytoma-related hypertension and peripheral vasospasm (this original indication is inferred from its DrugBank pharmacological classification, as confirmed original-indication data is currently a gap). The TxGNN model predicts it may be effective for Primary Hereditary Glaucoma, but this direction is currently supported by 0 clinical trials and 0 publications — it is a pure model-based prediction with no corroborating evidence.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Pheochromocytoma-related hypertension / peripheral vasospasm (inferred from drug class; confirmed indication text unavailable) |
| Predicted New Indication | Primary Hereditary Glaucoma |
| TxGNN Prediction Score | 99.55% |
| Evidence Level | L5 |
| India Market Status | Not Marketed |
| Number of Registrations | 0 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available (Data Gap DG002). Based on its DrugBank (DB00925) pharmacological classification, phenoxybenzamine is known to act as a non-selective, irreversible α-adrenergic receptor antagonist, traditionally used to control hypertension and peripheral vascular spasm associated with pheochromocytoma.
The proposed link to glaucoma is theoretical: α1-receptor antagonism could, in principle, relax vascular smooth muscle in the trabecular meshwork or ciliary body and thereby influence aqueous humor outflow. However, this is a speculative pathway rather than a validated mechanism for intraocular pressure (IOP) reduction — clinically established IOP-lowering agents in this receptor family are α2-agonists (e.g., brimonidine), which act in the opposite pharmacological direction. Primary hereditary glaucoma is also driven by specific genetic mechanisms (e.g., MYOC, CYP1B1 mutations), which have no established direct connection to adrenergic signaling.
A second, related candidate — open-angle glaucoma (TxGNN score 99.48%, rank 8696) — was also flagged by the model, but likewise has zero clinical trials or literature support. Both predictions currently rest solely on knowledge-graph link scores rather than experimental or clinical validation, and the drug’s known systemic effects (postural hypotension, tachycardia) raise additional feasibility questions for any ophthalmic application, for which no topical/ocular formulation data exist.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
Currently no related literature available.
Safety Considerations
- Drug Interactions: 32 interactions identified in total (DDInter), all classified as Moderate severity. Notable interacting agents include: Bupropion, Morphine, Canagliflozin, Dapagliflozin, Dronabinol, Empagliflozin, Nabilone, Ertugliflozin, Opium, Amifostine, Promethazine, Nitrous acid, Iobenguane (I-123), Epoprostenol, Iloprost, Selexipag, Treprostinil, Codeine, Hydrocodone, and Mepyramine.
(Key warnings and contraindications are not yet available — see Data Gap DG001 below.)
Conclusion and Next Steps
Decision: Hold
Rationale: The prediction is supported only by a TxGNN knowledge-graph score (Evidence Level L5) with zero clinical trials and zero literature, and the drug is not currently marketed in India (0 registrations). Combined with a Blocking-severity data gap on TFDA/local label safety information (DG001), there is insufficient evidence to advance this candidate past initial screening.
To proceed, the following is needed:
- TFDA label warnings/contraindications (DG001 — Blocking; required before any S1 safety screening can occur)
- Confirmed mechanism of action and original approved indication documentation (DG002)
- Preclinical or early clinical data testing IOP-lowering effect specifically (topical or systemic)
- Ophthalmic formulation and local safety/tolerability assessment, given known systemic hypotensive effects
- At minimum, one observational study or mechanistic study to move evidence level beyond L5
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.