Orphenadrine
| Evidence Level: L5 | Predicted Indications: 7 |
Table of Contents
Orphenadrine: From Parkinson Disease to Retinal Dystrophy
One-Sentence Summary
Orphenadrine is an anticholinergic drug originally used for parkinsonian disorders and Parkinson disease. The TxGNN model’s top-ranked prediction is retinal dystrophy with or without extraocular anomalies, but there are 0 clinical trials and 0 publications supporting it. Among the other predictions, only schizophrenia has a body of literature (16 publications), and these mostly concern managing antipsychotic side effects rather than treating the disease itself.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Parkinsonian disorder / Parkinson disease |
| Predicted New Indication | Retinal dystrophy with or without extraocular anomalies |
| TxGNN Prediction Score | 99.29% |
| Evidence Level | L5 |
| US Market Status | Cancelled only (all 5 licences cancelled) |
| Number of NDAs | 5 (all ANDAs, all cancelled) |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Detailed mechanism-of-action data is not available in the data compiled for this report. From general pharmacology, orphenadrine is an anticholinergic agent with NMDA-channel-blocking and antihistamine activity. Its efficacy in parkinsonism comes from central muscarinic blockade.
For the top-ranked prediction, retinal dystrophy, no mechanistic link can be identified. None of orphenadrine’s known actions connects to inherited retinal degeneration. Despite the high score (0.993), the prediction is most likely a knowledge-graph artifact.
The other genetic or developmental predictions are also unsupported:
- Congenital disorder of glycosylation (defective fucosylation): a glycan-synthesis defect that muscarinic, NMDA or H1 pharmacology does not address.
- Perisylvian polymicrogyria with cerebellar hypoplasia and arthrogryposis: a genetic brain malformation that a symptomatic anticholinergic cannot be expected to alter.
- Charcot-Marie-Tooth disease type 1G: a hereditary demyelinating neuropathy with no known disease-modifying effect from orphenadrine.
- X-linked myopia and myopia 26 (X-linked, female-limited): antimuscarinic action is loosely relevant to myopia control (as with atropine), but orphenadrine is a systemic agent with no ophthalmic data, and these are genetic conditions.
Schizophrenia (rank 5, score 99.13%, evidence level L3) is the only prediction with literature support. Orphenadrine is used as an adjunct to manage antipsychotic-induced extrapyramidal symptoms. Its NMDA-blocking activity is pharmacologically interesting given the glutamatergic hypothesis of schizophrenia. However, NMDA antagonists tend to cause psychotomimetic effects, and anticholinergics can worsen cognition and tardive dyskinesia. The literature supports treating side effects, not the core disease.
Clinical Trial Evidence
Currently no related clinical trials are registered for the top-ranked prediction (retinal dystrophy) or for any other predicted indication.
Literature Evidence
Currently no related literature is available for retinal dystrophy. For reference, the literature below concerns the schizophrenia prediction (rank 5):
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 29341071 | 2018 | Review | Cochrane Database Syst Rev | Anticholinergic medication for antipsychotic-induced tardive dyskinesia; animal data suggest chronic anticholinergics might themselves cause tardive dyskinesia |
| 10796321 | 2000 | Review | Cochrane Database Syst Rev | Earlier review of anticholinergics for neuroleptic-induced tardive dyskinesia |
| 4571143 | 1972 | RCT | Psychol Med | Amantadine vs orphenadrine vs placebo for phenothiazine-induced parkinsonism |
| 8369232 | 1993 | RCT | Schizophr Res | Placebo, orphenadrine and rising chlorpromazine doses on an attention task in chronic schizophrenia (two-year study) |
| 3698889 | 1986 | Clinical study | L’Encephale | In 22 schizophrenic patients on haloperidol, orphenadrine significantly reduced extrapyramidal symptoms, and withdrawal led to marked deterioration |
| 2616635 | 1989 | Naturalistic study | Pharmacopsychiatry | 44 schizophrenic outpatients on haloperidol plus orphenadrine assessed for residual parkinsonian, depressive and anticholinergic symptoms |
| 324238 | 1977 | Clinical study | Acta Psychiatr Scand | In 118 patients on long-term neuroleptics, need for antiparkinsonian drugs depended on neuroleptic potency |
| 12459931 | 2003 | Preclinical | Psychopharmacology | Low-affinity NMDA channel blockers and disruption of prepulse inhibition in rats |
All of these concern side-effect management or pharmacology, not treatment of schizophrenia itself.
US Market Information
All five US authorisations are generic applications (ANDAs) and all are cancelled. No approved indication text is available.
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| ANDA090585 | Orphenadrine Citrate (Sagent Pharmaceuticals) | Injection, solution | Not available (cancelled) |
| ANDA040284 | Orphenadrine Citrate (A-S Medication Solutions) | Tablet, extended release | Not available (cancelled) |
| ANDA040327 | Orphenadrine Citrate (Proficient Rx LP) | Tablet, extended release | Not available (cancelled) |
| ANDA040463 | Orphenadrine Citrate (Hikma Pharmaceuticals USA Inc.) | Injection | Not available (cancelled) |
| ANDA084779 | Orphenadrine Citrate (Actavis Pharma, Inc.) | Injection | Not available (cancelled) |
Safety Considerations
Package insert warnings and contraindications were not available in the data compiled for this report. Please refer to the package insert.
- Contraindicated conditions (knowledge-graph data, not label text): Associations are listed for hypertension, liver failure and liver disease, kidney disease and impaired renal function, epilepsy, insomnia, gallbladder disease, peptic ulcer disease, benign prostatic hyperplasia, gout, substance abuse/dependence, thrombocytopenia, hemophilia, anaemia (including macrocytic), sudden cardiac arrest, heart conduction disease, myasthenia gravis and other neuromuscular junction disease, paracetamol poisoning, achalasia and megaesophagus, glaucoma, pyloric stenosis, bladder neck obstruction and pyoureter.
- Drug interactions: 100 interactions were found. The ones identified as Major are:
- Morphine (including liposomal morphine)
- Potassium citrate
- Potassium chloride
Many Moderate interactions involve other anticholinergic or antimuscarinic drugs, including hyoscyamine, atropine, glycopyrronium, dicyclomine, clidinium, mepenzolate, methscopolamine and propantheline. Others are loperamide, bupropion, dronabinol, nabilone, eluxadoline, metoclopramide and opium.
Conclusion and Next Steps
Decision: Hold
Rationale: The top-ranked prediction, retinal dystrophy, has a high model score but no clinical trials, no literature and no identifiable mechanistic link, so it is most likely a knowledge-graph artifact. The same is true of the other genetic and developmental predictions. Schizophrenia is the only prediction with literature, but that evidence covers side-effect management rather than disease treatment, and it warrants only a research question. In addition, all US licences are cancelled and safety label data are missing.
To proceed, the following is needed:
- FDA package insert warnings and contraindications (a blocking gap for safety screening)
- Mechanism-of-action data from DrugBank
- A defined mechanistic hypothesis and preclinical evidence for any genetic or ocular indication before further investment
- For schizophrenia, evidence that orphenadrine affects the core disease and not only extrapyramidal side effects, weighed against the risks of cognitive worsening and tardive dyskinesia
- Clarification of the commercial and regulatory pathway, since no US licence is currently active
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.