Apomorphine

Evidence Level: L5

Predicted Indications: 10

Apomorphine

Pharmacist Assessment Report

Apomorphine: From Parkinson Disease to polymicrogyria, perisylvian, with cerebellar hypoplasia and arthrogryposis

One-Sentence Summary

Apomorphine is a dopamine agonist originally used to treat Parkinson disease and related parkinsonian syndromes. The top-ranked TxGNN prediction is a rare developmental malformation (polymicrogyria) with no supporting evidence, so this report focuses on the best-supported prediction, schizophrenia (rank 5). It is backed by no registered clinical trials and 19 publications, mostly older, small or indirect studies. Overall, the evidence is hypothesis-level, and the direction of any therapeutic effect is uncertain.

Quick Overview

Item	Content
Original Indication	Parkinson disease (the licence records contain no approved indication text)
Predicted New Indication	Top-ranked: polymicrogyria, perisylvian, with cerebellar hypoplasia and arthrogryposis (L5, no evidence). Best-supported: schizophrenia (rank 5)
TxGNN Prediction Score	0.9975 (rank 1); 0.9969 (schizophrenia)
Evidence Level	L5 for the rank 1 prediction; L3 for schizophrenia
India Market Status	Listed in a compiled Indian medicine price dataset (2 of 2) – CDSCO approval status is not included in this data
Number of Listed Products	2 (valid: 2)
Recommended Decision	Hold (rank 1 prediction); schizophrenia is a research question only

Why is This Prediction Reasonable?

Currently, detailed mechanism of action data is not available in the data compiled for this report. Based on known pharmacology, apomorphine is a dopamine D1/D2 receptor agonist. Its efficacy in Parkinson disease comes from replacing deficient dopaminergic signalling.

Rank 1 (polymicrogyria with cerebellar hypoplasia and arthrogryposis): No mechanistic link can be identified. The score is very high, but it appears to be a TxGNN model (deep learning) prediction only, and nothing connects dopaminergic signalling to the pathogenesis of this rare developmental malformation. The other top-ranked predictions have similarly weak or absent rationales. These include congenital glycosylation disorder, hereditary neuropathy, atypical glycine encephalopathy and hydranencephaly. The exceptions are retinal dystrophy and the myopia variants, where retinal dopamine offers only a speculative link.

Schizophrenia (rank 5): There is a clear pharmacological connection through the dopamine hypothesis. However, the direction is problematic. A D1/D2 agonist would be expected to worsen psychosis rather than treat it. The older literature mainly uses apomorphine as a probe of dopamine function. Small 1980s studies of low-dose apomorphine found no significant therapeutic improvement. The 1984 study of 25 patients showed no significant improvement or deterioration. A 1983 study of 12 chronic patients showed no overall difference from placebo, though anxiety and depression subscales improved.

Clinical Trial Evidence

Currently no related clinical trials registered.

Literature Evidence

Evidence for schizophrenia (10 of the 19 publications are summarised here, ordered by relevance; the study-type labels are based on titles and abstracts as compiled):

PMID	Year	Type	Journal	Key Findings
6372737	1984	Clinical study	Arch Gen Psychiatry	Low-dose apomorphine (0.75 mg SC) vs placebo in 25 male schizophrenics: no significant improvement or deterioration
6682989	1983	Double-blind study	Prog Neuropsychopharmacol Biol Psychiatry	12 chronic patients: no overall difference vs placebo; anxiety and depression subscales improved
6718635	1984	Clinical study (details not verified)	Psychopharmacol Bull	Apomorphine and schizophrenia (no abstract available)
11394190	2001	Review/Commentary	J Psychiatry Neurosci	Little evidence that apomorphine at postsynaptic doses induces or worsens psychosis, which challenges the dopamine hypothesis
1099172	1975	Double-blind study	J Neurol Neurosurg Psychiatry	40 men, mainly alcoholics: no endogenous depression or schizophrenic symptoms developed with apomorphine
540209	1979	Neuroendocrine study	Br J Psychiatry	Growth hormone and prolactin responses to apomorphine in schizophrenia research
12727131	2003	Clinical study	Psychoneuroendocrinology	Prolactin, ACTH and cortisol responses to apomorphine in 20 untreated schizophrenic inpatients vs 23 controls
30805732	2019	Review	J Neural Transm	Overview of classical dopamine agonists, including parenteral apomorphine in Parkinson disease
33571431	2021	Structural biology	Cell	Cryo-EM structures of D1 and D2 dopamine receptor signalling complexes
12405516	2002	Preclinical	Behav Genet	Apomorphine-susceptible and unsusceptible rat lines as models of psychopathology

The remaining publications are indirect (BPC 157 peptide work, clozapine and aripiprazole reviews, a plant-extract mouse study, and general reviews).

No literature was available for the other nine top-ranked predictions.

India Market Information

Authorization Number	Product Name	Dosage Form	Approved Indication
1655	Apotab 2 Sublingual tablet (Alteus Biogenics Pvt Ltd)	Strip of 10 sublingual tablets	Not stated in the data compiled
248265	Zyprima 3mg Tablet (Zydus Cadila)	Strip of 4 sublingual tablets	Not stated in the data compiled

Safety Considerations

Contraindication-related conditions (from the knowledge graph, not label text): multiple system atrophy, postural orthostatic tachycardia syndrome, orthostatic hypotension, drug-induced dyskinesia, long QT syndrome (including familial), torsades de pointes, liver disease, gallbladder disease, psychotic disorders (including schizophreniform and schizoaffective disorder), mental disorder, potassium deficiency, substance abuse/dependence, coronary artery disease, impaired renal function, priapism and cerebrovascular disorder.

Note that psychotic disorder appears on this list, which directly conflicts with the schizophrenia prediction.

Drug Interactions: 173 interactions were recorded. The main examples are:

Major: alosetron, cisapride, dolasetron, granisetron (consistent with QT-prolongation and serotonergic or gastrointestinal concerns)
Moderate: famotidine, loperamide, bupropion, clarithromycin, levofloxacin, metoclopramide, dronabinol, and several laxatives (bisacodyl, castor oil, lactulose, lactitol, magnesium salts, mineral oil, glycerin)
Minor: metronidazole

Please refer to the package insert for further safety information.

Conclusion and Next Steps

Decision: Hold

Rationale: The top-ranked prediction (polymicrogyria) has a very high model score but no trials, no literature and no plausible mechanism (evidence level L5). Schizophrenia has the most literature (evidence level L3). However, it is limited to small, early or indirect studies. Findings were largely negative or unclear, and psychotic disorder is a recorded contraindication. It is therefore a research question rather than a candidate for advancement.

To proceed, the following is needed:

Mechanism of action data from DrugBank
Package insert warnings and contraindications from the India Pharma sources (a blocking gap for safety screening)
Approved indication text for the two India registrations
Preclinical or mechanistic evidence for any rank 1 to 4 prediction before further consideration
For schizophrenia, a clear rationale for the therapeutic direction (agonist vs antagonist) and a risk assessment given the psychosis contraindication
Route compatibility assessment (the marketed forms are sublingual tablets)
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.