Brexpiprazole

Limits on what this shows

• Null/negative findings: The authors note tested concentrations (5 to 10 micromolar) substantially exceed typical clinical plasma exposure (0.2 to 0.5 micromolar), though they flag a possible up to nine-fold brain accumulation reported for related compounds in rodent models as a reason the true in vivo brain concentration is uncertain. No human clinical mitochondrial-function study in brexpiprazole-treated patients was located.
• At-risk subgroups: Not established in humans; theoretical only, and the strongest effect in this study was in midbrain dopaminergic neurons specifically, not a generalized tissue effect.

Regulatory status

Not addressed in the FDA label.

Population evidence

Pryde KR et al., Biology Direct 2023 (DOI 10.1186/s13062-023-00375-9): a multi-model laboratory investigation across human SH-SY5Y neuroblastoma cells, primary embryonic mouse forebrain and ventral midbrain neurons, human cardiomyocytes, isolated bovine mitochondrial membranes and complex I, and Drosophila melanogaster cells and whole organisms. Brexpiprazole reduced oxygen consumption rates in SH-SY5Y cells and produced dose-dependent reductions in NADH oxidation by isolated mitochondrial membranes at concentrations of 5 micromolar and above, acting selectively at the ubiquinone-binding (Q) site rather than the flavin site, described by the authors as a "cork in a bottle" mechanism. Chronic Drosophila exposure produced mitochondrial ultrastructural damage and locomotor dysfunction in vivo.

Mechanism

Direct, off-target physical blockade of the ubiquinone-binding Q-channel of complex I, independent of brexpiprazole's dopamine/serotonin receptor pharmacology. Ventral midbrain neurons showed greater bioenergetic inhibition than forebrain neurons in this study.

Counter-evidence held on record

The tested concentration range is well above standard therapeutic plasma exposure, and no clinical correlate (fatigue, exercise capacity, a measured mitochondrial marker) has been studied in brexpiprazole-treated patients. This entry shares its primary source with ATP production and with the coenzyme Q10 entry below; see Overlap map. Do not interpret this entry as support for mitochondrial-support supplementation such as coenzyme Q10 in patients on standard therapeutic brexpiprazole dosing; no clinical trial evidence supports this, and the mechanism described is site-blockade, not a nutrient deficiency.

Limits on what this shows

• Null/negative findings: Not established; the null/negative-findings search for this specific paper could not be completed given the access limitation above. No other brexpiprazole-specific human or animal oxidative-stress study was located; a PubMed search for "brexpiprazole oxidative stress" returned only this record and one unrelated analytical-chemistry degradation study (PMID 36226712, not a biological oxidative-stress finding).
• At-risk subgroups: Not established; cardiotoxicity outcome, animal model, long-term exposure only as far as could be confirmed.

Regulatory status

Not addressed in the FDA label. The label documents cardiovascular findings limited to orthostatic hypotension and syncope risk, with no QTc prolongation signal at up to four times the maximum recommended dose; no oxidative-stress-mediated cardiotoxicity is described.

Population evidence

Alissa M et al., "Brexpiprazole induces acute cardiotoxicity via disrupting calcineurin/NFAT and calcium signaling pathway: A validation from biochemical, echocardiographic, histological, and computational analysis," PMID 41579687, 2026. The title and an initial search snippet indicate the study used biochemical, echocardiographic, histological, and computational methods, consistent with a rodent in vivo cardiotoxicity protocol, and that "long-term exposure to BPZ results in cardiotoxicity mediated by oxidative" mechanisms. Species, dose, exact oxidative markers (glutathione, malondialdehyde, superoxide dismutase, or catalase), and effect magnitudes could not be confirmed: repeated attempts to open the PubMed abstract page, and to reach Semantic Scholar, Europe PMC, Crossref, and OpenAlex for the same record, all returned HTTP 429 rate-limit responses during this review.

Mechanism

Title-level only: calcineurin/NFAT and calcium-signaling disruption is named as the proposed pathway, with oxidative stress described as a mediating mechanism for the cardiotoxicity outcome. The specific redox markers and their direction of change could not be confirmed from the sources reachable during this review.

Counter-evidence held on record

None identified; this entry could not be counter-evidenced because the underlying source could not be fully read during this review. The human label's own cardiovascular safety data (orthostatic hypotension and syncope, no QTc signal at high multiples of dose) come from randomized controlled trials, a stronger evidence class than a single animal cardiotoxicity report, and should be weighed accordingly by a reader. This is a disclosed partial finding, not a confirmed clinical cardiotoxicity or antioxidant-depletion signal. Do not treat this entry as support for antioxidant supplementation in patients on brexpiprazole. A future revision of this dossier should re-attempt full-text retrieval of PMID 41579687 once the channels above are no longer rate-limited.

Limits on what this shows

• Null/negative findings: Risperidone, the third drug studied in the same cohort, has a different receptor profile (full D2 antagonism) and did not show the same copper decrease, arguing against a blanket antipsychotic-class effect and against assuming the finding automatically transfers to every partial agonist. No brexpiprazole-specific copper study, positive or null, exists to confirm or refute the extrapolation.
• At-risk subgroups: Not established for brexpiprazole. By class analogy only, longer-treated patients might be the plausible highest-risk group, though the source study's mean follow-up was under 4 weeks, too short to establish a long-term risk profile even for aripiprazole.

Regulatory status

Not addressed in the FDA label; copper is not mentioned in the label sections reviewed for brexpiprazole.

Population evidence

Chen X, Li Y, Zhang T, Yao Y, Shen C, Xue Y. Biol Trace Elem Res. 2017 (PMID 28470477, DOI 10.1007/s12011-017-1039-6): case-control study of 165 schizophrenia inpatients versus 614 healthy controls measured serum magnesium, copper, calcium, phosphorus, iron, and zinc, then followed the patient group prospectively (mean 3.8 weeks) through treatment with risperidone, clozapine, or aripiprazole using repeated-measures ANOVA. Serum copper was significantly decreased after clozapine and aripiprazole treatment specifically (P<0.05), reported jointly rather than as two separately quantified effect sizes. Brexpiprazole was not approved until 2015 and was not part of this cohort. A fresh Europe PMC search during this review ("brexpiprazole" combined with copper/trace-element terms, 175 results) and a fresh PubMed search-listing query found no brexpiprazole-specific copper result of any kind.

Mechanism

Not established by the study authors for aripiprazole, and no mechanism has been proposed or tested for brexpiprazole. The extrapolation rests on shared receptor pharmacology (both D2/5-HT1A partial agonists with 5-HT2A antagonism, from the same Otsuka development lineage), not a demonstrated shared biochemical pathway.

Counter-evidence held on record

This is Tier C by definition: brexpiprazole was absent from the only study showing this effect, and the mechanism is unestablished even in the drug where it was observed. Per Hard Rule 6, confounding by indication and by class-drug substitution is presumed until excluded, and it is not excluded here. Do not supplement copper based on this entry. The direction of the aripiprazole finding is a decrease, and if it extrapolates to brexpiprazole at all, empiric copper supplementation without a measured low serum copper level would be inappropriate, given copper's narrow safety margin and its interaction with zinc status.

Limits on what this shows

• Null/negative findings: The same meta-analysis found a weaker, less consistent ferritin signal than the serum-iron signal, and the underlying studies were cross-sectional, so reverse causation (akathisia-related reduced food intake lowering iron) cannot be excluded. No study measuring iron status specifically in brexpiprazole-treated patients was located; a fresh PubMed search for "brexpiprazole iron ferritin" during this review returned zero results.
• At-risk subgroups: Not established for brexpiprazole specifically. By class-level analogy, patients with baseline low-normal iron or ferritin, particularly in the adjunctive MDD indication where brexpiprazole's own akathisia incidence is highest (9% versus 2%).

Regulatory status

The FDA label does not mention iron or ferritin. Akathisia is a labeled adverse reaction: 9% versus 2% on placebo in adjunctive MDD trials, 6% versus 5% in adult schizophrenia trials, 4% versus 3% in pediatric schizophrenia trials (ages 13 to 17), and 1% versus 0% in dementia-related agitation trials, confirmed directly from the DailyMed SPL adverse-reactions tables during this review.

Population evidence

Schoretsanitis G, Nikolakopoulou A, Guinart D, Correll CU, Kane JM. Eur Neuropsychopharmacol. 2020;35:1-11 (DOI 10.1016/j.euroneuro.2020.04.001): systematic review and meta-analysis of 10 cross-sectional studies (n=395; 182 with akathisia, 213 without) found serum iron significantly lower in patients with akathisia (SMD -0.49, 95% CI -0.70 to -0.28, P<0.001, fixed-effect model); ferritin showed a weaker signal. Every included study predates brexpiprazole's 2015 approval and studied first-generation and early second-generation antipsychotics, not brexpiprazole.

Mechanism

The proposed mechanism (from the non-brexpiprazole literature) is that low brain iron impairs striatal D2 receptor function, lowering the threshold for extrapyramidal symptoms including akathisia. Brexpiprazole's own pharmacology (D2/5-HT1A partial agonism, 5-HT2A antagonism) is mechanistically distinct from the full D2 antagonists studied in the iron literature, and its own akathisia rate, while real, is markedly lower than aripiprazole's (8 to 25% across indications, per the aripiprazole dossier in this series) or cariprazine's (9 to 21%), making this extrapolation weaker for brexpiprazole than for those closer-by-rate class members.

Counter-evidence held on record

Under Hard Rule 6, confounding by indication and by class-drug substitution is presumed until excluded, and it is not excluded here: no brexpiprazole patient was in the iron/ferritin-measured cohort, and brexpiprazole's own akathisia incidence is real but comparatively modest next to other class members carrying the same extrapolated flag. This entry's only drug-specific fact, the akathisia rate, is a clinical outcome, not a nutrient measurement, cited as context per Hard Rule 2, not as iron evidence; see Overlap map. Do not supplement iron in a brexpiprazole-treated patient based on akathisia symptoms alone. Iron overload carries its own toxicity risk; any repletion should follow a lab-confirmed low ferritin or iron panel and be prescriber-directed, kept under the NIH Office of Dietary Supplements tolerable upper intake level for elemental iron (45 mg/day for adults from supplements). This dossier makes no standing dosing recommendation.

Limits on what this shows

• Null/negative findings: Cussotto et al. found the ileal-permeability change was not causally attributable to the microbiome shift, arguing against a simple composition-drives-permeability narrative even for aripiprazole. The direction of effect conflicts across the three aripiprazole studies themselves (diversity increased in two systems, beneficial phyla decreased in a third), so this is not a settled dysbiosis story even for the class member with real data. The original review's PubMed search for "brexpiprazole gut microbiome" (3 results, none on point) and a fresh Europe PMC cross-check during this follow-up pass located no brexpiprazole-specific primary study.
• At-risk subgroups: Not established for brexpiprazole. Brexpiprazole's own comparatively smaller weight-gain liability argues against, not for, a microbiome effect of similar magnitude to aripiprazole's, by the same weight-gain-linked mechanism documented for the more metabolically active atypicals elsewhere in this series.

Regulatory status

Not addressed in the FDA label.

Population evidence

Cussotto et al. 2019 (Psychopharmacology 236(5):1671-1685, DOI 10.1007/s00213-018-5006-5): chronic oral aripiprazole in rats significantly increased microbial species richness and diversity and specific genera (Clostridium, Peptoclostridium, Intestinibacter, Christensenellaceae) versus controls, alongside increased ileal permeability not causally linked to the composition change. Ait Chait et al. 2023 (Int J Mol Sci 24(8):7326, DOI 10.3390/ijms24087326): a 48-hour ex vivo human-colon fermentation model found aripiprazole decreased Firmicutes and Actinobacteria, increased Proteobacteria, reduced several beneficial families, and lowered butyrate, propionate, and acetate; a probiotic combination largely reversed these changes. Leão et al. 2025 (Microbiology Spectrum, DOI 10.1128/spectrum.02350-25): an in vitro colonic-fermentation model found aripiprazole increased microbial diversity in a female-derived model, with short-chain-fatty-acid changes not reaching statistical significance. None of these three studies included brexpiprazole.

Mechanism

Not resolved to a single named pathway in any of the three aripiprazole papers; proposed routes include direct antimicrobial or growth-modulating activity on specific taxa and a broader ecological shift following chronic systemic exposure. Whether brexpiprazole, sharing aripiprazole's D2/5-HT1A partial-agonist, 5-HT2A-antagonist profile but with a materially smaller weight-gain liability (mean 1.3 to 1.6 kg at 6 weeks in MDD adjunctive use per brexpiprazole's own label, versus aripiprazole's larger metabolic footprint), would produce a microbiome shift of similar magnitude is untested.

Counter-evidence held on record

Brexpiprazole's own comparatively favorable metabolic profile argues against the magnitude of microbiome disruption documented for aripiprazole, and more so for olanzapine and risperidone, applying to brexpiprazole with equal force. This is class extrapolation from a pharmacologically similar but metabolically distinct relative, not brexpiprazole-specific evidence. No probiotic strain or dose has clinical trial support for brexpiprazole-treated patients. Do not substitute probiotic supplementation for standard metabolic monitoring (weight, glucose, lipids per the label).

Limits on what this shows

• Null/negative findings: No in vivo human clinical energy-metabolism study (fatigue scales, lactate, exercise testing) in brexpiprazole-treated patients was located.
• At-risk subgroups: Not established; the finding comes from an in vitro exposure range, not chronic therapeutic human dosing.

Regulatory status

Not addressed in the FDA label.

Population evidence

Pryde KR et al., Biology Direct 2023 (DOI 10.1186/s13062-023-00375-9): ATP depletion was documented in galactose-cultured cells (a standard assay that forces cells to rely on oxidative phosphorylation rather than glycolysis) exposed to brexpiprazole at the same supratherapeutic concentration range used for the complex I findings above.

Mechanism

Downstream consequence of Q-site complex I blockade described above; this entry shares its underlying source with Mitochondrial burden, not counted as independent confirmation. See Overlap map.

Counter-evidence held on record

No clinical correlate has been studied in brexpiprazole-treated patients specifically, and the effective concentrations exceed typical plasma exposure. Does not support ATP-support supplementation, such as coenzyme Q10 or creatine, in patients on standard therapeutic brexpiprazole dosing.

Limits on what this shows

• Null/negative findings: Olanzapine, run as a comparator in the same experiment, did not produce the same haemolysis signal, arguing the aripiprazole effect is drug-specific within that experiment rather than a general antipsychotic or vehicle artifact; this cuts against, not for, assuming the effect generalizes to every class member including brexpiprazole. A fresh PubMed search for "brexpiprazole erythrocyte" during this review returned zero results.
• At-risk subgroups: Not established for brexpiprazole or aripiprazole; this is a fixed-concentration in vitro finding in healthy-donor blood, not a clinical population result for either drug.

Regulatory status

Not addressed in the FDA label; the label documents leukopenia, neutropenia, and agranulocytosis (white-cell, class-labeled effects), not red-cell or oxygen-delivery findings, tracked separately in the monitoring panel.

Population evidence

Pirc Marolt T, Kramar B, Vovk A, Podgornik H, Šuput D, Milisav I. Antioxidants (Basel). 2023;12(11) (PMID 38001783): residual blood from 25 healthy donors was obtained and aripiprazole added ex vivo at a 6 micromolar, therapeutic-range concentration for a 2-hour, 37-degree-C incubation. Destruction of approximately 1 percent of erythrocytes was detected "only in the presence of ARI" versus DMSO and olanzapine controls; the same study also found persistent mitochondrial hyperpolarization and moderate oxidative stress in liver cells at the same concentration. Brexpiprazole was not one of the drugs tested.

Mechanism

Not fully elucidated by the study authors for aripiprazole; proposed to relate to the same membrane/redox perturbation observed in the paired liver-cell experiments in the same paper. No brexpiprazole-specific mechanism has been proposed or tested; brexpiprazole shares aripiprazole's D2/5-HT1A partial-agonist and 5-HT2A-antagonist binding profile, but the two molecules differ in exact receptor affinities, and brexpiprazole's own documented off-target mitochondrial effect (Q-site complex I blockade, see Mitochondrial burden entry above) is a distinct mechanism from the membrane/redox perturbation proposed for aripiprazole's haemolysis finding, so a shared erythrocyte effect is plausible but unconfirmed and should not be read as the same finding twice.

Counter-evidence held on record

This entry rests entirely on a study that did not include brexpiprazole; the extrapolation is supported only by shared receptor pharmacology with aripiprazole. Brexpiprazole's own separately documented mitochondrial complex I interference (see Mitochondrial burden entry) is a different mechanism than the one proposed here for aripiprazole's haemolysis finding, and the two should not be read as confirming each other; see Overlap map. Roughly 1 percent in vitro haemolysis in aripiprazole-exposed donor blood is not evidence of clinical anemia in aripiprazole patients, let alone in brexpiprazole patients, where no comparable data exists at all, and must not be marketed as such. It must also not be conflated with brexpiprazole's separately labeled leukopenia/neutropenia/agranulocytosis warnings, which concern different blood-cell lineages.