Rimegepant

Limits on what this shows

• Key negative/null findings: The study authors explicitly caution that a compound's having a fitted parameter for a mechanism "should not be taken as proof that the mechanism is a potential liability for the compound," since the parameter "may not be active at the predicted liver concentration range." Run at a clinical dosing scenario of 75 mg once daily, more frequent than rimegepant's actual labeled every-other-day preventive interval and far more frequent than as-needed acute use, the integrated DILIsym model predicted only a 0.35 to 1% risk of meaningful ALT elevation for rimegepant, against 17.5 to 76.1% for telcagepant at its clinical dose. No hepatotoxicity or mitochondrial-injury signal has been reported in rimegepant's FDA label or in the sections of pivotal-trial safety reporting reviewed for this dossier.
• At-risk subgroups: None established at approved clinical dosing; this is a preclinical, mechanistic-tier signal only, modeled at an exposure frequency (once daily) more conservative than rimegepant's actual labeled dosing. Severe hepatic impairment already carries a labeled reduced-exposure caution for unrelated pharmacokinetic-clearance reasons (see PK basis); whether it would compound this in vitro signal is not established.

Regulatory status

Not addressed in the FDA label as a mitochondrial-toxicity finding; no hepatotoxicity warning or boxed warning appears in the sections of the label reviewed for this dossier.

Population evidence

Tier B. In vitro study, HepG2 human hepatocyte cell line, rimegepant named and tested directly alongside ubrogepant, atogepant, zavegepant, and the withdrawn first-generation gepant telcagepant. Oxygen consumption rate versus intracellular rimegepant concentration, measured by LC/MS/MS after 24-hour incubation, was fit with MITOsym modeling software, yielding electron-transport-chain inhibition parameters (reported inhibition constants of 1.89 µM and 3470 µM, maximum fractional inhibitory effect 0.45). Woodhead JL, Siler SQ, Howell BA, Watkins PB, Conway C. Comparing the Liver Safety Profiles of 4 Next-Generation CGRP Receptor Antagonists to the Hepatotoxic CGRP Inhibitor Telcagepant Using Quantitative Systems Toxicology Modeling. Toxicological Sciences. 2022;188(1):108-116. PMID 35556143, DOI 10.1093/toxsci/kfac051.

Mechanism

Named: electron transport chain inhibition in hepatocytes, detected via oxygen-consumption-rate modeling at the in vitro concentrations tested. The study's own integrated model attributed rimegepant's rare predicted ALT elevations to "ETC inhibition alone, with only mild contributions from bile acid transporter inhibition and ROS generation," making this the dominant of the three liver-toxicity mechanisms screened for rimegepant specifically. Not established as an active mechanism at the concentrations rimegepant actually reaches in the liver at approved dosing; see counter-evidence and framing caution.

Counter-evidence held on record

This is a supratherapeutic in vitro liver-toxicology screening result, generated specifically to compare next-generation gepants against the hepatotoxic telcagepant, not a demonstrated clinical mitochondrial-injury or nutrient-depletion effect. Do not present as an established human mitochondrial-toxicity risk. No mitochondrial-support supplementation (coenzyme Q10, carnitine, alpha-lipoic acid, or similar) is indicated on this basis. Separately, migraine itself, independent of any drug including rimegepant, has its own literature associating the disease with impaired brain energy metabolism, the rationale for riboflavin and coenzyme Q10 as migraine-prevention nutraceuticals (Tepper ST, Tepper KR. Nutraceuticals and Headache 2024: Riboflavin, Coenzyme Q10, Feverfew, Magnesium, Melatonin, and Butterbur. Curr Pain Headache Rep. 2025. PMID 39853578). That disease-level association is not evidence that rimegepant itself causes or worsens mitochondrial dysfunction, and the two should never be conflated on a consumer-facing page.

Limits on what this shows

• Key negative/null findings: The same concentration-relevance caveat from Mitochondrial burden applies, and the same DILIsym conclusion, that rimegepant carries a predicted 0.35 to 1% ALT-elevation risk at a once-daily clinical dosing scenario, well below telcagepant's 17.5 to 76.1%, applies here as well. A 2026 disease-level review (Szymanowicz O et al, Genes, PMID 42353782) frames oxidative stress in migraine as an open effect-versus-cause question at the level of the disease itself, not as a rimegepant drug effect; it is cited here purely to distinguish disease-level oxidative-stress research from any drug-specific claim, per Hard Rule 6, and does not add evidence for or against rimegepant.
• At-risk subgroups: None established clinically; preclinical screening signal only.

Regulatory status

Not addressed in the FDA label; no oxidative-stress-related adverse effect appears in the sections of the label reviewed for this dossier.

Population evidence

Tier B, same source as Mitochondrial burden (Woodhead et al 2022, PMID 35556143, see Overlap map). Reactive oxygen species formation was assayed by dihydroethidium (DHE) fluorescence in HepG2 cells after 24-hour incubation with rimegepant (Figure 4B of the source), yielding a reported ROS-production rate-constant parameter of 3.5 × 10 -4 mL/nmol/h. Telcagepant, rimegepant, atogepant, and ubrogepant all showed increased ROS in this assay; zavegepant, tested at a top concentration reported as substantially higher than the others, did not.

Mechanism

Named at the in vitro level: direct compound-driven reactive-oxygen-species induction in hepatocytes at the concentrations assayed, contributing a "mild" share (per the study's own attribution) to rimegepant's overall predicted liver-injury risk alongside the dominant electron-transport-chain-inhibition mechanism. This is a direct chemical/cytotoxic effect of the compound, distinct from, and not to be confused with, a separate and much more speculative mechanism: because the endogenous CGRP peptide itself has shown protective, antioxidant signaling in unrelated in vitro neuronal models (Schwann cells: Wu YL et al, Neurosci Lett, 2015, PMID 25960317; dorsal root ganglion cells: Liu YD et al, Oxid Med Cell Longev, 2019, PMID 31885775), CGRP-receptor blockade carries a theoretical, entirely unstudied possibility of blunting that endogenous protective pathway elsewhere in the body. No study of any gepant, rimegepant included, has tested this receptor-blockade hypothesis; it is disclosed here as background only and is not used to support this grade.

Counter-evidence held on record

Preclinical and mechanistic only, from a toxicology-screening assay, not a demonstrated clinical oxidative-stress or antioxidant-depletion problem at approved dosing. No antioxidant supplementation is indicated on this basis. This entry shares its evidence base with Mitochondrial burden and, more cautiously, ATP production (see Overlap map); treat the three as one preclinical dataset viewed from three required-category angles, not three independent confirmations. The separate CGRP-peptide antioxidant literature mentioned above is unstudied, theoretical, and must never be presented as an established receptor-blockade risk.

Limits on what this shows

• Why no grade: Both Step 7 conditions remain met after this session's re-attempt: no Tier B or C evidence and no circulating claim. Assessment: a genuine gap, reinforced rather than merely repeated, since the Crossref bibliographic listing this session provides a near-complete view of rimegepant's indexed literature (27 works) and none address copper, which is stronger evidence of absence than a single blocked query would be. A real tooling-limited component remains layered on top (Europe PMC, OpenAlex search, Semantic Scholar, eutils, and web search all unavailable this session). Mechanistically, rimegepant's absorption is not documented as chelation- or transporter-competition-mediated with respect to divalent cations, and its dominant elimination pathway is biliary/fecal excretion of unchanged parent drug plus CYP3A4/2C9 metabolism, not a copper-dependent enzymatic or transport pathway, which further reduces prior plausibility for this category.

Channels tried

FDA prescribing information (no copper-related interaction, absorption, or transporter mechanism documented); PubMed search-listing page, query "rimegepant copper" (PubMed silently substituted the truncated term "megepant," returning approximately 188,000 unrelated general-copper results, none rimegepant-specific, a search-engine artifact rather than a completed query); Crossref API, bibliographic query "rimegepant" returning all 27 works currently indexed under that term (case reports, pharmacokinetic modeling, regulatory summaries, trial and post-marketing safety reports), none titled or evidently concerning copper, ceruloplasmin, or trace-mineral status; a further Crossref query pairing "CGRP receptor antagonist" with copper/iron/trace-mineral terms returned an HTTP 429 before completing.

Channels blocked

Europe PMC's REST API returned a proxy-level HTTP 429 explicitly marked "do not fetch this page again" on the first attempt this session and was not retried per that instruction. The OpenAlex works-search endpoint (filter and full-text search modes) returned HTTP 429 on every attempt, though its per-DOI single-record lookup endpoint remained usable for records whose DOI was already known, none of which touch copper. The Semantic Scholar API returned HTTP 429. NCBI's eutils esearch endpoint (an alternative PubMed access route tried this session) was blocked outright by robots.txt. The built-in web-search tool returned no results because this session's web-search budget was already exhausted by earlier work in this batch, a session-level limit rather than a copper-specific finding. This matches the organization-level access pattern already disclosed for this drug and should not be read as a newly narrower search.

Circulating claim

None found; see Fails verification for the consumer-site check (drugs.com).

Limits on what this shows

• Why no grade: No Tier B or C evidence and no circulating claim. Assessment: a genuine gap, reinforced this session by the Crossref bibliographic listing and by the absence of any hematologic mention in the two rimegepant-specific safety sources newly located for Oxygen delivery/utilization, with a tooling-limited component still layered on top. Rimegepant's renal elimination is a minor pathway (24% of total recovered radioactivity, mostly as unchanged drug), and no tubular or absorptive mechanism plausibly touching iron status is documented in the label sections reviewed.

Channels tried

FDA prescribing information (no iron-related interaction, absorption effect, or renal-wasting mechanism documented); the Crossref bibliographic query described under Copper, covering all 27 works currently indexed for "rimegepant" (none titled or evidently concerning iron, ferritin, or transferrin status); the rimegepant-specific post-authorization safety abstract and the discontinuation/adverse-event comparison located this session for Oxygen delivery/utilization were checked directly for hemoglobin, anemia, or hematocrit mentions and contained none, cross-referenced from that entry.

Channels blocked

Same as Copper: Europe PMC blocked with an explicit do-not-retry instruction after the first attempt; the OpenAlex works-search endpoint, the Semantic Scholar API, and NCBI's eutils route were all unreachable (HTTP 429 or robots.txt) this session; the built-in web-search tool had no remaining budget in this session.

Circulating claim

None found; see Fails verification.

Limits on what this shows

• Why no grade: No Tier B or C evidence for the antagonist drug on gut-microbiome composition specifically, and no circulating claim. Assessment: a genuine gap, reinforced this session. The telcagepant transit-time abstract is a real class-member lead but tests a different endpoint (motility, not microbial composition or diversity) and could not be verified in full text, so per the Yellow-vs-white and Tier C standards it does not clear the bar for even a yellow grade on this specific category. The peptide/neuron-biology literature located establishes that endogenous CGRP signaling participates in gut immune and, in at least one non-CGRP-drug rat model, microbial regulation, a real and interesting mechanistic backdrop, but Tier B and C both require that a drug, this one or a class member, actually be tested on the microbiome-composition endpoint; none of the papers located do. Oral disintegrating tablets do transit the gastrointestinal tract, and rimegepant is a chronic, every-other-day exposure in its preventive indication, which keeps this category worth re-checking on a future revision, particularly if the telcagepant transit-time study's full text or a rimegepant-specific microbiome study becomes accessible.

Channels tried

The Crossref bibliographic listing of all 27 indexed rimegepant works (described under Copper) contains no gut-microbiome-related title; a further Crossref query pairing "CGRP receptor antagonist" with gut microbiome/microbiota terms returned no drug-specific match, surfacing only unrelated general microbiome literature plus one relevant lead: Johnson K, Li X, Li B. Characterization of Transit Times in the Large Intestine of Mice Following Treatment with a CGRP Antibody, CGRP Receptor Antibody and a Small Molecule CGRP Receptor Antagonist. Neurology. 2020;94(15 Suppl):1791 (abstract). DOI 10.1212/wnl.94.15_supplement.1791. Retrieved via OpenAlex per-DOI lookup, the abstract confirms the small-molecule antagonist tested was telcagepant, not rimegepant, and the endpoint was intestinal transit time in mice, not microbiome composition or diversity; no quantitative result could be retrieved from the available metadata (full text was not accessible this session). This is Tier C at best for rimegepant (class member tested, drug itself absent) and, even taken at face value, addresses a different Step 2 mechanism (altered transit time, mechanism class A) than the Step 3 gut-microbiome-composition category, so it is disclosed as background only and does not move the grade. Earlier in this same session, a broader query "CGRP gut microbiota intestinal" again surfaced basic-science literature on the endogenous CGRP peptide and gut-innervating sensory neurons modulating intestinal immune cell populations and, in one unrelated rat model, gut microbiota composition, with no gepant or other CGRP-receptor-antagonist drug appearing in any paper returned; representative citation: Xu H, Ding J, Porter CBM, et al. Transcriptional Atlas of Intestinal Immune Cells Reveals that Neuropeptide α-CGRP Modulates Group 2 Innate Lymphoid Cell Responses. Immunity. 2019. PMID 31618654.

Channels blocked

Europe PMC blocked with an explicit do-not-retry instruction; the OpenAlex works-search endpoint, the Semantic Scholar API, and NCBI's eutils route were all unreachable (HTTP 429 or robots.txt) this session; the built-in web-search tool had no remaining budget.

Circulating claim

None found; see Fails verification.

Limits on what this shows

• Key negative/null findings: Same as Mitochondrial burden: the authors' concentration-relevance caveat and the DILIsym model's low predicted clinical liver-injury risk for rimegepant (0.35 to 1% at a once-daily scenario) both argue against a clinically meaningful energy-metabolism effect at approved dosing, acute or preventive.
• At-risk subgroups: None established clinically.

Regulatory status

Not addressed in the label.

Population evidence

Same Woodhead et al 2022 source as Mitochondrial burden and Oxidative stress (PMID 35556143, DOI 10.1093/toxsci/kfac051, see Overlap map). The oxygen-consumption-rate assay used to detect electron transport chain inhibition is mechanistically linked to oxidative-phosphorylation capacity, but the study reports electron transport chain inhibition and, separately, ROS production as its measured endpoints, not a directly measured cellular ATP concentration or ATP-synthesis rate.

Mechanism

Inferred, not directly measured: electron transport chain inhibition mechanistically implies reduced oxidative-phosphorylation capacity and therefore reduced maximal ATP-synthesis capacity, at the in vitro concentrations tested. Not demonstrated as a clinical energy-metabolism deficit, and no rimegepant study measuring ATP directly was located through any channel tried.

Counter-evidence held on record

Graded yellow because a Tier B source touches this category, per protocol, but the underlying evidence is the same in vitro hepatocyte dataset already described under Mitochondrial burden and Oxidative stress (see Overlap map); treat all three entries as one preclinical finding viewed from three required-category angles, not three independent confirmations. No energy-support supplementation (coenzyme Q10, carnitine, creatine, or similar) is indicated on this basis.

Limits on what this shows

• Key negative/null findings: The post-authorization safety analysis is itself the key null finding: "no new safety signals associated with rimegepant treatment" across roughly 340,000 combined patient/patient-year exposure, with an ongoing Post Authorization Safety Study ("PASS") continuing to monitor. A separate rimegepant-specific matching-adjusted indirect comparison against zolmitriptan (12-month discontinuation and adverse-event analysis using individual patient data from trial NCT03266588; DOI 10.1136/jnnp-2025-abn.159) reported reduced rates of dizziness, somnolence, paresthesia, nausea, and asthenia for rimegepant, with no anemia, hemoglobin, or cardiovascular finding of any kind mentioned in the retrievable abstract. The earlier telcagepant coronary-artery study found no vasoconstriction. Rimegepant's elimination half-life of about 11 hours combined with its acute, as-needed dosing option and its every-other-day (not daily) preventive interval both limit sustained systemic CGRP-receptor blockade compared with a chronic daily medication.
• At-risk subgroups: Patients with underlying ischemic or vasospastic coronary or cerebrovascular disease represent a theoretical class-level concern per the mechanism above; neither rimegepant's label nor the post-authorization safety data single out this subgroup with a specific signal.

Regulatory status

The FDA label documents no cardiovascular warning, no blood-pressure precaution, and no vasospastic-disease contraindication for rimegepant.

Population evidence

Two tiers of evidence, re-verified this session. Tier B, class-level, established pharmacology, not rimegepant-specific: CGRP is a potent physiological vasodilator, and CGRP-receptor blockade is mechanistically capable of blunting a protective vasodilatory response during ischemia; this is the same class mechanism carried in this series' ubrogepant dossier, itself resting on a human isolated coronary artery study of telcagepant, an earlier-generation gepant, not rimegepant (Chan KY et al, J Pharmacol Exp Ther, 2010), which found no coronary vasoconstriction. Newly located this session, and rimegepant-specific: Chan A, Fournaire RJ, Pawinski R, Pixton G, Straghan E. Cardiovascular and cerebrovascular events during treatment of migraine with rimegepant, analysis of post-authorization safety data. J Neurol Neurosurg Psychiatry. 2025;96(Suppl 3), ABN Annual Meeting abstract, DOI 10.1136/jnnp-2025-abn.155. This Pfizer-authored post-marketing pharmacovigilance analysis covered periodic safety update reports from February 2022 through February 2024, with exposure estimated at 305,632 patients in the first reporting interval and 35,999 patient-years by the fourth interval; MedDRA-coded, Standardized-MedDRA-Query-categorized adverse event reports identified 78 cardiovascular and cerebrovascular events over the two-year period, with incidence reported as remaining stable and very low across intervals. This is a conference-abstract-level real-world safety surveillance source, not a peer-reviewed comparative trial, and is graded Tier B on that basis rather than Tier A.

Mechanism

Named at the class level only: CGRP-receptor antagonism blocking a vasodilatory rescue pathway during ischemia. Not confirmed as an active clinical mechanism for rimegepant; the post-authorization data above argue against it manifesting at a detectable population level. This is a mechanism and surveillance consideration, not a nutrient-mediated oxygen-delivery deficiency, and must not be filed as one (Hard Rule 2).

Counter-evidence held on record

This is the drug class's own pharmacologic action on CGRP signaling, described here as a theoretical mechanism reassured by real-world surveillance, not a demonstrated rimegepant-specific cardiovascular event, and not anemia or any other nutrient-mediated oxygen-delivery deficiency. No iron, B12, or other hematologic supplementation is indicated by this finding. Any cardiovascular concern belongs with the prescriber, not with a nutrient intervention. The post-authorization safety source is a conference abstract without an accessible full-text manuscript this session; its reported figures should be treated as provisional pending the underlying PASS publication.