Dantrolene

Limits on what this shows

• Key null findings: No source measured mitochondrial membrane potential, respiration or mitochondrial DNA in dantrolene-treated people. A PubMed listing for dantrolene with mitochondrial membrane potential returned 10 records; the rat brain-injury paper [9] was the only one with dantrolene in the title, and the skeletal muscle ryanodine receptor paper [13] also appeared; the remaining records were unrelated mitochondrial or calcium papers seen by title only [16]. A Crossref title search surfaced a 2012 Biophysical Journal item titled "Dantrolene-Sensitive Mitochondrial Ca2+ Uptake under Mitochondrial Ca2+ Uniporter Inhibition" (title only, not opened, not graded) [17].
• At-risk subgroups: None established for mitochondrial burden. The label hepatotoxicity risk groups (females, age over 35 years, high daily doses) are drug-toxicity risk groups, not mitochondrial findings [1].

Direction

Mixed and model-dependent. Toxic-direction signal in human liver tissue ex vivo and in vitro [7][8]; protective direction in injured rat brain [9]; mechanistic reduction of RyR-routed mitochondrial calcium uptake in cardiomyocytes and muscle fibers [12][13]. None of these is a nutrient deficiency and none measured a nutrient (Hard Rule 2). Drug toxicity and intended-pharmacology context, not depletion.

Regulatory status

The three labels read describe no mitochondrial finding and make no mitochondrial statement in the sections returned [1][2][3]. The oral label boxed warning concerns hepatotoxicity without naming a mitochondrial mechanism [1].

Population evidence

No human in vivo study. Vickers et al. 2017 (Int J Mol Sci), ex vivo 3-dimensional human liver slices, eight drugs named in the abstract; it states "Drugs targeting mitochondria more than GSH were dantrolene (DTL, 10 µM) and cyclosporin A (CSA, 10 µM)", and a composite of stress and toxicity gene categories (including oxidative stress and mitochondrial energy genes) ranked dantrolene at 48% against 75% for cyclosporin A; the direction of the ATP change for dantrolene specifically, the donor number and the exposure time were not in the abstract text read [7]. Xu et al. 2008 (Toxicol Sci), more than 300 drugs in primary human hepatocyte cultures with mitochondrial damage, oxidative stress and glutathione read by high-content imaging; dantrolene is named in the abstract among human hepatotoxicants identified, with dantrolene-specific readouts not in the abstract [8]. Chakraborty et al. 2024 (Biochem Pharmacol), male Wistar rats after traumatic brain injury given dantrolene 10 mg/kg: reduced mitochondrial dysfunction and inhibition of mitochondria-mediated apoptosis (PubMed record as returned by a summarizing fetch tool; the full text was not opened) [9].

Mechanism

Named at the target level: dantrolene is a ryanodine receptor antagonist and in cardiomyocytes attenuated mitochondrial calcium uptake that was insensitive to the uniporter blocker Ru360 [12]. How this links to the human liver-slice signal is not established in any source read.

Counter-evidence held on record

Counter-evidence and limits All human-derived evidence is ex vivo or in vitro. The human liver-slice and hepatocyte panels flag dantrolene as a hepatotoxicant model compound, which is the label boxed warning stated in another way, not a new nutrient finding. The rat brain-injury result is in the opposite direction. Experimental concentrations (10 µM) and animal doses (10 mg/kg) are not clinical exposures and are not compared here with human plasma levels. Framing caution Do not present this as dantrolene "damaging mitochondria" or "draining cellular energy" in people, and do not suggest mitochondrial supplements. It is a laboratory signal of unknown clinical meaning.

Limits on what this shows

• Key null findings: No serum or tissue antioxidant capacity, urinary isoprostane, malondialdehyde or glutathione measurement in dantrolene-treated people was retrieved. A PubMed listing for dantrolene with oxidative stress and antioxidant returned 10 records; two had dantrolene in the title with an oxidative-stress outcome, the rat irradiation paper [10] and a 2019 rabbit bladder spinal cord injury paper (Keles, title only, not opened) [16]; neither was human.
• At-risk subgroups: None established.

Direction

Mixed. Reactive-metabolite and glutathione-conjugation signal (toxic direction) [11]; antioxidant signal in two rat models (reverse or protective direction) [9][10]. No human tissue redox marker was reported for dantrolene users. Not a nutrient deficiency; no antioxidant nutrient was measured.

Regulatory status

No label section read mentions oxidative stress, antioxidant status or glutathione [1][2][3].

Population evidence

Arnold et al. 1983 (Res Commun Chem Pathol Pharmacol): dantrolene is hydroxylated by hepatic mixed-function oxidases and also reduced by nitroreductase to aminodantrolene, which inhibits the hepatic mixed-function oxidase system; acetylation blocks that inhibition; "the mercapturic acid conjugation reaction functions as a detoxification mechanism for an electrophilic metabolite of dantrolene" (abstract reconstructed by OpenAlex; species and doses not stated in it) [11]. Büyükokuroglu et al. 2003 (Cell Biochem Funct): 24 rats in three groups of eight; dantrolene 5 mg/kg intraperitoneally 30 minutes before 5 Gy whole-body irradiation lowered plasma and erythrocyte malondialdehyde, raised erythrocyte superoxide dismutase and glutathione peroxidase activity and prevented falls in leukocyte and platelet counts, sampled 2 hours after irradiation (abstract reconstructed by OpenAlex) [10]. Vickers 2017 measured glutathione and ATP in human liver slices and ranked dantrolene as targeting mitochondria more than glutathione; the direction of the glutathione change was not in the abstract [7]. Chakraborty 2024: "decreased oxidative stress" in rats after brain injury, dantrolene 10 mg/kg [9].

Mechanism

Reactive-metabolite formation through nitroreduction with mercapturic acid detoxification [11] is the only named redox mechanism. The antioxidant effects in rodents are reported without a named mechanism in the abstracts read [9][10].

Counter-evidence held on record

Counter-evidence and limits The rodent antioxidant findings come from single-dose pretreatment (irradiation) or injury models and cannot be read as a property of ordinary oral therapy. The hepatocyte and liver-slice panels, the 1983 metabolite paper and the label boxed warning all describe hepatic drug toxicity, not systemic redox status. The Arnold abstract does not state the species, so its direction in humans is not established. Framing caution Do not tell readers that dantrolene is either an antioxidant or an oxidant, and do not imply that antioxidant supplements counter or add to the hepatic risk. The signals point in opposite directions and none is human.

Limits on what this shows

• Why no grade: Dual condition met: no Tier B or C source supports a yellow grade and no consumer claim about dantrolene and copper was found to rebut. This is a disclosed gap, not a finding of safety.

What was searched

PubMed listing "dantrolene copper" (opened on 2026-10-07 after several HTTP 429 refusals of variant queries): four records, none about dantrolene treatment by title (copper toxicity in ducks and in two fish species, and a 1997 smooth-muscle LDL oxidation paper); why each matched the query was not examined; titles only [16]. Variant listings with ceruloplasmin, cupric, copper homeostasis, copper deficiency and trace elements were refused with HTTP 429 and not retried on the same page [16]. Crossref combined query refused (HTTP 429). Label texts for three dantrolene products contain no copper statement [1][2][3]. drugs.com lists no mineral interaction [15]. Repair pass (2026-10-07, later in the same day): re-attempted this category with fresh phrasings across every channel named in the protocol. WebSearch: refused, the shared search budget was exhausted (3 queries across the four categories). PubMed listing pages (dantrolene copper, ceruloplasmin, serum copper): HTTP 429 from the fetch proxy, which asked that the page not be fetched again. Crossref bibliographic search, OpenAlex works search and Semantic Scholar graph search: HTTP 429 each. The wait between attempts was about 6 minutes in total and the proxy kept refusing, so no new record was opened and nothing was added from titles or snippets. The result is unchanged: the gap remains partly tooling-limited and a re-check is still needed.

Gap type

Mostly genuine gap on the single query that opened; partly tooling-limited because the variant queries were refused. Kept independent of Iron (Hard Rule 7); the shared empty search is disclosed in the Overlap map.

Limits on what this shows

• Why no grade: Dual condition met: no Tier B or C source supports a yellow grade for iron, and no circulating claim of a dantrolene iron effect was found to rebut. A labeled anemia is an outcome, not an iron measurement (Hard Rule 2). This is a disclosed gap, not a finding of safety.

What was searched

PubMed listing "dantrolene iron" (opened, nine records, titles only: serotonin syndrome versus neuroleptic malignant syndrome review, a neurodegeneration GeneReviews chapter, a lithium and ferroptosis stem-cell preprint, a clozapine case, nickel and hydrogen peroxide cell studies, a hepcidin osteoblast calcium paper; none about dantrolene effects on iron status) [16]. The hepcidin paper was checked in OpenAlex: no abstract available and dantrolene not found in the record, so nothing is taken from it [18]. Label texts read contain no iron statement; they list "GI bleeding" and "anemia" separately as adverse reactions, with no iron index or link between them [1]. drugs.com lists no mineral interaction [15]. Repair pass (2026-10-07, later in the same day): re-attempted this category with fresh phrasings across every channel named in the protocol. WebSearch: refused, the shared search budget was exhausted (3 queries across the four categories). PubMed listing pages (dantrolene ferritin, serum iron, iron absorption, transferrin saturation): HTTP 429 from the fetch proxy, which asked that the page not be fetched again. Crossref bibliographic search, OpenAlex works search and Semantic Scholar graph search: HTTP 429 each. The wait between attempts was about 6 minutes in total and the proxy kept refusing, so no new record was opened and nothing was added from titles or snippets. The result is unchanged: the gap remains largely tooling-limited beyond the one listing that opened, and a re-check is still needed.

Gap type

Genuine gap on the one channel that opened, with tooling limits (Europe PMC and Semantic Scholar not available; LiverTox refused; no serum ferritin or hemoglobin specific phrasing beyond the "dantrolene anemia" and "dantrolene hemolytic anemia" listings). The labeled anemia and GI bleeding items are filed under Oxygen delivery/utilization and Diarrhea context and are not iron evidence.

Limits on what this shows

• Why no grade: Dual condition met: no Tier B or C evidence supports even a yellow grade, and no circulating consumer claim of a dantrolene microbiome effect was found to rebut. This is a disclosed gap, not a finding of safety. Re-check with 16S, dysbiosis and C. difficile phrasings when access allows.

What was searched

PubMed listing "dantrolene microbiota" (opened on 2026-10-07): one record, a 2025 duck copper-toxicity paper (gut-kidney axis) unrelated to dantrolene therapy, title only [16]. Listings "dantrolene gut microbiota", "dantrolene microbiome", "dantrolene intestinal dysbiosis", "dantrolene gut bacteria feces" and "dantrolene AND microbiota" were each refused with HTTP 429 and were not retried on the same page [16]. Label texts read mention no microbiome, C. difficile or antibiotic-like effect; diarrhea is listed as a frequent adverse reaction without a stated cause [1]. Crossref did not surface a dantrolene microbiome title [17]. Repair pass (2026-10-07, later in the same day): re-attempted this category with fresh phrasings across every channel named in the protocol. WebSearch: refused, the shared search budget was exhausted (3 queries across the four categories). PubMed listing pages (dantrolene gut microbiota and microbiome; 16S, dysbiosis, fecal microbiota and C. difficile phrasings were not reachable): HTTP 429 from the fetch proxy, which asked that the page not be fetched again. Crossref bibliographic search, OpenAlex works search and Semantic Scholar graph search: HTTP 429 each. The wait between attempts was about 6 minutes in total and the proxy kept refusing, so no new record was opened and nothing was added from titles or snippets. The result is unchanged: the gap remains partly tooling-limited and a re-check is still needed.

Gap type

Partly tooling-limited: most phrasings were refused and no 16S, fecal or C. difficile specific query ran, so the one opened query is the main evidence of absence. The label diarrhea statement is filed under the Diarrhea entry as an outcome and is not a microbiome finding.

Limits on what this shows

• Key null findings: No phosphocreatine, lactate, ATP, 31P spectroscopy, muscle biopsy or respirometry result in dantrolene-treated people was retrieved. PubMed listing "dantrolene ATP mitochondria" returned 10 records; the ones with dantrolene named in the title or in an abstract text I read were Vickers [7], Seidlmayer [12], Díaz-Vegas [13] and a 2016 Gaucher disease mouse paper (Liou, title only, not opened); the others were a malignant hyperthermia pathophysiology review and unrelated mitochondrial papers [16]. A Crossref ATP-respiration query returned only generic mitochondrial items and a Reactions Weekly case note [17].
• At-risk subgroups: None established.

Direction

Possible reduction in calcium-dependent mitochondrial ATP production as a downstream result of the drug's intended receptor block, shown only in isolated systems. This is mechanism and intended pharmacology, not a nutrient deficiency, and no human energy output was measured.

Regulatory status

Labels name excitation-contraction uncoupling through reduced sarcoplasmic reticulum calcium release as the mechanism [1][2][3]; none states an ATP or energy-metabolism finding in the sections read. Fatigue, weakness and malaise are listed adverse reactions and are not ATP findings [1].

Population evidence

Seidlmayer et al. 2016 (Cardiovasc Res), adult cardiac myocytes and transgenic mice: endothelin-1 raised mitochondrial calcium uptake and ATP; the uptake was insensitive to Ru360 but attenuated by dantrolene; authors conclude calcium released from the sarcoplasmic reticulum is directed to mitochondria through ryanodine receptors to stimulate ATP production; whether dantrolene itself changed the ATP elevation is not stated in the abstract (reconstructed by OpenAlex) [12]. Díaz-Vegas et al. 2018 (Front Physiol), isolated skeletal muscle fibers: inhibiting RyR1 or IP3R lowered basal oxygen consumption and RyR1 inhibition lowered ATP-linked respiration; dantrolene appears among the keywords but the abstract text read does not name the inhibitor, and methods were not seen, so this source carries the lowest weight in the entry (OpenAlex abstract) [13]. Vickers 2017: glutathione and ATP levels were the functional markers in the human liver-slice model and dantrolene (10 µM) is described as targeting mitochondria more than glutathione; direction and size of the ATP change for dantrolene were not in the abstract text read [7].

Mechanism

Named: ryanodine receptor antagonism reduces sarcoplasmic reticulum to mitochondria calcium transfer, which supports calcium-sensitive dehydrogenases and ATP synthesis in the cited systems [12][13].

Counter-evidence held on record

Counter-evidence and limits Isolated-tissue calcium-handling experiments do not show a reduction in ATP in intact people; muscle ATP is buffered by phosphocreatine, and no clinical measure was found. The cardiomyocyte paper is about calcium routing, not an ATP deficit caused by dantrolene. Shares its mechanism with Mitochondrial burden and Intracellular calcium handling (see Overlap map). Framing caution Do not equate dantrolene muscle weakness or fatigue with low cellular ATP, and do not imply any energy supplement. This is a laboratory mechanism note.

Limits on what this shows

• Key null findings: PubMed listings for dantrolene with hemolytic anemia and dantrolene with anemia returned a 1984 Anesthesiology record on malignant hyperthermia and G6PD deficiency (OpenAlex record with no abstract, so no finding is taken from it), a critical-care symposium proceedings entry and a 1999 case of malignant hyperthermia treated with dantrolene that reported no hematologic outcome in its abstract [16][18]. No hemolysis, methemoglobin, Heinz body or hemoglobin study of dantrolene was found. A listing for dantrolene with erythrocytes was refused with HTTP 429 and not retried on that page [16].
• At-risk subgroups: Not established. Note only that the label lists GI bleeding and anemia separately and nothing links them in the text read.

Direction

Drug toxicity for the label hematologic list (an adverse reaction, not a depletion and not a nutrient-type oxygen-delivery deficiency); protective direction in the rat irradiation model. Anemia is an outcome, not iron deficiency (Hard Rule 2). The intravenous label instruction to "attend to increased oxygen requirements" concerns the hypermetabolic malignant hyperthermia crisis, a disease effect, not a drug effect [3].

Regulatory status

Oral label hematologic adverse reactions as returned by the fetch tool: "Aplastic anemia, anemia, leukopenia, lymphocytic lymphoma, thrombocytopenia"; frequencies and any monitoring schedule were not in the text returned. The gastrointestinal list also includes "GI bleeding" [1]. No hemolysis, methemoglobinemia or G6PD statement was found in the label text returned [1][2][3].

Population evidence

Büyükokuroglu 2003 (rat, n=8 per group, 5 mg/kg i.p. 30 minutes before 5 Gy): lower erythrocyte malondialdehyde, higher SOD and GSH-Px; hemoglobin was measured but its result is not stated in the abstract text read [10]. No clinical hemoglobin study was retrieved.

Mechanism

None named for the label hematologic reactions in any source read. The rat result is attributed by the authors in part to reduced lipid peroxidation and higher antioxidant enzyme activity [10].

Counter-evidence held on record

Counter-evidence and limits The labeled hematologic list is a listing with no incidence, frequency or mechanism in the text returned. The rat study is a radiation model and cannot be extended to oral therapy. Framing caution Do not present this as dantrolene lowering hemoglobin, iron or oxygen delivery through a nutrient pathway. It is a labeled drug-safety list. No iron or other supplement is implied.