Propranolol

Limits on what this shows

• Key negative/null findings: No in vivo human study has replicated the 1977 in-vitro inhibition finding for propranolol at any point in the intervening decades, despite propranolol's decades-long, high-volume clinical use. The ischemia-protection literature runs in the opposite direction from a "burden" framing entirely.
• At-risk subgroups: None defined by human data. Nothing in this evidence identifies a subgroup of propranolol users at elevated risk of mitochondrial harm.

Regulatory status

Not addressed in the propranolol label. No mitochondrial toxicity or biogenesis warning is documented anywhere in the prescribing information already reviewed for this dossier.

Population evidence

Kishi T, Watanabe T, Folkers K, Res Commun Chem Pathol Pharmacol 1977;17:157-164: an in-vitro mitochondrial-enzyme inhibition assay identified via a 2014 peer-reviewed review (PMC4112525), which states directly, "Beta blockers propranolol and metoprolol... have been shown to inhibit CoQ10-dependent enzymes." The 1977 paper's own original full text could not be located or opened in this review; the citation is Tier B and indirect, drawn from a secondary review rather than the primary source. Set against that: Nayler WG, Fassold E, Yepez C, Cardiovasc Res 1978;12(3):152, and Nayler WG, Ferrari R, Williams A, Am J Cardiol 1980, both found propranolol pretreatment protected mitochondrial structure and function in isolated, hypoxic or ischemic heart-muscle preparations; Iwai T, Tanonaka K, Kasahara S, Inoue R, Takeo S, Br J Pharmacol 2002 (DOI 10.1038/sj.bjp.0704724) found propranolol attenuated ischemia-induced mitochondrial dysfunction and improved contractile recovery in a similar model. All three are Tier B animal/ex-vivo studies; none used human tissue and none measured baseline (non-ischemic) mitochondrial biogenesis, density, or respiration.

Mechanism

Named but contested and context-dependent. The 1977 assay's proposed mechanism is direct in-vitro inhibition of CoQ10-dependent mitochondrial enzymes by the drug molecule. The ischemia-protection studies propose the opposite-direction mechanism: beta-blockade lowers myocardial workload and calcium overload during ischemic stress, which preserves rather than damages mitochondrial membrane integrity. These are not the same experimental condition (baseline enzyme assay versus stressed-tissue protection), so the two literatures do not directly contradict each other point-for-point, but neither do they combine into a single coherent "burden" story.

Counter-evidence held on record

This Kishi 1977 source is the same citation trail that, in reviews of beta-blockers generally, is offered as the mechanistic basis for the "beta-blockers deplete CoQ10" consumer claim. The original propranolol dossier's white-tier CoQ10 entry above states that "no Tier A, B, or C source specific to propranolol or any beta-blocker was located showing lowered CoQ10 levels or synthesis inhibition"; this newly located secondary-review citation of the 1977 assay appears to contradict that statement for propranolol by name. Per this expansion's governing instructions, the original entry is preserved exactly as written rather than edited; the discrepancy is logged in the overlap map below for editorial reconciliation, and this new source is used only to support this separately governed Mitochondrial Burden entry, not to retroactively upgrade the CoQ10 white grade. Do not present this as confirmed mitochondrial harm from propranolol. The evidence is Tier B, indirect for the 1977 finding, and directly countered in a different experimental context by three animal studies showing protection. This is an open, unresolved, low-grade signal, not a finding to act on.

Limits on what this shows

• Key negative/null findings: The same Serreau review reports propranolol inducing oxidative stress in aquatic organisms, sturgeon sperm and marine diatoms, at environmental exposure concentrations; this is included here only to show the review's full scope was checked, not cherry-picked, and is explicitly not relevant to human therapeutic dosing, a different species and a different, non-pharmacological exposure route entirely.
• At-risk subgroups: None defined by verified human data.

Regulatory status

Not addressed in the propranolol label. No oxidative-stress marker is named anywhere in the prescribing information.

Population evidence

Taprantzi D et al., "Propranolol reduces systemic oxidative stress and endotoxemia in cirrhotic patients with esophageal varices," Ann Gastroenterol 2017, DOI 10.20524/aog.2017.0222: title, authors, journal, and DOI bibliographically confirmed via Crossref, and propranolol appears specifically in the title as the study drug in a human cirrhotic cohort. Every attempt to open the full text or abstract in this review returned a CAPTCHA or connection block, so no sample size, effect size, or specific statistic from this trial is cited anywhere in this dossier; only its existence and title are on record. Separately, Serreau R, Amirouche A, Benyamina A, Berteina-Raboin S, "Propranolol Hydrochloride Psychiatric Effectiveness and Oxidative Stress: An Update," Oxygen 2024;4(2):9 (DOI 10.3390/oxygen4020009), full text verified directly: this pharmacology review states "the beta-blocker family possesses antioxidant activity," describing propranolol as a direct scavenger of hydroxyl radical and hypochlorous acid that reduces lipid peroxidation, attributed to its lipophilic, membrane-partitioning chemistry rather than to beta-receptor blockade itself. Mohammadi S, Beheshti F, Elyasi S, Jalali M, J Pharm Res Int 2020;32(14):30606: an animal (mouse) study examining propranolol's effect on sperm parameters and oxidative-stress markers; bibliographically confirmed but full text not independently opened in this review, so no specific finding from it is cited.

Mechanism

Named for the antioxidant direction in the Serreau review: direct free-radical scavenging via propranolol's own lipophilic chemistry, distinct from and additional to its beta-adrenergic receptor action. No mechanism for propranolol causing oxidative stress in human tissue at therapeutic doses was identified in this review.

Counter-evidence held on record

The Taprantzi 2017 record could not be verified in full text despite repeated attempts and is held only as a bibliographic entry; per this protocol's citation-integrity rule, an unverified Tier A record cannot support any grade above yellow regardless of how promising its title reads, and no statistic from it appears anywhere in this dossier. Never present this as "propranolol reduces oxidative stress, so antioxidant nutrients matter less" or as a license to skip antioxidant-relevant nutrients. The evidence remains theoretical and Tier B for confirmed human status data; this entry exists to correct the record toward what was actually found, not to make a wellness claim in either direction.

Limits on what this shows

• Why no grade: Yellow requires at least mechanistic plausibility (Tier B) or class extrapolation (Tier C); neither exists here. White requires an actual circulating consumer claim to rebut; the consumer nutrient-depletion sources already reviewed for propranolol name only coenzyme Q10 and melatonin (see the original claims-that-fail-verification table above), and no separate search surfaced a copper-specific claim for propranolol or beta-blockers generally. Both preconditions for a color grade are absent, so this is a genuine gap, not a safety finding.
• What would fill this: A cohort or interventional study measuring serum copper or ceruloplasmin before and after propranolol initiation, or even a single case report naming propranolol specifically, would be sufficient to move this to yellow.

Regulatory status

Not addressed in the propranolol label. No mineral interaction beyond the already-documented protein-meal bioavailability effect (drug absorption, not a mineral interaction) is described anywhere in the prescribing information reviewed for this dossier.

Population evidence

None located. Dedicated searches for propranolol plus copper, trace element, or ceruloplasmin returned no propranolol-specific or beta-blocker-class result of any kind. The closest topical match found by search proximity, Vivoli G et al., "Zinc, copper, and zinc- or copper-dependent enzymes in human hypertension," Biol Trace Elem Res 1995, studies hypertensive patients generally, not beta-blocker treatment specifically, and is not cited as evidence for this entry.

Mechanism

None identified. Propranolol does not chelate minerals, does not alter gastric pH by any named mechanism, is not renally wasting, and has no documented transporter interaction; mechanism screen categories A through I all return absent for copper.

Counter-evidence held on record

Framing caution for the consumer-facing surface An evidence gap is not a clean bill of health. This must never be shown to a reader as "propranolol is safe for copper levels"; it must read as "not enough evidence exists to grade this."

Limits on what this shows

• Why no grade: No Tier B mechanistic or Tier C class-extrapolation evidence supports a depletion or disturbance mechanism, and the one disease-context source found points the opposite direction from a depletion story, so it cannot be used to construct even a class-extrapolated yellow. No circulating consumer claim naming propranolol or beta-blockers and iron was found. Both preconditions for a color grade are absent.
• What would fill this: A study directly measuring iron status (ferritin, transferrin saturation, hemoglobin) in propranolol-treated patients against a matched untreated or alternative-therapy comparator, ideally stratified by indication (hypertension versus variceal prophylaxis) to separate any drug effect from disease-driven blood loss.

Regulatory status

Not addressed in the propranolol label.

Population evidence

None located specific to propranolol and iron, ferritin, or hemoglobin. Because propranolol is used in cirrhosis and portal hypertension for variceal-bleeding prophylaxis, this review specifically checked whether chronic gastrointestinal blood loss in that population might create an indication-linked iron-deficiency confound of the kind flagged for other drugs in this class. The one relevant source found, NCBI Bookshelf/StatPearls, "Esophageal Varices" (NBK448078), full text verified directly, states that occult bleeding and anemia are uncommon as an initial presentation of esophageal varices, and that nonselective beta-blockers, propranolol named among them, reduce the risk of a first variceal bleed from about 25% to about 15% in primary prophylaxis. The drug's documented action works against, not toward, a bleeding-driven iron-loss pathway in this population, the opposite of what would be needed to support even a cautious class-level confounding-by-indication flag.

Mechanism

None identified. Mechanism screen categories A through I all return absent for iron.

Counter-evidence held on record

Framing caution for the consumer-facing surface An evidence gap is not a clean bill of health, and a protective finding for one bleeding-related pathway is not a general statement about iron status on propranolol. This must read as "not enough evidence exists to grade this," not as reassurance.

Limits on what this shows

• Key negative/null findings: No study of gut microbiome composition itself (16S sequencing, diversity indices, or similar) in propranolol-treated patients, cirrhotic or otherwise, was located. The Reiberger findings concern permeability and inflammatory markers, not microbial community structure, so even if fully verified they would not directly confirm or refute a claim about the "gut microbiome" as that term is commonly used.
• At-risk subgroups: Cirrhotic patients with portal hypertension are the only population in which this pathway has even indirect support. Confounding by indication applies fully: cirrhosis itself is independently, and much more strongly, associated with gut dysbiosis and bacterial translocation than any documented propranolol effect, and any propranolol-associated change would need to be separated from the disease's own well-established microbiome effects.

Regulatory status

Not addressed in the propranolol label. Propranolol is not an antimicrobial and has no named gastric-pH or transit-time effect; mechanism screen category G (microbiome disruption) has no direct pathway identified for the beta-adrenergic blockade mechanism itself.

Population evidence

Reiberger T, Ferlitsch A, Payer BA, et al., "Non-selective betablocker therapy decreases intestinal permeability and serum levels of LBP and IL-6 in patients with cirrhosis," J Hepatol 2013;58(5):911-921, DOI 10.1016/j.jhep.2012.12.011: authors, journal, volume, and pages bibliographically confirmed via Crossref. The title states nonselective beta-blocker therapy decreases intestinal permeability and serum lipopolysaccharide-binding protein and interleukin-6, markers of bacterial translocation and systemic inflammation, in cirrhotic patients. Full text and abstract could not be opened in this review, so whether propranolol specifically, as opposed to another nonselective beta-blocker, was the study drug, and the exact effect size, could not be verified; no statistic is cited from it here. A related reference, NCBI Bookshelf/StatPearls, "Esophageal Varices" (NBK448078), full text verified directly, confirms the underlying mechanism already on file for this drug: "Nonselective beta-blockers reduce portal pressure and decrease the risk of the first bleed from 25% to 15% in primary prophylaxis," naming propranolol among the agents used.

Mechanism

The proposed pathway, per the title of the Reiberger source and the confirmed portal-pressure mechanism, is hemodynamic: lowering portal pressure reduces gut mucosal congestion and bacterial translocation. This is not a direct antimicrobial or fermentation-pathway effect on the microbiome itself, and is mechanistically distinct from how drugs with clear microbiome mechanisms (antibiotics, proton pump inhibitors) act.

Counter-evidence held on record

A separate clinical controversy exists in hepatology, sometimes called the "window hypothesis" (Tholey D, Roth N, Schiano T, Clin Liver Dis 2018, DOI 10.1002/cld.700), about whether nonselective beta-blockers should be continued in decompensated cirrhosis with refractory ascites; that debate concerns clinical outcomes such as mortality and acute kidney injury, not microbiome or nutrient status specifically, and is listed in sources for completeness but not used to support any grade in this entry. This must not be read as confirmation of either harm or benefit to the gut microbiome from propranolol. It is a cautious, unverified, disease-population-specific signal pointing away from risk, not a wellness claim, and must never be generalized to propranolol users without cirrhosis.

Limits on what this shows

• Key negative/null findings: Patient-reported fatigue, exercise intolerance, and cold hands or feet on propranolol are recognized, labeled pharmacodynamic effects, not signs of anemia or a nutrient-mediated failure of oxygen carriage. Filing them as a nutrient deficiency would violate this protocol's hard rule against relabeling a drug's own known clinical mechanism as a deficiency finding.
• At-risk subgroups: Patients titrating onto propranolol or on higher doses are most likely to notice these effects. Patients with Raynaud's phenomenon or peripheral vascular disease are more likely to notice the vasoconstrictive effect specifically, consistent with general beta-blocker prescribing caution rather than any propranolol-specific nutrient finding.

Regulatory status

The propranolol label already reviewed for this dossier documents propranolol as a competitive, non-selective beta-1/beta-2 adrenergic antagonist. Reduced heart rate, contractility, and cardiac output are the mechanistic basis for its antihypertensive and antianginal indications, lowering myocardial oxygen demand by design. Beta-2 blockade leaving alpha-mediated peripheral vasoconstriction unopposed is the documented basis for cold extremities as a labeled adverse reaction of non-selective beta-blockade generally.

Population evidence

This is a mechanism clarification drawn from the drug's own labeled pharmacology already on file in this dossier's PK prescreen and headline finding, not a nutrient-status finding, so it is not held to the same population-evidence bar as a depletion claim. No study located in this review attributes reduced tissue oxygen delivery on propranolol to a nutrient deficiency (iron-deficiency anemia, B12) rather than to the drug's own hemodynamic and vasomotor action.

Mechanism

Named, and already established elsewhere in this dossier: non-selective beta blockade lowers heart rate, contractility, and myocardial oxygen consumption via beta-1 blockade, while beta-2 blockade leaves alpha-adrenergic peripheral vasoconstriction unopposed. Together these explain both reduced cardiac oxygen demand (the drug's therapeutic goal) and the commonly reported cold-extremities effect (a labeled adverse reaction), without any nutrient pathway involved.

Counter-evidence held on record

No evidence or mechanism located in this review links propranolol to impaired hemoglobin synthesis, reduced arterial oxygen saturation, or any other nutrient-mediated defect in oxygen-carrying capacity. The entire basis for this entry is the drug's own labeled, intended hemodynamic and vasomotor action. Never present reduced heart rate, cold extremities, or reported fatigue on propranolol as evidence of "low oxygen" needing a nutrient or supplement fix. This is pharmacology, not deficiency; bothersome symptoms belong in a conversation with the prescriber about dose or drug choice.

Limits on what this shows

• Key negative/null findings: No study located in this review measures direct cellular ATP flux, phosphocreatine/ATP ratio by 31P-MRS, or mitochondrial ATP-synthase activity in propranolol-treated tissue, in burn patients or any other population. The evidence above concerns whole-body energy expenditure and catabolic markers, a related but distinct endpoint from cellular ATP synthesis itself, and should not be conflated with it.
• At-risk subgroups: This evidence is confined to children with major burn injury (over 40% total body surface area) under specialized critical-care dosing and monitoring. It does not generalize to adult hypertension, migraine, tremor, or anxiety indications, which were not studied for this outcome and use different, non-weight-tiered dosing; confounding by indication applies fully, mirroring the caution already on file for the potassium/hemangioma entry above.

Regulatory status

Burn-hypermetabolism use is established in specialized burn-care clinical literature, not part of the core FDA-approved indications reviewed in this dossier's original label review; treated here as clinical literature, not label text, mirroring the framing already used for the potassium/infantile-hemangioma entry above.

Population evidence

Herndon DN, Hart DW, Wolf SE, Chinkes DL, Wolfe RR, "Reversal of Catabolism by Beta-Blockade after Severe Burns," N Engl J Med 2001;345(17):1223-1229, DOI 10.1056/NEJMoa010342: bibliographically confirmed via two independent metadata sources (Crossref, Semantic Scholar; title, authors, journal, volume, pages, and DOI all cross-matched). Full text and abstract were blocked by the publisher at every access attempt in this review, so no specific statistic, sample size, or effect size from this trial is cited here. Norbury W et al., "Propranolol attenuates factors affecting hypermetabolism in pediatric burn patients," Crit Care 2007;11(Suppl 2):P152, DOI 10.1186/cc5312: full text verified directly in this review. Randomized controlled trial, 66 children with burns exceeding 40% total body surface area, standard burn care (n=33) versus standard care plus propranolol 0.5-1.5 mg/kg every 6 hours for over 21 days (n=33). Propranolol reduced heart rate by about 10% and improved stroke volume throughout the acute hospital stay, decreased resting energy expenditure at discharge, increased anabolic hormones (IGF-1, IGFBP-3, growth hormone) and prealbumin, reduced circulating fatty acids and inflammatory markers, and was associated with lower infection incidence (60% versus 87% on weekly tissue biopsy) in this trial. The authors concluded propranolol was "a safe and efficacious modulator of the postburn response" in this population.

Mechanism

Named: beta-adrenergic blockade blunts the catecholamine surge that drives the hypermetabolic, hypercatabolic stress response to severe burn injury, reducing resting energy expenditure and net protein and lipid catabolism. This is an anti-catabolic, protein-sparing action, the direct opposite of a nutrient-depleting mechanism.

Counter-evidence held on record

This is verified, real, drug-specific human evidence, stronger than most entries in this dossier, but it describes the drug's own intended pharmacodynamic action in a critical-illness population, not a nutrient deficiency in ordinary users, and this protocol's hard rule against relabeling a drug's known clinical effect as a nutrient finding applies directly. Never present reduced resting energy expenditure on propranolol as evidence of "low ATP" or "low energy" needing supplementation in typical outpatient users. The trial population is severely burned children under ICU-level nutritional support and monitoring, not a general population analog, and no dosing or supplement recommendation follows from this entry for any population.