GC-1 (sobetirome, QRX-431) is a synthetic, iodine-free analogue of thyroid hormone designed in Thomas Scanlan's laboratory to activate thyroid hormone receptor beta.
Amounts reported for GC-1 are listed under Reported protocols, each with its source and study kind. No amount ladder is inferred from them. This is educational source context, not a protocol or recommendation.
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Human study rows are described per source under Reported protocols; they belong to their trial populations and are not a general amount.
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What published studies and recent community write-ups report about amounts, timing and course length. 2 clinical, 1 preclinical and 1 community-reported rows, each linked to its source. These are descriptions of what others report, not instructions, and nothing here is medical advice.
| Context | Dose | Frequency | Route | Course | Source |
|---|---|---|---|---|---|
| Clinical2 rows | |||||
| Phase 1 single rising dose study32 healthy male volunteers not selected for high cholesterol, on a low-cholesterol diet from one week before randomisation | Single doses of 1, 5, 25, 50, 75, 150, 300 or 450 mcg | Single dose, crossover design | Oral | Single dose with follow-up; the largest LDL fall came 72 hours after dosingNot applicable | QuatRx Pharmaceuticals via BioSpace2008 |
| LDL cholesterol fell by up to 22% at the highest doses against 2% on placebo, and the sponsor reported all doses as well tolerated with no notable safety concerns. The results exist only as a company press release and a regulatory substance record; no peer-reviewed publication of the trial has appeared. | |||||
| Phase 1 multiple rising dose study24 healthy male volunteers | 10, 30, 70 or 100 mcg | Once daily | Oral | 14 daysNot applicable | National Center for Advancing Translational Sciences2026 |
| LDL cholesterol fell by up to 41% at 100 mcg a day against an overall 5% fall on placebo. The NCATS substance record lists these dose levels and notes that development for lipid disorders and obesity was later discontinued; these two studies remain the only human exposure data for sobetirome. | |||||
| Preclinical1 row | |||||
| Rat and monkey selectivity studyCholesterol-fed rats, and cynomolgus monkeys, each treated for 7 days | In rats the half-maximal cholesterol-lowering dose was 190 nmol/kg per day (about 62 mcg/kg), against 5451 nmol/kg per day to raise heart rate by 15%; metabolic rate rose 5% at 477 nmol/kg per day | Daily | Not stated | 7 daysNot applicable | Endocrinology (PubMed)2004 |
| GC-1 lowered cholesterol about 30 times more potently than it caused tachycardia, where T3 showed no separation, and in monkeys it cut cholesterol and lipoprotein(a) without tachycardia while both GC-1 and T3 reduced body weight by about 4%. The study came from Bristol-Myers Squibb with the compound's inventors; animal doses in nanomoles per kilogram do not translate to a human amount. | |||||
| Community-reported1 row | |||||
| Vendor liquid and capsule listing | 100 mcg per capsule (60 capsules), or 100 mcg/mL in a 30 mL liquid | Not stated | Oral capsule or liquid research preparation | Not stated | Community resource2026 |
| This is a vendor claim: the vendor sells GC-1 in both formats for thyroid hormone receptor beta research and states no dosing. One capsule equals the highest daily dose in the two-week phase 1 study. The vendor's own research guide says it describes no human effect, dose or use, and records that both registered adrenoleukodystrophy trials (NCT01787578 and NCT03196765) were withdrawn with zero enrolment. | |||||
Plus 2 community resources (dosing guides, forum threads and vendor write-ups), reported above but not linked.
GC-1 (sobetirome, QRX-431) is a synthetic, iodine-free analogue of thyroid hormone designed in Thomas Scanlan's laboratory to activate thyroid hormone receptor beta, the liver form that lowers cholesterol, while sparing the heart's receptor alpha. In rats and monkeys it lowered cholesterol and lipoprotein(a) with little tachycardia, and two phase 1 studies in healthy men reported by QuatRx in January 2008 found LDL cholesterol falling by up to 41% after two weeks at 100 micrograms a day. Development stopped after phase 1, two later adrenoleukodystrophy trials were withdrawn before enrolling anyone, and the compound has never been approved.
These themes describe recurring questions in published research. They are not claims of effectiveness or recommendations for use.
Energy balance, body composition and incretin signaling.
LDL cholesterol fell by up to 22% at the highest doses against 2% on placebo, and the sponsor reported all doses as well tolerated with no notable safety concerns. The results exist only as a company press release and.
LDL cholesterol fell by up to 41% at 100 mcg a day against an overall 5% fall on placebo. The NCATS substance record lists these dose levels and notes that development for lipid disorders and obesity was later.
GC-1 lowered cholesterol about 30 times more potently than it caused tachycardia, where T3 showed no separation, and in monkeys it cut cholesterol and lipoprotein(a) without tachycardia while both GC-1 and T3 reduced.
This is a vendor claim: the vendor sells GC-1 in both formats for thyroid hormone receptor beta research and states no dosing. One capsule equals the highest daily dose in the two-week phase 1 study. The vendor's own.
Study models remain visible so laboratory and animal findings are not mistaken for established human outcomes.
2 protocol rows on this page come from human trials, trial registrations, regulator labels or reviews of human data. Approval status and populations are stated per row.
1 protocol row describe animal, cell or toxicology work. Amounts from these rows do not translate to people.
1 row record what blogs, vendor write-ups or forums describe for GC-1. None has been verified against primary literature.
Sequence, synonyms and registry identifiers as recorded in PubChem, the National Library of Medicine's open chemistry database. Formula, mass and CAS number are summarized at the top of the page.
Sobetirome, GC-1, QRX-431, UNII XQ31741E9Q, CHEMBL107400, CHEBI:79988, Sob-AM2 (brain-penetrant amide prodrug)
QNAZTOHXCZPOSA-UHFFFAOYSA-N
2-[4-[(4-hydroxy-3-propan-2-ylphenyl)methyl]-3,5-dimethylphenoxy]acetic acid
5 curated references, each with its journal, year and study model, plus 2 community resources reported but not linked.