AICAR (Acadesine)

Overview

AICAR (acadesine) is an AMPK activator — a cell-permeable nucleoside / adenosine analog (5-aminoimidazole-4-carboxamide ribonucleoside, or "AICA-riboside"). It is not a peptide and not a SARM: it has zero androgen-receptor activity, and its real mechanism is activation of AMP-activated protein kinase (AMPK), not androgen-receptor modulation. Calling it a "SARM" is simply wrong.

Its fame comes from a single landmark rodent result: in sedentary mice, four weeks of AICAR alone increased running endurance by about 44% (Narkar et al., Cell 2008) — the "exercise in a bottle" finding that got AICAR added to the WADA Prohibited List in 2009. That physique/endurance evidence is rodent only. Human efficacy for endurance or body composition is unestablished, and USADA states that AICAR has not been extensively studied in people.

Clinically, AICAR was developed as "acadesine": a Phase III cardiac-surgery (CABG) cardioprotection program that was terminated for futility in 2010, and a Phase I/II trial in relapsed/refractory chronic lymphocytic leukemia — neither reached approval. It is not an approved medicine for physique or performance, and it is not a "milder/safer/legal alternative" to anything.

Chemistry and structure

Mechanism of action

• Phosphorylated intracellularly to ZMP, an AMP mimetic. [In vitro] AICAR is transported into cells and phosphorylated by adenosine kinase to its monophosphate ZMP (AICA ribotide), which structurally mimics AMP. ZMP binds the γ-subunit of AMPK and allosterically activates the kinase without changing the true AMP:ATP ratio, making AICAR a pharmacological AMP mimetic.
• AMPK activation drives PGC-1α and mitochondrial biogenesis. [Animal] AMPK activation promotes PGC-1α expression, mitochondrial biogenesis, and an oxidative, fatigue-resistant muscle phenotype. A single AICAR injection in mice increased mRNA of PGC-1α isoforms; four weeks of AICAR induced type I (slow-twitch) fiber-associated metabolic genes.
• Increases insulin-independent glucose uptake and fat oxidation. [Animal] AMPK activation increases insulin-independent glucose uptake (GLUT4 translocation) and fatty-acid oxidation. This is the basis for AICAR's use as a metabolic research tool and the rationale for "exercise-mimetic" claims, demonstrated in rodent and cell models.
• ~44% endurance gain in the landmark mouse study. [Animal] In Narkar et al., Cell 2008 (PMID 18674809), AICAR alone increased running endurance by ~44% in sedentary mice via the AMPK–PPARδ axis; AMPK activation was sufficient to enhance endurance, and combining it with the PPARδ agonist GW1516 potentiated the effect.
• Many effects are AMPK-independent. [In vitro] A systematic review (Višnjić et al., Cells 2021, PMC8147799) notes that AICAr is roughly 40–50× less potent than AMP at AMPK and accumulates at high cytoplasmic concentrations, producing effects on nucleotide synthesis, hypoxia signaling and cancer that do not require AMPK — urging caution when interpreting AICAr-based studies.
• Selective pro-apoptotic activity in B-CLL. [In vitro] In B-cell chronic lymphocytic leukemia, acadesine selectively induces apoptosis (partly AMPK-independent) in B-CLL cells but not T lymphocytes — the rationale for the hematology trials.
• Human benefit is unestablished. [Human] USADA states AICAR "has not been extensively studied in people"; it is an experimental compound not approved for human therapeutic use. The exercise-mimetic evidence is rodent, not human.

Research and evidence

The most-cited AICAR result is a rodent study, not a human trial. The human record belongs to the drug "acadesine," which was tested for entirely different indications (cardiac surgery, leukemia) and never approved.

Precise NCT identifiers for the terminated CABG Phase III and the CLL Phase I/II programs were not located in sources and are cited by publication/company record instead.

Status and regulation

• Approval: Not approved anywhere for physique or performance. The clinical drug "acadesine" reached Phase III for CABG cardioprotection but was terminated for futility in 2010; the Phase I/II CLL program did not reach approval.
• Highest phase: Phase III (cardiac surgery, terminated for futility). No physique/endurance human trials exist.
• Developers: Studied clinically as "acadesine" — originally Gensia Sicor / Gensia Inc., later Schering AG / Pericor Therapeutics (cardiac surgery) and Advancell / Crystal Genomics (CLL). No approved physique/performance product exists.
• WADA: Prohibited at all times (in- and out-of-competition) under S4.4 — Hormone and Metabolic Modulators, as an activator of AMP-activated protein kinase (AMPK); AICAR is named explicitly. Banned since 2009.

Safety

Documented human safety data come only from IV acadesine infusion in cardiac-surgery and leukemia patients — not from the vialed "research chemical" doses and routes marketed to consumers.

• Hyperuricemia / elevated uric acid burden. [Human] AICAR's purine-nucleoside structure increases uric acid load; hyperuricemia was a consistently reported adverse event across the CABG and CLL clinical programs. Relevant to gout and renal risk.
• Transient hematologic toxicity. [Human] Modest grade 1–2, transient anemia and/or thrombocytopenia was reported in the Phase I/II CLL study, with recovery to baseline within days in most patients.
• Risk from excessive or mistargeted AMPK activation. [Hypothesis] USADA/WADA note that too much AMPK activation, or activation in the wrong tissue, can cause serious effects including neurodegeneration or blocking cell division. This is mechanistic caution, not a documented consumer outcome.
• Extensive AMPK-independent, off-target activity. [In vitro] AICAr is ~40–50× weaker than AMP at AMPK and accumulates to high intracellular levels, producing AMPK-independent effects on nucleotide synthesis, hypoxia signaling and cancer pathways — meaning its full effect profile in humans is poorly characterized and hard to predict.
• No established human safety profile for physique/performance dosing. [Human] Clinical safety data exist only for IV acadesine infusion protocols in patients — not for consumer "research chemical" doses or routes. There is no validated human safety dataset for physique or endurance use.

Product mislabeling and contamination reality. Van Wagoner et al. (JAMA 2017;318(20):2004-2010; PMID 29183075) chemically analyzed 44 products sold as SARMs: only 52% contained the labeled compound, 39% contained a different unapproved drug, and 9% contained no active compound at all. This applies broadly to grey-market "research chemicals" — a label reading "AICAR" is not a reliable statement of contents or purity. [Human]

Legal status

Legal status is not assessed here. AICAR is framed as a research reagent / experimental compound, not as a product with any assessed human-use legality. Nothing here should be read as saying it is "safe" or "legal to take."

Note that WADA status is a separate axis from legality: AICAR is prohibited in sport at all times under S4.4 regardless of any jurisdiction's drug-law treatment. A compound can be a legal-to-possess research chemical in some places and still be a bannable doping offense in sport.

How it compares

• Cardarine (GW-501516) — a PPARδ agonist, also rodent "exercise-mimetic" hype, also WADA-prohibited; a different (PPARδ, not AMPK) non-androgen mechanism.
• Stenabolic (SR9009) — a Rev-ErbA ligand marketed on similar metabolic/endurance claims; like AICAR, not a SARM and not a peptide.

All three are grouped in the grey market as "endurance/metabolic" compounds, but each has a distinct non-androgen mechanism, and none is an approved medicine for physique or performance.

Common misconceptions

• "AICAR is a SARM." No. It has zero androgen-receptor activity. Its mechanism is AMPK activation — it is a nucleoside/adenosine analog, not an androgen-receptor modulator.
• "AICAR is a peptide." No. It is a small-molecule nucleoside (C9H14N4O5), not a peptide.
• "Studies prove it boosts human endurance." The ~44% endurance result is in mice. No human efficacy trials for endurance or body composition exist; USADA states it has not been extensively studied in people.
• "It's an approved exercise drug." No. The clinical program ("acadesine") targeted cardiac surgery and leukemia, was terminated for futility in cardiac surgery, and never reached approval for any indication.
• "It's a safer/legal alternative to steroids." No. It is not an approved medicine, it is WADA-prohibited at all times, and its human safety profile at physique doses is unestablished.
• "A vial labeled AICAR contains AICAR." Not reliably. Grey-market "research chemicals" are frequently mislabeled (JAMA 2017) — labels are not a reliable statement of contents or purity.