Andarine (S4) 60 capsules

Andarine (S4) – SARM (Research Use Only) research reagent

Chemical reagent intended exclusively for laboratory tests (Research Use Only). It is not a medicinal product, dietary supplement or food. It is not intended for administration to humans or animals outside a controlled experimental environment.

Andarine (S4) is one of the most frequently cited nonsteroidal selective androgen receptor modulators in the preclinical literature. We offer the material as a research reagent in capsule form, with HPLC purity ≥ 98%, identity confirmation by mass spectrometry and a certificate of analysis for each batch. The following description organizes what is known from the scientific literature about this compound – including its recognizable visual signal and its status as a prohibited substance in sports.

What is Andarine (S4) – origin and place in the SARM class

Andarine (S4) is among the earliest non-steroidal selective androgen receptor modulators (SARMs), as described in the literature. The association operates under laboratory codes GTx-007 and S-4, and its common name – Andarine – has become established in the literature and laboratory jargon.

Work on this compound was conducted by a research team James T. Dalton — a chemist and pharmacologist whose group (first in the academic environment, then within the company GTx) laid the foundations for an entire class of non-steroidal SARMs. It was from this same line of research that later enobosarm (ostarin), a compound that went much further in clinical development, was derived. Andarine (S4), however, remained primarily a preclinical tool – a reference point on which the very concept of tissue selectivity was tested.

In terms of chemical structure, Andarine (S4) belongs to a class arylpropionamides. Historically, arylpropionamides originate from the modification of anti-androgen structures (such as bicalutamide), which, in the course of work on the structure-activity relationship, were transformed into molecules with an agonistic profile towards the androgen receptor in selected tissues. Narayanan, Coss, and Dalton (2018) describe this class development journey: from antiandrogen chemistry, through the first nonsteroidal AR agonists, to compounds designed to separate anabolic and androgenic responses in animal models.

In research practice, Andarine (S4) is today treated as experimental tool — reference ligand in work on androgen receptor pharmacology, analytical chemistry and anti-doping detection. It is not registered as a medicinal product with any regulatory agency.

Chemical characteristics of Andarine (S4) – reagent parameters

The identity and purity of the material in a given batch is confirmed by the certificate of analysis (COA) assigned to the batch number. The data in the table is informative and descriptive substance as a reagent, and not the properties of any product intended for humans.

Androgen receptor – how tissue selectivity arises

To understand what the “selectivity” of an androgen receptor modulator would be, it is worth taking a look at the receptor itself. Androgen receptor (AR) is a protein from the nuclear receptor family, composed of several clearly separated fragments:

• N-terminal domain (NTD) — the most variable fragment, responsible for transcription activation and most interactions with accompanying proteins;
• DNA binding domain (DBD) — recognizes specific sequences in the promoters of target genes;
• hinge region — a linker containing a nuclear localization signal;
• Ligand binding domain (LBD) — a pocket in which the androgen molecule or SARM molecule is deposited.

The mechanics are simply as follows. The ligand enters the LBD pocket, which causes conformational change receptor – it arranges its helices differently, especially helix 12, which closes the pocket like a lid. The receptor surface shaped in this way determines which regulatory proteins will stick to it. The receptor releases chaperones, translocates to the cell nucleus, dimerizes and binds DNA in androgen response regions.

Only at this point does the most interesting thing start to happen: the receptor itself does not “turn on” the genes. He is recruiting for himself coactivators (including the p160 / SRC-1, SRC-2, SRC-3 family) or corepressors (like NCoR and SMRT). They translate the presence of the ligand into real transcriptional activity. Because different tissues have different repertoires and different concentrations of these accessory proteins, the same receptor with the same ligand can give a different response in muscle, bone and prostate tissue. In addition, there is local androgen metabolism – in some tissues, enzymes transform the signaling molecule into a stronger form.

This difference is the theoretical basis of the SARM concept: a non-steroidal molecule, by binding the receptor in a slightly different way than testosterone, forces a different conformation and a different recruitment pattern of coregulators – and therefore, in principle, a different response in different tissues. Narayanan et al. (2018) discuss this model as a basis for whole-classroom design.

Why SARM is not an anabolic steroid

The distinction is chemical, not marketing. Anabolic-androgenic steroids have steroid core — four-ring skeleton, such as in testosterone. Andarine (S4) and other arylpropionamides do not have such a core: they are molecules non-steroidal, with a completely different architecture.

The consequence is specific and well documented in the literature: non-steroidal compounds they are not substrates of 5α-reductase or aromatase. This means that neither dihydrotestosterone (DHT) nor estradiol are produced in the model organism – two metabolites responsible for a large part of the androgenic and estrogenic profile of classic steroids. Solomon et al. (2019) and Narayanan et al. (2018) point to this point as the main pharmacological difference between the classes.

However, chemical distinction does not mean “safety”. The receptor dependence remains the same, and the signals observed in the studies – as described below – include, among others: influence on the hormonal axis and the lipid profile.

Andarine mechanism – what has been described in studies

In the preclinical literature, Andarine (S4) is described as androgen receptor binding ligand with agonistic or partially agonistic activity, depending on the tissue and model. The feature that has attracted the interest of researchers is reported tissue selectivity: in animal models, the compound showed a different activity profile in muscle and bone tissue compared to reproductive tissues.

In the literature, S4 is sometimes described as partial agonist — a molecule that produces a weaker response than a full agonist in highly androgen-dependent tissues, and a relatively more pronounced response in muscle and bone tissue. Such a profile (strong activity in one compartment, partial activity in another) is what is called selective modulation in pharmacology.

Also noted short half-life compound in animal models – an important parameter for experimental planning and for the interpretation of pharmacokinetic data, as well as for analytical chemistry, because it translates into the metabolite detection window.

All of these observations come from laboratory conditions and animal models. They do not constitute a description of an effect in humans and cannot be interpreted as such.

Overview of preclinical studies on Andarine (S4)

Gao et al. (2005) – orchidectomized rat model

Work published in Endocrinology is the most frequently cited source for Andarine (S4).

Study design. A classic model of androgen deficiency in rodents was used: rats subjected to orchidectomy (removal of the gonads), which experience muscle tissue atrophy, bone loss and changes in body composition. This model serves as a standard tool for assessing whether a test compound is able to reproduce the anabolic effects of androgens in the absence of an endogenous source of the hormone. The animals were administered the test compound, and then muscle parameters, bone mineral density and body composition were assessed, compared with control groups.

What was reported. In this model, the authors report an improvement in muscle strength and a beneficial change in body composition, as well as the prevention of bone loss in animals receiving the compound, compared to control animals. The results were interpreted as evidence of the anabolic effect of the ligand in muscle and bone tissue, with a relatively weaker response in androgen-dependent tissues.

Limitations. This is a study on rodents, in a model of surgically induced androgen deficiency – a situation that does not correspond to the physiology of a healthy human. Short observation period, small group size, lack of clinically important endpoints (such as functional capacity or fractures), lack of long-term safety data. The extrapolation of these results to humans is unauthorized — and that’s how they should be read.

Kearbey et al. (2007) – ovariectomized rat model

The second fundamental work, published in Pharmaceutical Research, moves the research question to bone ground.

Study design. The ovariectomized rat model is the standard model postmenopausal osteoporosis — removal of the ovaries leads to accelerated loss of bone mass and an increase in the percentage of adipose tissue, analogous to the changes observed after menopause. The test compound was administered to the animals and bone mineral density, bone microarchitecture parameters and body composition were assessed.

What was reported. The authors report prevention of bone loss and reduction of fat tissue in animals receiving the compound. The result was treated as a premise for further work on the use of the SARM class in bone diseases.

Limitations. Analogously: rodent model, surgically induced state of sex hormone deficiency, surrogate endpoints (bone density instead of hard points such as fractures), no translation to humans.

Andarine evidence base (S4) – rodents, not clinic

A point that needs to be made clear: evidence for Andarine (S4) comes primarily from rodent models. Unlike enobosarm (starine), which has undergone clinical trials involving large patient populations, Andarine (S4) has not completed advanced phase III clinical trials. Human data are limited to scattered observations, case reports, toxicological analyzes and self-reports.

Bond et al. (2025), in a critical review SARM class, indicate that enthusiasm for this group of compounds has outpaced the quality of the data: the promise of an “anabolic without androgenic effects” has not been confirmed at the level of evidence required for drug registration, and the safety profile remains insufficiently characterized. For a researcher working with S4, this is first-class information: the compound is a tool, not a therapeutic candidate with a fixed profile.

Andarine and vision – xanthopsia as a hallmark of S4

If any element of Andarine (S4)’s characteristics is immediately recognizable, it is this: reported visual disturbances.

Two phenomena have been repeatedly described in reports and literature regarding this relationship:

• xanthopsia — a yellowish tint to vision, described as a “yellow filter” superimposed on the image;
• worsened night vision — prolonged adaptation to darkness and difficulty in distinguishing objects in low light.

Mechanistic hypothesis. Explanations proposed in the literature refer to the affinity of the compound towards the receptors present in retina. The retina is not a hormonally neutral tissue – nuclear receptors are present in it, and photoreceptors (cones and rods) and cells processing the visual signal are subject to regulation depending on signaling cascades that include receptor activity. It was suggested that the interaction of the ligand with this environment temporarily disrupts the processing of the visual signal – in particular the function of the rods responsible for vision in low light conditions – which would explain both the change in color perception and the deterioration of vision after dark. This is a hypothesis, not a relationship confirmed by an interventional study in humans.

Reversibility. In available reports, the effect is described as reversible — resolving after cessation of exposure to the compound. However, such reports have limited evidentiary value.

Evidence framework. Much of the data on visual impairment in the context of S4 comes from self-reports. Joshi et al. (2025) analyzed reports of adverse effects of SARM compounds reported on social media – this work systematizes what people they report, and directly points out the limitations of such material: no verification of the identity of the substance, no control, no analytical confirmation, risk of selection effect. In other words: the visual signal in the case of S4 is there consistent and repeated many times, but its evidence base remains weak in terms of clinical trial methodology.

We provide this information as an honest, recognizable characterization of the compound – not as a scare and not as an inducement to any use. For a person working with this reagent, this is an important reference point when interpreting comparative data within the SARM class.

Safety profile of Andarine (S4) – what has been reported in the literature

The following points describe signals reported in the literature regarding the SARM class and S4 itself. They are not a description of the product’s operation or information about its use – Andarine (S4) is a research reagent and is not intended for consumption.

• Suppression of the hypothalamic-pituitary-gonadal axis. Androgen receptor ligands act on feedback to regulate gonadotropin secretion. Decreased concentrations of luteinizing hormone, follicle-stimulating hormone, and testosterone have been reported in the classroom literature – an effect that challenges the marketing narrative of “no hormonal effect” (Solomon et al., 2019; Bond et al., 2025).
• Decrease in HDL cholesterol. Reducing the HDL fraction is one of the most frequently repeated signals in the entire SARM class. It was reported both in clinical trials of other compounds of this group and in analyzes of adverse events.
• Visual disturbances. Described above: xantopsia and impaired night vision – a signal characteristic of S4, much less frequently reported for other compounds of this class.
• Class adverse events. Leciejewska et al. (2024) compile reports regarding compounds from the SARM group, including: liver signals (elevated enzyme parameters, case reports of drug-induced liver damage), lipid disorders and hormonal axis disorders. The authors emphasize the discrepancy between the image promoted in informal circulation and the actual characteristics of the reports.
• No long-term data. Bond et al. (2025) indicate that for any compound of this class – and especially for Andarine (S4) – we do not have long-term safety data. The cardiovascular, hepatic and oncological risks with chronic exposure remain unknown.

Methodological conclusion: the safety profile of S4 is insufficiently characterized. There is no reason to treat a relationship as a “softer” alternative to anything.

Andarine (S4) and anti-doping control – WADA S1

Andarine (S4) is on the World Anti-Doping Agency (WADA) Prohibited List of Substances and Methods in category S1 – anabolic agents. The ban is in force both in competition and out of competition, which means that the detection of a compound or its metabolites in an athlete’s sample results in an anti-doping rule violation regardless of the time of sample collection.

SARMs, including S4, are a routine part of control programs. Thevis and Schänzer (2018) describe the detection methodology: the basis is liquid chromatography coupled with mass spectrometry (LC-MS/MS), using methods focused on the parent compound and – importantly – on it metabolites. Because Andarine has a short half-life, much of the analytical work is based on the identification of transformation products (including metabolites resulting from hydrolysis and conjugation), which persist in urine longer than the starting compound and extend the detection window.

Practical consequence for the research community: there is no “safe window” or way to bypass detection. Anti-doping methods are developing towards increasingly lower detection thresholds, and WADA-accredited laboratories also have analytical standards for metabolites. The same analysis is an argument for the reasonableness of Andarine as a reagent: the compound remains necessary as reference material in work on detection methods.

A separate note: the presence of SARMs as contaminants in products available on the market has been a source of unintentional anti-doping rule violations – as discussed below.

Reagent quality – why analytics matter

This is a section worth reading even if you know the rest of the description.

In 2017, in CAVITY work was published Van Wagoner et al., which chemically analyzed products sold online as \”SARMs\”. The results were clearly disturbing and to this day are the most frequently cited argument in discussions about the quality of material in this segment. The tested samples showed that:

• a significant part of the products did not contain the declared substance — the active substance content did not correspond to the label;
• some contained other, unapproved compounds — substances outside the declared composition, including other androgen receptor modulators or compounds with a different mechanism;
• the amount of the substance differed from the declaration — both down and up, with high variability between samples;
• some samples did not contain none substances from the declared class.

Translated into the language of research work: material without analytical confirmation it is worthless as a reagent. It’s impossible to interpret the result of an experiment if you don’t know what exactly was in the vessel. Hence the need for hard analytical documentation.

What does HPLC >=98% mean

High Performance Liquid Chromatography (HPLC) separates the mixture into components and allows you to determine what share the main component has in the material. Declaration purity ≥ 98% means that the peak corresponding to the target substance constitutes at least 98% of the total signal – the remaining up to 2% are process impurities, synthesis residues or degradation products. So HPLC answers the question “How many”.

Why mass spectrometry (MS)

HPLC itself does not say what there is a separated component. He answers this mass spectrometry: the method measures the mass-to-charge ratio of ions and allows you to confirm that the molecular weight and fragmentation pattern correspond to the expected structure (for Andarine – C₁₉H₁₈F₃N₃O₆, ~441.4 g/mol). MS answers the question “What”. Only the combination of both methods – identity plus purity – gives a reasonable characterization of the material.

What the COA contains and how to read it

Certificate of Analysis (COA) is a document assigned to a specific one batch material. It is worth paying attention to:

• batch number — must correspond to the marking on the packaging; COA without party affiliation means nothing;
• date of analysis — a document from years ago describes a different series of material;
• HPLC result — with a stated numerical purity value, not the mere statement “compliant”;
• MS confirmation — with a spectrum or at least with an indication of the measured mass;
• name and identifiers of the substance — common name, code, CAS number;
• laboratory performing the analysis — an anonymous document is a worthless document.

Lot traceability

Traceability (batch traceability) means that each unit of material can be associated with a specific production series and the corresponding analytical documentation. This is the foundation of repeatability: without assigning the experimental result to a specific batch, it is impossible to reproduce the study or explain discrepancies between data series.

Each batch of Andarine (S4) supplied by One-Peptides as a research reagent is subject to these standards: HPLC >=98%, confirmation of MS’s identity, COA per batch, full traceability of the series and store in a dry and cool place, away from light and moisture, in the original packaging.

Andarine (S4) in capsule form – what does it mean?

The reagent is supplied in capsule form. The capsule is exclusively form of packaging research material: portioning into repeatable units facilitates batch registration, limits contact with bulk material and simplifies analytical and storage work.

This must be said directly, because it can be a source of misunderstanding: character is not a regulatory class. The capsule is a unit package, not a declaration of purpose. Substances in capsules may be supplements, drugs, reagents or reference materials – the classification is determined by them status of the substance and its purpose, not the shape of the container in which it reaches the recipient.

The capsule form does not change the status of the reagent. Packaging into capsules is a technical solution, not a suggestion of intended use. Andarine (S4) remains a Research Use Only chemical reagent it is not intended for consumption by humans or animals.

The substance content in the unit and its purity are confirmed by the batch analytical documentation (COA). The material is stored in its original packaging, in a dry and cool place, away from light and moisture; capsule form does not require a cold chain. Work with the reagent should be carried out in accordance with the internal procedures of the research unit and be carried out by qualified personnel.

Regulatory status of Andarine (S4)

• Research Use Only (RUO) — reagent intended only for laboratory tests. It is not a medicinal product, dietary supplement or food. It is not intended for consumption.
• No registration as a medicinal product – neither with the European Medicines Agency (EMA), nor with the US FDA, nor with any other agency. The compound has not passed the registration route and has no approved indication.
• WADA: category S1 (anabolic agents) — a substance prohibited in sport, in competition and out of competition.

The trade and possession of compounds of this class are regulated by the regulations applicable to a given country; responsibility for compliance with the law of the destination rests with the recipient. The material is intended only for research applications carried out by qualified personnel.

FAQ – Andarine (S4)

Are Andarine and S4 the same compound?
Yes. Andarine is the common name and S4, S-4 and GTx-007 are the laboratory codes for the same non-steroidal SARM from the arylpropionamide class (CAS 401900-40-1).

Is Andarine (S4) a drug or dietary supplement?
NO. This chemical reagent is intended exclusively for laboratory tests (RUO). It is not a medicinal product, dietary supplement or food and is not intended for consumption.

Where do the reports of yellow vision come from?
Xanthopsia (yellowish tint to vision) and decreased night vision have been reported in the literature and reports. The mechanistic hypothesis associates the phenomenon with the compound’s affinity for receptors present in the retina and with its impact on visual signal processing, primarily in terms of rod function.

Are vision disorders reversible?
In available reports, the effect is described as reversible – disappearing after cessation of exposure. However, these data are mainly self-reported and of limited evidentiary value (Joshi et al., 2025).

How does Andarine (S4) differ from an anabolic steroid?
Construction. Steroids have a steroid core, arylpropionamides do not. Consequently, non-steroidal compounds are not substrates of 5α-reductase or aromatase – they do not produce DHT or estradiol (Narayanan et al., 2018; Solomon et al., 2019). However, the chemical difference does not mean there are no safety signals.

What is the evidence base for Andarine (S4)?
Mostly preclinical. Rodent models are the basis: Gao et al. (2005) – orchidectomized rats; Kearbey et al. (2007) — ovariectomized rats.

Are there studies of Andarine (S4) in humans?
There are no advanced phase III clinical trials. Human data are limited to scattered observations, toxicological analyzes and self-reports. This distinguishes S4 from enobosarm (ostarine), which has undergone much further clinical development.

Is Andarine (S4) allowed in sports?
NO. WADA classifies the compound in category S1 (anabolic agents) – a substance prohibited in competition and out of competition. Detection is carried out using LC-MS/MS methods, also based on metabolites (Thevis and Schänzer, 2018).

Why are HPLC and COA so important?
Because an analysis of products sold online as \”SARMs\” showed that a significant part of them did not contain the declared substance, and some contained other, unapproved compounds (Van Wagoner et al., 2017). Without confirmation of identity (MS) and purity (HPLC), the material is not suitable for use as a reagent.

Does a capsule mean it’s a supplement?
NO. The form is not a regulatory class – the capsule is only a form of packaging. Andarine (S4) remains a RUO research reagent, not intended for consumption.

How to store the reagent?
In the original packaging, in a dry and cool place, away from light and moisture – in accordance with the batch documentation and internal procedures of the research facility. The capsule form does not require a cold chain.

How does Andarine (S4) differ from ostarine (enobosarm)?
First of all, the depth of the evidence base: ostarine underwent clinical trials, S4 remained a mainly preclinical compound. The second difference is the visual signal characteristic of S4 (xanthopsia, worse night vision), rarely reported for other compounds of the class. Both have WADA Prohibited Substance status and both remain research reagents.

More in the knowledge base: the Andarine (S4) category and a profile article on Andarine (S4).

Scientific sources

1. Gao W et al. (2005). Selective androgen receptor modulator treatment improves muscle strength and body composition and prevents bone loss in orchidectomy rats
2. Kearbey JD et al (2007). Selective Androgen Receptor Modulator (SARM) treatment prevents bone loss and reduces body fat in ovariectomized rats
3. Solomon ZJ et al. (2019). Selective Androgen Receptor Modulators: Current Knowledge and Clinical Applications
4. Narayanan R, Coss CC, Dalton JT (2018). Development of selective androgen receptor modulators (SARMs)
5. Bond P et al (2025). Selective androgen receptor modulators: a critical appraisal
6. Leciejewska N et al. (2024). Selective androgen receptor modulators: adverse events
7. Thevis M, Schänzer W (2018). Detection of SARMs in doping control analysis
8. Van Wagoner RM et al. (2017). Chemical Composition and Labeling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet
9. Joshi A et al (2025). Self-Reported Side Effects Associated With Selective Androgen Receptor Modulators: Social Media Data Analysis

SHORT DESCRIPTION (short field – description of the WP product, NOT for body): Andarine (S4, GTx-007) – non-steroidal SARM from the arylpropionamide class, research reagent in capsule form. HPLC purity ≥98%, MS identity confirmation, COA for each batch. Data in the literature are mainly from rodent models; a recognizable element of the S4 profile is the reported, reversible visual disturbances (xantopsia). WADA: category S1. Research Use Only – not for consumption. CAS 401900-40-1.