Ostarine + Andarine + Cardarine stack

The iMuscle Ostarine, Andarine and Cardarine bundle groups three research compounds from one manufacturer into a single listing: ostarine (MK-2866), andarine (S-4) and cardarine (GW-501516). iMuscle lists the pack as 60 capsules and does not state a strength per capsule, so we do not quote one. Supplied to adults for laboratory research only, not for human consumption.

A bundle is a listing convenience only: it lets separately packaged products from one manufacturer be ordered in a single purchase. Nothing on this page claims that they act together or should be studied together, and Free Muscle publishes no stack or cycle guidance for any product.

About the compounds in this bundle

Ostarine (MK-2866, enobosarm)

Ostarine (MK-2866, enobosarm, GTx-024) is a non-steroidal selective androgen receptor modulator developed for muscle wasting, and one of the most clinically studied SARMs. A 2011 phase II trial in healthy older adults reported more lean body mass than placebo over twelve weeks, alongside dose-related falls in HDL cholesterol and, in men, lower SHBG and total testosterone. Phase III cancer cachexia trials reported lean mass gains but missed their physical function endpoints, and it was never approved. WADA class S1. Compare brands on the Ostarine (MK-2866, enobosarm) collection page.

Andarine (S-4)

Andarine (S-4, GTx-007) is an earlier aryl-propionamide SARM from the same programme as ostarine. Its evidence is preclinical: in ovariectomised rats it prevented bone loss and reduced body fat in a 2007 study. No controlled human trial has been published and no regulator has approved it. WADA class S1. Compare brands on the Andarine (S-4) collection page.

Cardarine (GW-501516)

Cardarine (GW-501516, endurobol) is not a SARM but an agonist at the PPAR-delta nuclear receptor, which regulates fatty-acid oxidation genes. In a small two-week 2007 study of 24 healthy volunteers, HDL cholesterol rose relative to placebo and fat clearance after a test meal improved, while fasting triglycerides only trended lower. Development was later discontinued after long-term rodent toxicology studies reportedly found tumours in several organs, a sponsor-reported finding that ended further human work. Never approved; prohibited by WADA as a metabolic modulator under section S4. Compare brands on the Cardarine (GW-501516) collection page.

These summaries describe what was measured in trial participants and laboratory animals. None of it is a claim about the capsules in this bundle.

This listing

• Brand: iMuscle (third-party brand, Muscle Market)
• Compounds: ostarine (MK-2866), andarine (S-4), cardarine (GW-501516)
• Form and pack size: 60 capsules, as listed by the manufacturer
• Strength per capsule: not stated by the manufacturer
• COA: only where iMuscle supplies one for the batch held

Ostarine, andarine and cardarine in the UK: buying, legal status and what to check

Searches such as "ostarine UK buy", "cardarine UK legal" and "andarine UK" reduce to two questions. Can these compounds lawfully change hands in Britain, and how can a buyer tell a checkable listing from one that asks to be taken on trust?

Where the law stands

None of the three appears in the schedules of the Misuse of Drugs Act 1971, so none is a controlled drug. None holds a UK marketing authorisation from the MHRA, so none may be sold or promoted as a medicine, and none is an authorised food supplement or novel food, so none may be sold for eating. What remains is supply as a chemical for laboratory research, to adults, with no directions for use and no promised outcome. That is the only basis on which Free Muscle lists this bundle. In sport the position is stricter: ostarine and andarine are prohibited at all times under WADA section S1, and cardarine under section S4.

Why the listing matters more than the compound name

A 2017 study in JAMA bought 44 products sold online as SARMs and analysed them with methods accredited for anti-doping work (Van Wagoner et al., 2017). Only 23 contained a SARM at all. A further 17 contained another unapproved drug, among them GW501516 and SR9009; four contained no active compound; eleven held something not named on the label; and in just 18 did the measured amount match the label. The lesson for this bundle is direct: the name on a pot is a claim, and only an analysis of the lot tests it.

What a checkable UK listing shows, and where this one stands

This bundle meets the seller-side checks but not the strength check, because the manufacturer has not published one; the single-compound listings in each collection are the alternative where a stated strength matters. Reviews can report delivery times, not what a capsule contains. A fuller checklist is in how to choose a SARMs supplier in the UK, and the class is introduced in What are SARMs? The 2026 research guide.

Capsules compared with other forms

All three compounds are also sold as liquids and loose powders, hence searches such as "ostarine liquid UK". The chemistry does not change with the format; what changes is where the amount per unit is fixed and how it can be checked.

• Capsules. The amount is set when powder is filled into shells, before the container is sealed, so a certificate can report a measured figure per capsule. Its blind spot is variation from one capsule to the next, which a pooled assay averages away.
• Liquids. The label gives a concentration, so every portion depends on the accuracy of a dropper or syringe. Solvent loss from a bottle opened often raises the concentration, and a compound held near its solubility limit can settle out in the cold. A certificate for a liquid describes the bottle only as it was when sampled.
• Loose powder. Nothing is portioned in advance, so accuracy rests entirely on the balance used to weigh it.

None of the three is a peptide. Ostarine (molecular weight 389.3), andarine (441.4) and cardarine (453.5) are small synthetic molecules, so the usual objection to swallowed peptides, breakdown by digestive enzymes, does not apply to them in the same way; the background is in do oral peptides work. No published study compares formats for any of the three, so nothing here suggests one format works better than another. A capsule with a stated strength is simply the easiest format to verify, and this bundle lacks one.

Cardarine compared with SR9009 (stenabolic)

"Stenabolic vs cardarine" is the comparison searched most often for the one non-SARM in this bundle. The two are often mistaken for relatives, but they act on different receptors and have very different evidence behind them.

The practical difference is the depth of the record. Cardarine reached people under trial conditions, so there are measured lipid changes and a documented reason for its abandonment. SR9009 has neither: its reputation as an "exercise mimetic" rests on mouse work, and its oral bioavailability in humans has not been established. No study has compared the two directly. They do meet in two places. The 2017 JAMA analysis found both inside products labelled as SARMs, and both fall under the same WADA section. The development history of cardarine is covered in cardarine: what happened in development; SR9009 brands are listed in the SR9009 collection and explained in the SR9009 research guide.

For the two SARMs in the bundle, the searched comparisons are "andarine vs ostarine" and "ligandrol vs ostarine". The first is set out on the iMuscle Andarine S-4 page and the second on the iMuscle Ostarine MK-2866 page, with LGD-4033 brands in the LGD-4033 collection.

Reading the certificate of analysis for this product

iMuscle is a third-party brand, so any certificate of analysis (COA) for this bundle is the manufacturer's. We display one only where iMuscle supplies it for the exact batch we hold, and we never substitute a generic document. Free Muscle-brand products are assayed batch by batch at Janoshik Analytical, with the certificate emailed on request; that programme does not extend to iMuscle. A bundle raises one extra point: three compounds means three identities to confirm, normally on three certificates, one per lot.

On each certificate, look for these fields:

• Identity. HPLC against a reference standard, or LC-MS giving a mass that fits the formula above. Without it, a purity figure could belong to a different substance.
• Purity. Usually an HPLC peak-area percentage. It shows what share of the detected material is the named compound, not how many milligrams a capsule holds.
• Content per capsule. A measured milligram figure. For this bundle there is no label strength to compare it with, so the certificate would be the first statement of strength rather than a check on one.
• Batch number, test date and laboratory. The lot on the certificate must match the lot on the container, and a named laboratory can be asked to confirm the report is genuine.

If any field is missing, the matching question stays open. Contact us with the lot numbers and we will say what documentation exists. Further detail is in how to read a COA and on our lab tests page.

Detection, sport and testing

All three compounds are on the WADA Prohibited List and banned in and out of competition. Ostarine and andarine sit in section S1.2, other anabolic agents. Cardarine has been on the list since January 2009, first as a gene doping substance and now in section S4 among metabolic modulators (Kintz et al., 2020). Anti-doping rules apply strict liability, so an athlete answers for any prohibited substance found in a sample whatever its source, including a mislabelled product.

Accredited anti-doping laboratories screen urine for all three, and hair analysis can in principle reach further back. In 2020, forensic toxicologists in Strasbourg reported the first identification of GW501516 in human hair, at 32 and 22 pg/mg in two consecutive 2 cm segments from one male user, and noted that this was not expected for a molecule carrying a carboxylic acid group (Kintz et al., 2020).

What no verified study gives is a detection window after capsules like these, whose strength is not even stated. For every compound in this bundle, the accurate position is: detectable, window not established. Anyone bound by an anti-doping code should treat any contact with these compounds as a risk of an adverse finding.

Storage, stability and handling

We can cite no published shelf-life study for ostarine, andarine or cardarine in capsule form, so we quote no shelf life. Work to the expiry date printed on each iMuscle container, and remember that a certificate describes a batch only on its test date.

• Keep the products apart. Leave each compound in its own labelled container. Capsules of different compounds can look alike, and once mixed or decanted they can no longer be matched to a lot number or a certificate.
• Cool, dry and dark. A closed cupboard away from radiators, ovens and sunny windowsills. Close the lid after every opening; capsule shells take up moisture, so bathrooms and kitchens are poor places for them.
• Record as you go. Note each lot number and the date its seal was broken. Label any sample taken for analysis with compound, lot and date.
• Handle as laboratory chemicals. Gloves for opened capsules or powder, no food or drink nearby, out of reach of children and pets, and disposal as chemical waste under local rules rather than in household bins or drains.

Opening a container also ends the 30-day return option, which applies to unopened items only.

Glossary

• SARM: selective androgen receptor modulator, a non-steroidal compound that activates the androgen receptor; ostarine and andarine are SARMs, cardarine is not.
• Aryl-propionamide: the chemical family shared by ostarine and andarine.
• PPAR-delta: peroxisome proliferator-activated receptor delta, the nuclear receptor cardarine binds.
• REV-ERB: a pair of circadian clock receptors targeted by SR9009, unrelated to PPAR-delta.
• Metabolic modulator: the WADA category in section S4 that covers PPAR-delta agonists and AMPK activators.
• Cachexia: the muscle and weight loss that accompanies cancer and other chronic illness, the condition ostarine's phase III trials targeted.
• Stereocentre: an atom that allows two mirror-image forms of a molecule; ostarine and andarine each have one, cardarine has none.
• HPLC and LC-MS: liquid chromatography, alone or linked to mass spectrometry, used to identify a compound and measure its purity.

Related

• Ostarine (MK-2866) collection and the ostarine research guide
• Andarine (S-4) collection
• Cardarine (GW-501516) collection
• SR9009 collection and all SARMs
• iMuscle brand page
• Bundles collection
• Comparing listings by price per milligram

Supplied for laboratory research use only. Not a medicine, not evaluated by the MHRA, EMA or FDA, and not for human consumption. Buyers must be 18 or over. Nothing on this page is medical or dosing advice or a recommendation to use, stack or cycle any compound; research summaries describe findings in study participants or animals, not claims about this product.

References

1. Dalton JT, et al. The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II trial. J Cachexia Sarcopenia Muscle. 2011;2(3):153-161. PMID: 22031847.
2. Kearbey JD, et al. Selective Androgen Receptor Modulator (SARM) treatment prevents bone loss and reduces body fat in ovariectomized rats. Pharm Res. 2007;24(2):328-35. PMID: 17063395.
3. Sprecher DL, et al. Triglyceride:high-density lipoprotein cholesterol effects in healthy subjects administered a peroxisome proliferator activated receptor delta agonist. Arterioscler Thromb Vasc Biol. 2007;27(2):359-65. PMID: 17110604.
4. Van Wagoner RM, et al. Chemical Composition and Labeling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet. JAMA. 2017;318(20):2004-2010. PMID: 29183075.
5. Kintz P, et al. Testing for GW501516 (cardarine) in human hair using LC/MS-MS and confirmation by LC/HRMS. Drug Test Anal. 2020;12(7):980-986. PMID: 32298044.