Cardarine + Ostarine MK-2866 stack

iMuscle Cardarine + Ostarine MK-2866 is a two-compound bundle from iMuscle that pairs Cardarine (GW-501516) with Ostarine (MK-2866), 60 capsules in total. iMuscle does not state the strength of either compound and we do not guess at it. The bundle is a pricing convenience for buying both in one listing; we make no claim that the two do anything together. Supplied for laboratory research only, not for human consumption, to adults aged 18 and over.

About the compounds in this bundle

Cardarine (GW-501516)

Cardarine, also written GW501516 or endurobol, is a synthetic PPAR-delta agonist developed by GlaxoSmithKline and Ligand for lipid disorders; it is not a SARM. A 2012 twelve-week human trial in subjects with low HDL cholesterol recorded a rise in HDL and a fall in triglycerides, but was not designed to assess long-term safety (Olson et al., 2012). Clinical development was halted after two-year rodent carcinogenicity studies found tumours in multiple organs. Every brand we stock is on the Cardarine collection page, and the history is told in cardarine: what happened in development.

Ostarine (MK-2866)

Ostarine, also called MK-2866 or enobosarm, is a non-steroidal selective androgen receptor modulator developed by GTx for muscle wasting and the most clinically studied SARM. In a 2011 placebo-controlled Phase 2 trial in 120 healthy elderly men and postmenopausal women, lean body mass rose by an average of 1.3 kg more than placebo over twelve weeks at the highest dose studied. HDL cholesterol fell in a dose-dependent way, eight participants had transient rises in the liver enzyme ALT, and one was withdrawn for this reason (Dalton et al., 2011). Later Phase 3 trials in people with cancer-related muscle loss did not lead to approval. See the Ostarine collection page and the ostarine research guide.

Nothing summarised above is a claim about this product, and we know of no published study that has examined these compounds together.

This listing

• Brand: iMuscle
• Compounds: Cardarine (GW-501516) and Ostarine (MK-2866)
• Form: capsules
• Pack size: 60 capsules in total across the bundle
• Strength per compound: not stated by the manufacturer
• Bundle basis: pricing convenience only; no combined effect is claimed
• Use: laboratory research only, not for human consumption, adults 18 and over

With no stated strength, total milligrams per pack cannot be calculated and we do not estimate it. The single-compound listings, iMuscle Cardarine GW-501516 and iMuscle Ostarine MK-2866, carry a label strength; see price per milligram for how to compare them.

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

Searches such as "cardarine UK legal", "MK 2866 buy UK" and "cardarine UK reviews" ask two things: is the purchase lawful, and will the seller send what the label says.

The legal position

This bundle contains Cardarine and Ostarine. Neither is a licensed medicine in the UK (MHRA) or an authorised food supplement. They are not controlled drugs and may be sold to adults for laboratory research, the only basis for this listing. Selling either with directions for human use, or with promises of physical results, could bring the product within the legal definition of a medicine, which is why this page gives neither. Both are on the WADA Prohibited List, Cardarine under S4 (hormone and metabolic modulators) and Ostarine under S1 (anabolic agents), and are banned in tested sport at all times. The class is introduced in What are SARMs? The 2026 research guide, although only ostarine belongs to it.

Signs of a listing that can be checked

1. A manufacturer and a seller you can name. Here the maker is iMuscle and the seller is FreeMuscle LTD, a UK company based in Scunthorpe.
2. A batch number on every pot. Without one, no document can be matched to what arrived.
3. A certificate for that batch, not a sample PDF. For iMuscle we show one only where the manufacturer supplies it for the batch we hold.
4. A stated strength. This is where the bundle falls short, because iMuscle does not state one; we say so rather than fill the gap.
5. No usage directions or result claims. A listing that offers them is not selling for research.
6. Plain, tracked delivery and a returns route. Every UK order ships free and tracked in plain packaging; orders placed before 2pm Monday to Friday are processed the same working day; EU delivery takes 3-7 working days; unopened items can be returned within 30 days. Details are on the shipping and guarantee pages.

Reviews describe delivery and service; only a laboratory analysis of the lot can confirm what a capsule contains. A longer checklist sits in how to choose a SARMs supplier in the UK, and the other brands on this marketplace are introduced on the Muscle Market page.

Capsules compared with other forms

Searches for "ostarine liquid UK", "ostarine tablets UK" and "ostarine capsules UK" show that buyers meet the same molecule in several formats. The format does not alter the chemistry; it alters how the amount in each unit is fixed and how easily a certificate can speak to it.

Both compounds here are small synthetic molecules, not peptides: ostarine has a molecular weight of 389.3 and cardarine 453.5. The digestive breakdown that limits swallowed peptides, covered in do oral peptides work, is therefore not the relevant issue for either. We know of no study comparing retail formats of either compound. A capsule with a declared strength is simply the easiest format to check, and this bundle lacks that declaration.

Ostarine compared with MK-677

"MK 2866 vs MK 677" is one of the most common comparison searches for ostarine, largely because the two codes look alike. The shared "MK" prefix is a development code and says nothing about how the molecules act. They sit in different drug classes, bind different receptors and fall under different sections of the WADA list.

The MK-677 row on adverse findings comes from the 2008 trial by Nass and colleagues, in which 65 healthy adults aged 60 to 81 were randomised to MK-677 or placebo. Growth hormone and IGF-1 rose into the young-adult range and fat-free mass increased by 1.1 kg against a 0.5 kg fall on placebo, but fasting glucose rose, insulin sensitivity fell, cortisol increased, and the gain in fat-free mass was not matched by any change in strength or function (Nass et al., 2008). Set that beside the ostarine trial above and the difference is one of route: ostarine acts at the androgen receptor directly, while MK-677 works upstream by prompting the pituitary to release growth hormone. Neither trial compared the two, and we know of no study that has.

MK-677 brands are listed in the MK-677 collection, its evidence is summarised in MK-677 (ibutamoren): what the research says, and its UK position is set out on the MK-677 legal status page. Cardarine, the other half of this bundle, is often mentioned alongside SR9009, which acts on a different receptor family altogether; see the SR9009 collection and the SR9009 research guide.

Reading the certificate of analysis for this product

iMuscle is a third-party brand, so any certificate of analysis is the manufacturer's. We show one only where iMuscle supplies it for the batch we hold. A bundle may draw on a separate batch per compound, so expect one certificate per compound and ask for each by name. A generic PDF with no batch number is not a batch certificate. Free Muscle-brand batches are assayed by Janoshik Analytical, an independent laboratory, with the certificate sent on request by email; that programme does not cover iMuscle. Our approach is set out on the lab tests page.

Work through each certificate in this order:

1. Match the lot. The batch number on the certificate must be the one printed on the pot in front of you. If they differ, the document describes other capsules.
2. Check the identity method. HPLC compared against a reference standard, or LC-MS giving a mass consistent with the formula. For ostarine that is C19H14F3N3O3 (CAS 841205-47-8); for cardarine C21H18F3NO3S2 (CAS 317318-70-0). Ostarine has one stereocentre and the active form is (2S), which a mass alone cannot distinguish from its mirror image; cardarine has no stereocentre.
3. Treat purity as purity. A figure such as 99% describes how clean the detected material is, measured by peak area on a chromatogram. It is silent on how many milligrams sit in each capsule.
4. Look for a content figure. A measured amount per capsule is the field that would matter most here, because there is no label strength to check it against.
5. Who tested it, and when. An unnamed laboratory cannot be asked to confirm a report, and an old test date says nothing about storage since.

Where a field is absent, the certificate has simply not answered that question. Send the product name and both batch numbers through our contact page and we will say what paperwork iMuscle has provided. Further detail is in how to read a certificate of analysis.

Detection, sport and testing

Both compounds are prohibited in and out of competition. Ostarine is listed in section S1 of the WADA Prohibited List as an anabolic agent and cardarine in section S4 among hormone and metabolic modulators. Anti-doping rules work on strict liability: a prohibited substance in a sample is the athlete's responsibility, whatever route it took, including a contaminated or mislabelled product.

For ostarine, sensitivity is well documented. Researchers at the German Sport University Cologne gave volunteers single and repeated oral amounts of 1, 10 and 50 micrograms, chosen to model supplement contamination rather than deliberate use, and analysed urine by LC-MS/MS (Walpurgis et al., 2020). A single 1 microgram amount could still be found for up to nine days when ostarine was targeted, and up to five days for its glucuronide. Detection times lengthened as the amount rose, and varied widely between people.

No verified study we can cite gives a window after milligram amounts of ostarine, or any urinary window for cardarine after capsules of unstated strength. For both compounds in this bundle the accurate statement is: detectable, window not established. Anyone subject to an anti-doping code should regard any contact with either as a risk of an adverse finding.

Storage, stability and handling

No published shelf-life study of ostarine or cardarine capsules is available to cite, so we quote no shelf life and rely on the expiry date iMuscle prints on each pot.

• One compound, one pot. Keep cardarine and ostarine in their own original containers. Capsules from a bundle can look alike, and once decanted or mixed they cannot be traced back to a batch number or a certificate.
• Temperature and light. A cool cupboard away from heaters, ovens and direct sunlight.
• Moisture. Replace the lid straight after opening and leave any desiccant sachet in place. Gelatin and plant-based shells absorb water, which can soften them and let the contents clump.
• Paper trail. Keep a simple log for each pot: compound, batch number, date received, date opened. Any portion set aside for testing gets the same three details on its own label.
• Laboratory practice. Wear gloves for opened capsules, keep food and drink away from the work area, store out of reach of children and pets, and dispose of unwanted material as chemical waste under local rules, not in household bins or drains.

The 30-day return option applies only while a pot is still sealed, so check the batch details against any certificate before opening.

Glossary

• SARM: short for selective androgen receptor modulator. The label fits ostarine in this bundle but not cardarine, which does not act at the androgen receptor.
• PPAR-delta: one of three peroxisome proliferator-activated receptors inside the cell nucleus; cardarine was designed to activate this subtype selectively.
• Ghrelin mimetic: a compound that copies the action of the hormone ghrelin at its receptor, as MK-677 does.
• Carcinogenicity study: a regulatory toxicology test in which animals receive a substance for most of their lifespan and are examined for tumours; the cardarine findings came from studies of this kind.
• HDL cholesterol: the lipoprotein fraction that rose in the cardarine lipid trial and fell in the ostarine Phase 2 trial.
• Glucuronide: a form of a compound the body links to glucuronic acid for excretion, often a target in urine testing.
• Strict liability: under anti-doping codes, a positive sample is an offence in itself; intent and source affect only the sanction.
• Enantiomer: either of two mirror-image versions of a molecule with one stereocentre. Ostarine has two; cardarine has no mirror-image form.
• Chromatogram: the trace an HPLC run produces; each peak is a separated substance, and the main peak's share of the total area gives the purity figure.

Related

• Cardarine (GW-501516), all brands
• Ostarine (MK-2866), all brands
• MK-677, all brands and all SARMs
• iMuscle brand collection
• All bundles
• Frequently asked questions

Research use only. Not evaluated by the MHRA, EMA or FDA, not a food supplement, not for human consumption. Sold to adults aged 18 and over. Nothing on this page is medical or dosing advice or a suggestion that the compounds be combined; research summaries describe findings in study participants, not claims about this product.

References

1. Olson EJ, et al. Lipid effects of peroxisome proliferator-activated receptor-delta agonist GW501516 in subjects with low high-density lipoprotein cholesterol: characteristics of metabolic syndrome. Arterioscler Thromb Vasc Biol. 2012;32(9):2289-94. PMID: 22814748.
2. 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.
3. Nass R, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med. 2008;149(9):601-11. PMID: 18981485.
4. Walpurgis K, et al. Elimination profiles of microdosed ostarine mimicking contaminated products ingestion. Drug Test Anal. 2020;12(11-12):1570-1580. PMID: 32959982.