GSK2881078 is an experimental, nonsteroidal selective androgen receptor modulator (SARM) developed by GlaxoSmithKline (GSK). It was designed to build muscle in people with muscle weakness from chronic and acute illness, while sparing tissues such as the prostate. It is taken by mouth.
It reached phase 2a: a 13-week trial in people with chronic obstructive pulmonary disease (COPD) that finished in 2019. GSK2881078 has never been approved as a medicine anywhere. It is one of the few SARMs with controlled human data on lean mass, but that evidence comes from three small studies totaling about 300 people. Its most unusual feature is a half-life of roughly a week, far longer than other SARMs that have been tested in people.
This page summarizes what the published clinical trials and anti-doping research report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Drug class | Nonsteroidal SARM (indole derivative) |
| Developer | GlaxoSmithKline; investigational code only, no brand name |
| Route | Oral |
| Doses studied in humans | 0.05–0.75 mg/day (first-in-human study); 1 mg/day (women) and 2 mg/day (men) in the COPD trial |
| Half-life | About 103–127 h after a single dose (geometric means), described as about 7.5 days |
| Development stage | Phase 1 and phase 2a trials completed (last finished November 2019); never approved |
| US status | Not FDA approved; not named in the DEA Schedule III list |
| WADA status | Prohibited at all times under S1.2 (SARMs) |
What it is
GSK2881078 is a small synthetic molecule, not a steroid. Its chemical name is 1-[(2R)-1-methylsulfonylpropan-2-yl]-4-(trifluoromethyl)indole-5-carbonitrile, formula C₁₄H₁₃F₃N₂O₂S, molecular weight 330.33 g/mol (PubChem). Doping-control chemists group it with the indole-based SARMs (Stacchini et al., J Pharm Biomed Anal 2021).
Like other SARMs, it binds the androgen receptor, the same receptor testosterone acts on. The aim of the SARM class is to switch the receptor on strongly in muscle and bone and weakly in reproductive tissue. According to GSK’s first human study (Clark et al., Br J Clin Pharmacol 2017):
- it is more than 100-fold selective for the androgen receptor over the glucocorticoid, mineralocorticoid and progesterone receptors;
- in castrated rats, 0.3 mg/kg/day for 28 days restored the weight of the levator ani muscle to normal but only slightly increased prostate weight (company data on file, not published in full).
In cell culture, GSK2881078 activated the androgen receptor at low nanomolar concentrations in a prostate cancer cell reporter assay, and much more weakly in a yeast-based assay (Zierau et al., J Steroid Biochem Mol Biol 2019). These laboratory and animal findings do not show that the drug is tissue-selective in people.
The library has separate pages for other SARMs with human trial data, including ostarine (enobosarm) and ligandrol (LGD-4033).
Pharmacokinetics
The first-in-human study gave single and repeated doses to healthy young men and postmenopausal women (Clark et al. 2017). Single-dose results:
| Single dose | n | Peak level (Cmax, geometric mean) | Half-life (geometric mean) | Time to peak (median) |
|---|---|---|---|---|
| 0.05 mg | 7 | 1.1 ng/mL | 116 h | 1.0 h |
| 0.1 mg | 5 (2 for half-life) | 1.7 ng/mL | 103 h | 1.0 h |
| 0.2 mg | 7 (6 for half-life) | 3.5 ng/mL | 127 h | 1.0 h |
Other findings from the same study:
- Fast absorption, slow elimination. It peaked 1–2 hours after a dose but had a terminal half-life that the authors put at about 7.5 days. They noted this is much longer than enobosarm (about 22 h) or LGD-4033 (24–36 h).
- Loading doses. Because of the long half-life, the repeat-dose cohorts took the drug twice daily for 3 days and then once daily, to reach steady exposure faster. Later GSK trials used the same pattern.
- Food. Taking it with a meal did not change total exposure (AUC) but lowered the peak level by 21%.
- Excretion. Less than 2% of a dose left the body unchanged in urine.
- Exposure rose in proportion to dose in the range tested.
In the 13-week COPD trial, trough levels kept rising through day 28 and reached steady state at about day 56 (Mohan et al., Thorax 2023). A phase 1b study also tested a strong CYP3A4 inhibitor and reported that the effect on GSK2881078 levels was unlikely to be clinically significant (Neil et al., JCEM 2018).
Development status
ClinicalTrials.gov lists three GSK2881078 studies, all completed (ClinicalTrials.gov):
| Study | Phase | Population | Enrolled | Completed |
|---|---|---|---|---|
| NCT02045940 | 1 | Healthy men and postmenopausal women | 99 | March 2015 |
| NCT02567773 | 1 | Healthy older men and postmenopausal women; CYP3A4 interaction cohort | 108 | December 2016 |
| NCT03359473 | 2a | Men and postmenopausal women with COPD and muscle weakness | 97 | November 2019 |
No later trials are registered, and the compound has not been approved in any country. There are no approved indications and no labeled dose.
What the research shows
Healthy older adults (phase 1b)
This randomized, placebo-controlled dose-escalation study enrolled healthy older men and postmenopausal women (Neil et al., JCEM 2018). Doses started twice daily for 3 days, then continued once daily for up to 53 more days, with lean mass measured by DXA and thigh MRI. The authors reported that:
- every dose level produced more lean mass gain than placebo;
- the gain increased with dose;
- women responded at lower doses than men;
- there were no serious adverse events, but alanine aminotransferase (ALT, a liver enzyme) rose transiently.
The full paper was not accessible to us, so we do not report its lean mass figures. A 2023 systematic review that tabulated the trial lists doses of up to 4 mg/day in men for 56 days and 62 people exposed to the drug (Vignali et al., J Xenobiot 2023).
COPD with muscle weakness (phase 2a)
This was the only patient trial. It randomized 97 people with moderate to severe COPD and poor leg function (47 postmenopausal women and 50 men) to GSK2881078 or placebo once daily for 13 weeks (Mohan et al., Thorax 2023). Women took 1 mg and men 2 mg. Everyone also did a home exercise program with strength training. The primary outcome was leg strength (one-repetition maximum, 1RM) at day 90.
Differences between GSK2881078 and placebo at day 90 (90% confidence intervals, as reported):
| Outcome | Women (1 mg) | Men (2 mg) |
|---|---|---|
| Leg strength, kg | +8.0 kg (90% CI −2.5 to 18.4) | +11.8 kg (90% CI −0.5 to 24.0) |
| Leg strength, % change | +5.2% (90% CI −4.7 to 15.0) | +7.0% (90% CI 0.5 to 13.6) |
| Total lean body mass | +2.1 kg (90% CI 1.3 to 3.0) | +2.1 kg (90% CI 1.0 to 3.3) |
| Short physical performance battery score | +0.2 (90% CI −0.4 to 0.9) | +0.1 (90% CI −0.5 to 0.6) |
What this shows:
- Lean mass rose clearly in both sexes, by about 2 kg more than exercise alone.
- Strength gains were small and uncertain. Only the percentage change in men excluded zero, and the trial used 90% rather than the usual 95% intervals.
- Function did not improve. There was no meaningful difference in physical performance scores, gait speed, shuttle walking tests, daily step counts or patient-reported outcomes.
- No link between muscle and strength. Individual gains in lean mass did not track gains in leg strength.
Six weeks after stopping (day 132), mean lean mass was still slightly above baseline in the drug groups: +1.2 kg in women and +0.8 kg in men, versus −0.9 kg and −0.6 kg on placebo (unadjusted means).
Side effects and risks
No trial has tested GSK2881078 for longer than 13 weeks, so long-term safety is unknown. Across the published studies, the main drug-related findings were lower HDL cholesterol, liver enzyme rises and suppression of binding proteins and total testosterone.
Liver enzymes
- First-in-human study. One woman developed a drug rash with ALT 2.9 times the upper limit of normal and was withdrawn; another woman had ALT 2.3 times normal (Clark et al. 2017).
- Older-adult study. According to the 2023 systematic review, ALT rose in 62.9% of people on the drug versus 13.3% on placebo. The rises were most frequent at 4 mg, two people reached 5–10 times normal, and levels returned to baseline (Vignali et al. 2023).
- COPD trial. Two people on the drug (one man, one woman) had ALT about 7 times normal and were withdrawn at days 67 and 28. Both had no symptoms, normal bilirubin, and recovered after stopping (Mohan et al. 2023).
The same review counted 15 case reports of drug-induced liver injury in people using SARMs outside trials. It noted that those users generally took 4–10 times trial doses, often together with other drugs (Vignali et al. 2023). None of those cases named GSK2881078.
Cholesterol
HDL (“good”) cholesterol fell with dose. After 14 days in the first-in-human study, compared with placebo (Clark et al. 2017):
| Group | HDL change vs placebo |
|---|---|
| Men, 0.08 mg/day | −0.165 mmol/L (≈ −6 mg/dL) |
| Men, 0.24 mg/day | −0.265 mmol/L (≈ −10 mg/dL) |
| Men, 0.48 mg/day | −0.357 mmol/L (≈ −14 mg/dL) |
| Women, 0.35 mg/day | −0.518 mmol/L (≈ −20 mg/dL), 95% CI −0.703 to −0.334 |
ApoA1, triglycerides and VLDL also fell; LDL and total cholesterol did not change in that study. In the COPD trial, HDL fell in both sexes, LDL rose mostly in women, and both changes reversed after stopping.
Hormones
“Selective” did not mean free of hormonal effects. In men given 0.08–0.75 mg/day for 14 days (Clark et al. 2017):
- Total testosterone fell by 5.6–7.2 nmol/L more than placebo (≈ 160–210 ng/dL), with no clear dose response. At the two highest doses it stayed low for 14 days after the last dose and was returning to baseline by day 42.
- SHBG (sex hormone-binding globulin, the protein that carries testosterone in blood) fell with dose, by up to 19.6 nmol/L, and had not fully recovered by day 42 at most doses.
- DHT and FSH also fell. LH and calculated free testosterone did not change.
The authors read this as an effect on the liver’s production of binding proteins rather than suppression of the brain’s signals to the testes. That study lasted only 14 days at doses well below those used later. In postmenopausal women, SHBG fell by up to 39 nmol/L at 0.35 mg/day, with no other meaningful hormone changes. Thyroxine-binding globulin also fell in both sexes.
Other events
- Creatine kinase. In the first-in-human study, two men developed very high creatine kinase (17,841 and 4,590 IU/L) with muscle soreness after hard exercise, 14 and 28 days after their last dose. The values resolved within 3 weeks, and investigators judged them not drug-related (Clark et al. 2017). A later review described these as rhabdomyolysis (muscle breakdown) and said the link to the drug is uncertain (Vignali et al. 2023).
- COPD trial. Withdrawals for adverse events occurred in 2 of 24 women and 4 of 25 men on the drug, versus 0 of 23 women and 5 of 24 men on placebo. No serious adverse event was judged drug-related. One woman on the drug developed acne; hematocrit and mean PSA did not change meaningfully (Mohan et al. 2023).
- Virilization in women. No trial in women ran longer than 13 weeks, so whether the drug causes lasting masculinizing effects is unknown.
Legal status and detection in sport
GSK2881078 has no medical approval in any country. It is not named in the US Schedule III list of anabolic steroids (21 CFR 1308.13). Any product sold under this name comes from outside the regulated drug supply.
The WADA 2026 Prohibited List bans SARMs at all times, in and out of competition, under S1.2 “Other anabolic agents” (WADA 2026 Prohibited List). GSK2881078 is not named, but the list covers the class “including but not limited to” its examples.
Because of its long half-life, the drug stays detectable for a long time. After a single oral dose of 760 μg, urine levels peaked at about 920 pg/mL after 8 hours and only fell to the detection limit (2 pg/mL) on day 42. After a single 1.5 mg dose, the intact drug was also found in hair from the matching growth period (Rading et al., Drug Test Anal 2021). Anti-doping labs have published screening methods that include GSK2881078 and its metabolites (Stacchini et al. 2021).
Key takeaways
- An experimental drug, never approved. GSK tested it in three studies, the last a phase 2a COPD trial that finished in 2019; no later trials are registered.
- Very long half-life. About 4–5 days after single doses, which GSK described as about 7.5 days, much longer than other tested SARMs. Trials used a 3-day twice-daily loading phase.
- Lean mass, but no proven function benefit. In COPD, 1–2 mg/day added about 2.1 kg of lean mass over 13 weeks. Strength gains were small and uncertain, and physical function did not improve.
- Women were more sensitive. They had larger lipid and SHBG changes at lower doses, and later trials gave women half the men’s dose.
- Class side effects appeared at low doses. HDL fell, ALT rose (up to about 7 times normal in the COPD trial), and total testosterone fell in men within 14 days.
- Banned in sport and detectable for weeks. WADA prohibits all SARMs at all times, and after a single 760 μg dose, urine levels took 6 weeks to fall to the detection limit.
Sources
- Clark RV, Walker AC, Andrews S, Turnbull P, Wald JA, Magee MH. Safety, pharmacokinetics and pharmacological effects of the selective androgen receptor modulator, GSK2881078, in healthy men and postmenopausal women. Br J Clin Pharmacol. 2017;83(10):2179–2194. PubMed.
- Neil D, Clark RV, Magee M, Billiard J, Chan A, Xue Z, Russell A. GSK2881078, a SARM, produces dose-dependent increases in lean mass in healthy older men and women. J Clin Endocrinol Metab. 2018;103(9):3215–3224. PubMed.
- Mohan D, Rossiter H, Watz H, et al. Selective androgen receptor modulation for muscle weakness in chronic obstructive pulmonary disease: a randomised control trial. Thorax. 2023;78(3):258–266. PubMed.
- Vignali JD, Pak KC, Beverley HR, et al. Systematic review of safety of selective androgen receptor modulators in healthy adults: implications for recreational users. J Xenobiot. 2023;13(2):218–236. PubMed.
- Zierau O, Kolodziejczyk A, Vollmer G, et al. Comparison of the three SARMs RAD-140, GLPG0492 and GSK-2881078 in two different in vitro bioassays, and in an in silico androgen receptor binding assay. J Steroid Biochem Mol Biol. 2019;189:81–86. PubMed.
- Rading A, Anielski P, Thieme D, Keiler AM. Detection of the selective androgen receptor modulator GSK2881078 and metabolites in urine and hair after single oral administration. Drug Test Anal. 2021;13(1):217–222. PubMed.
- Stacchini C, Botrè F, Comunità F, et al. Simultaneous detection of different chemical classes of selective androgen receptor modulators in urine by liquid chromatography-mass spectrometry-based techniques. J Pharm Biomed Anal. 2021;195:113849. PubMed.
- National Center for Biotechnology Information. GSK2881078, PubChem CID 86709174. PubChem.
- ClinicalTrials.gov. Studies of GSK2881078: NCT02045940, NCT02567773, NCT03359473. ClinicalTrials.gov; NCT02045940; NCT02567773; NCT03359473.
- World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. WADA 2026 Prohibited List.
- Code of Federal Regulations. Title 21, Section 1308.13: Schedule III. 21 CFR 1308.13.