SARMs are the successors of the good, old anabolic steroids. A number of these, such as RAD140 and LGD4033, have already become established in pharmacological bodybuilding. GlaxoSmithKline (GSK) researchers are researching another SARM, about which they release remarkably little. But what we have learned about GSK2881078 so far suggests that this could be a more-than-average effective muscle builder.
We’ll say it right away
You obviously want to know what effect GSK2881078 has on muscle. So do we. However, the researchers say nothing about it. GSK hasn’t even published animal studies, which at least can give some indication. Maybe GSK wanted to let sleeping dogs lie. And we mean especially the sleeping dogs that sell research chemicals or rogue supplements.
The only thing we could find about the anabolic effect of GSK2881078 is this sentence, hidden in a publication published in 2017 in the British Journal of Clinical Pharmacology:
“GSK2881078 at 0.3 mg/kg/d dosed orally once daily for 28 days restored the weight of the levator ani muscle in orchiectomized rats to that of sham-operated rats but produced only a minor increase in prostate weight compared with vehicle-treated orchiectomized rats (unpublished data on file, GlaxoSmithKline, 709 Swedeland Road, King of Prussia, PA, USA 19406).”
The study in the British Journal of Clinical Pharmacology is a Phase-1 trial. Phase-1 trials are intended to determine how a new drug should be administered, at what doses, and what side effects it may have.
The researchers gave GSK2881078 in doses of 0.05, 0.08, 0.24, 0.48 and 0.75 milligrams per day to adult men, and in doses of 0.24 and 0.35 milligrams to postmenopausal women for up to 14 days. The mode of administration was, as in the animal study we mentioned above, oral.
The half-life of GSK2881078 is 4-5 days. That’s long. As a result, GSK2881078 could be a pretty effective muscle enhancer.
The detection of GSK2881078 through doping tests will be a piece of cake. Fifty days after taking the last pill, the researchers could still find the drug in the blood of the test subjects.
The doses tested reduced total testosterone levels, but this decrease was mainly due to SHBG-bound – and inactive – testosterone. (GSK2881078 lowered the SHBG level.) In men, the concentration of free testosterone did not decrease.
Click on the figure below for a larger version.
The negative effect of GSK2881078 on cholesterol is considerable. In a period of 14 days the concentration of the ‘good cholesterol’ HDL sometimes dropped by a few dozen percent. A few weeks after stopping use, HDL levels recovered. But still.
In the same edition of the British Journal of Clinical Pharmacology, James Dalton, the researchers who designed the very first SARMs – including Enobosarm/ostarine– gives some comments on GlaxoSmithKline’s research. [Br J Clin Pharmacol. 2017 Oct; 83 (10): 2131-3.]
“Negro-Vilar [J Clin Endocrinol Metab. 1999 Oct;84(10):3459-62.] defined an ideal SARM for the treatment of male hypogonadism as one that is orally active, suitable for once daily administration, and capable of enhancing fat-free mass, muscle mass and strength, bone growth and libido, with lesser but stimulatory effects on the prostate, seminal vesicles and other sex accessory tissues”, Dalton wrote.
“Although it has been 2 decades since the initial discovery of a SARM, much work remains to be done before they can be used for muscle wasting or another condition. GSK2881078 has taken the earliest steps down this winding road.””Like other SARMs ahead of it in development, GSK2881078 appears to meet most of these criteria.”