SARMs can selectively navigate to muscles and bones. They activate androgen receptors but are chemically different from steroids. As such,they are not substrates for 5 alpha-reductase or CYP19 aromatase, which prevents their conversion to the testosterone metabolite DHT or estrogen.
In one small, early clinical trial, LGD 4033 increased lean body mass and strength, decreased body fat, improved wellbeing, and enhanced the healing process. However, the doses and goals of clinical studies differ from its real-world use
To rewind to the early research phases, both MK-2866 and LGD-4033 were developed with the goal of reducing muscle wasting in people with muscular dystrophy, the elderly, and in cancer patients.
Realizing that these drugs may also increase bone strength and healing, scientists began looking into their potential to improve bone diseases such as osteoporosis.
LGD 4033 was initially created by Ligand Pharmaceuticals, hence the name “Ligandrol”. Viking Therapeutics took over LGD 4033 research in the meantime, renaming it to VK5211. This small pharma company is researching LGD 4033/VK5211 for hip fracture recovery. They state that it aims to produce all the benefits of testosterone with improved safety.
According to their proponents, SARMs may target the same anabolic pathways as typical steroids but without the androgenic side-effects.
One clinical trial with LGD 4033 involved 76 healthy men, who all received escalating low doses (0.1, 0.3, and 1 mg/day). LGD 4033 was well tolerated and safe over 3 weeks and 1 mg/day (10% of the recommended dose) was sufficient to increase lean body mass by almost 3 lbs. LGD 4033 also increased leg press strength and stair climb power.
The study also revealed other attractive PK attributes of the drug—including a prolonged circulating half-life, dose-proportional systemic exposure, and robust relationships between the dose and outcomes.
An earlier study previously demonstrated the safety of doses up to 22 mg/day. The lower doses in the larger study, however, were estimated to maximize lean muscle gains while minimizing side effects. Note that this data came from animal studies, the purpose of which was to determine the appropriate dose for future clinical trials. Such animal studies don’t reflect the safety or effectiveness of ligandrol in humans.