OPK-88004 | This SARM increases free testosterone levels
American researchers are experimenting with a new SARM that has no impact on the prostate, increases muscle mass, decreases fat mass and also increases the amount of free testosterone. Let's update you on OPK-88004.

Researchers from Brigham and Women's Hospital in Boston, USA, experimented with 114 men who had had a prostatectomy after doctors had detected a non-metastatic form of prostate cancer. The researchers divided the men into 4 groups, and gave them a capsule containing 0 [the placebo group], 1, 5 or 15 milligrams of OPK-88004 every day for 12 weeks.

OPK-88004 was developed by the pharmaceutical company Transition Therapeutics. In 2016 OPKO bought Health Transition Therapeutics.
OPK-88004 increased the lean body mass - let's say: the muscle mass - and reduced the fat mass. The highest dose tested of 15 milligrams per day produced the best results.

The 15 milligram dose also seemed to improve performance on the stair climber and leg press, but the increase was not statistically significant.
Click on the table below for a larger version.

OPK-88004 did not increase PSA levels. This means that the SARM did not stimulate the growth of any prostate cancer cells present. Remarkably, OPK-88004 lowered the total testosterone level and the estradiol level, but actually increased the free testosterone level.
Click on the table for a larger version.

OPK-88004 also had no prosexual effects. For this reason, and because the effects of the new SARM on strength and physical performance were disappointing, the researchers have their doubts about OPK-88004's market potential.
"The administration of a SARM in androgen-deficient men who had undergone radical prostatectomy for low-grade organ-confined prostate cancer was safe and not associated with PSA recurrence", write the researchers.

"OPK-88004 increased lean body mass and decreased fat mass but did not improve sexual symptoms or physical performance."
"The short-term safety data are reassuring and provide the rationale for investigating the efficacy of SARMs, such as the OPK-88004, that were developed for their preferential muscle and bone anabolic effects, among prostate cancer survivors with physical dysfunction, and for developing novel SARMs that preferentially improve sexual function."
J Clin Endocrinol Metab. 2021 Jul 13;106(8):2171-86.