I've been researching Pubmed for studies relating to piperine and how it interacts with the AR. Supposedly piperine docks to the androgen receptor and presumably blocks endogenous androgens from imparting their effects. My question is: how long does this happen, and is there a positive rebound effect after the piperine is excreted. The studies don't seem to investigate that outcome.
I've not heard of any athlete reporting a negative impact on their libido or performance from using piperine, yet a study with rats showed it can cause atrophy of sexual organs, albeit the dosages given were probably astronomical.