Testosterone buciclate, a long-acting androgen ester, shows promise as a research agent for male hypogonadism.

Testosterone buciclate (i.m. at four sites, 20 mg/site, on days 1 and 91 of the study period, 360 days) shows reduced testicular volume (days 90-270), suppresses sperm motility and gel penetrability (days 45-240 except on day 120), decreases sperm count (days 75-270), and an increased percentage of spermatozoa showing retention of cytoplasmic droplet and coiled tail (days 45-240 except on day 120)[1].