A 2006 study determined that 1-testosterone has a high androgenic and anabolic potency even without being metabolized, so it can be characterized as a typical anabolic steroid. 1-Testosterone binds in a manner that is highly selective to the androgen receptor (AR) and has a high potency to stimulate AR-dependent transactivation . In vivo , an equimolar dose of 1-testosterone has the same potency to stimulate the growth of the prostate , the seminal vesicles and the androgen-sensitive levator ani muscle as the reference anabolic steroid testosterone propionate , but, unlike testosterone propionate, 1-testosterone also increases liver weight. 
From the lymphatic system testosterone undecanoate is released into the plasma. Single administration of 20-80 mg Restandol Testocaps to postmenopausal women leads to peak-levels of total plasma testosterone of approximately -, - and -/ml after a dose of 20, 40 and 80 mg Restandol Testocaps, respectively . These levels are reached approximately 5-6 h (t max ) after administration. Plasma testosterone levels remain elevated for at least 8 hours. In Japanese women the testosterone levels are about two fold higher.
After the 1 st intramuscular injection of 1000 mg testosterone undecanoate to hypogonadal men, mean Cmax values of 38 nmol/L (11 ng/mL) were obtained after 7 days. The second dose was administered 6 weeks after the 1 st injection and maximum testosterone concentrations of about 50 nmol/L (15 ng/mL) were reached. A constant dosing interval of 10 weeks was maintained during the following 3 administrations and steady-state conditions were achieved between the 3 rd and the 5 th administration. Mean Cmax and Cmin values of testosterone at steady-state were about 37 (11 ng/mL) and 16 nmol/L (5 ng/mL), respectively. The median intra- and inter-individual variability (coefficient of variation, %) of Cmin values was 22 % (range: 9-28%) and 34% (range: 25-48%), respectively.