Review 180:6 R208 as the major treatment of prostate carcinoma, when androgen deprivation therapy (ADT) by GnRH analogues or antiandrogens was introduced instead. Huggins statement Cancer of the prostate is activated by androgen induced a general fear of testosterone, injections especially among urologists, which prevented testosterone treatment in many patients who might have needed it. Only recently it became clear that neither endogenous serum testosterone levels (48) nor testosterone treatment (49) have an impact on prostate carcinogenesis. Nowadays under careful supervision testosterone treatment is even considered for patients suffering from testosterone deficiency after radical prostatectomy and castration (50).

Eventually, at least in Europe, 17-methyl-testosterone became obsolete for clinical use after introduction of orally effective testosterone undecanoate in the late 1970s (see below). As native testosterone proved to be ineffective orally, parenteral routes were explored. Subdermal testosterone pellet implants were the first to be investigated (56) and pellets are still in use today. Their application requires a small operation and harbours the risk of infection and extrusion. However, if enough pellets are implanted, they may provide substitution for up to half a year and are sporadically still used today (51).

Development of testosterone preparations for clinical use (1) Soon after its synthesis it became clear that, in reasonable doses, testosterone was not effective orally or as we know today would require extremely high doses which were simply not available and/or too expensive. Today we know that the lack of oral effectiveness is due to the inactivation of testosterone by the first-pass effects in the liver. Three approaches were used to overcome this problem: 1. Chemical modification of the steroid molecule, 2. parenteral application and 3. esterification in position 17 of the testosterone molecule.

For a more complete description of the many testosterone preparations and routes of administration the reader is referred to a review by Behre and Nieschlag (51). A major goal of the efforts to produce new testosterone preparations for clinical use was to optimize treatment of hypogonadism. Later, when serum levels of testosterone could be determined, an additional goal was to mimic physiological serum testosterone levels as closely as possible (52). As shown in the ensuing text, it took quite long to reach these goals. together with As mentioned above, synthesized testosterone Ruzicka et al. 17-methyl-testosterone and had demonstrated its oral effectiveness. Since the 17-configuration protected against degradation in the liver, it soon was well accepted for clinical use (54). However, due to its 17-structure it was liver toxic, especially under long-term use or at higher doses (55), a feature shared by all 17 substituted androgens. In error some physicians considered liver in 1935