The side effects of Nebido can include those of an androgenic nature. The androgenic side effects of Nebido are, however, highly dependent on genetic predispositions and will not affect all men. The possible androgenic side effects of Nebido include accelerated hair loss in those predisposed to male pattern baldness, acne in sensitive individuals and body hair growth.
While by no means always necessary, some men may find the use of a 5-alpha reductase inhibitor to be useful. The testosterone hormone is metabolized by the 5-alpha reductase enzyme, which reduces the testosterone hormone to dihydrotestosterone (DHT). The DHT is what leads to the androgenic related effects. By incorporating a 5-alpha reductase inhibitor, you will reduce the hormones androgenicity. It will not be a complete reduction, but it will be significant. However, such inhibitors are not always recommended and should only be used as needed as they can hinder the potency of the testosterone hormone.
The discovery of the first competitive progesterone antagonist RU 38 486 has initiated an intense search for more potent and more selective anti-progestins. Among several hundreds of compounds under preliminary investigation, biological characterization is most advanced for derivatives RU 38 486, ZK 98 734 and ZK 98 299. These compounds do not only differ in relative potency, but are clearly distinguished by their different behaviour in various animal models. Emphasis is laid on the synthetic problems associated with chemical operations in a sterically crowded environment as represented by structures RU 38 486 and ZK 98 299.
Biosynthesis of steroid hormones requires a battery of oxidative enzymes located in both mitochondria and endoplasmic reticulum. The rate-limiting step in this process is the transport of free cholesterol from the cytoplasm into mitochondria. Within mitochondria, cholesterol is converted to pregnenolone by an enzyme in the inner membrane called CYP11A1. Pregnenolone itself is not a hormone, but is the immediate precursor for the synthesis of all of the steroid hormones. The following table delineates the enzymes required to synthesize the major classes of steroid hormones.