Definition

A nasal gel containing the human androgen testosterone that is used as a replacement agent for low or missing endogenous testosterone caused by various conditions. Upon intranasal administration of testosterone nasal gel using a pump, testosterone is taken up systemically and is irreversibly converted to dihydrotestosterone (DHT) in target tissues by the enzyme 5-alpha reductase. Testosterone or DHT ligand-androgen receptor complexes act as transcription factor complexes, stimulating the expression of various responsive genes. Testosterone and DHT promote the growth, development and maintenance of male sex organs and the maintenance of secondary sex characteristics. In addition, testosterone is irreversibly converted to estradiol by the enzyme complex aromatase, particularly in the liver and adipose tissue.