In addition to 6β- and 16β-hydroxytestosterone, 1β-, 2α/β-, 11β-, and 15β-hydroxytestosterone are also formed as minor metabolites. The 6β-hydroxylation of testosterone is catalyzed mainly by CYP3A4 and to a lesser extent CYP3A5 and is responsible for 75 to 80% of cytochrome P450-mediated testosterone metabolism. A small portion of approximately 3% of testosterone is reversibly converted in the liver into androstenedione by 17β-HSD. The conjugates of testosterone and its hepatic metabolites are released from the liver into circulation and excreted in the urine and bile. Androsterone and etiocholanolone are then glucuronidated and to a lesser extent sulfated similarly to testosterone. Approximately 50% of testosterone is metabolized via conjugation into testosterone glucuronide and to a lesser extent testosterone sulfate by glucuronosyltransferases and sulfotransferases, respectively. It is bound 65% to sex hormone-binding globulin (SHBG) and 33% bound weakly to albumin. Intramuscular injection of testosterone propionate as an oil solution, aqueous suspension, and emulsion has been compared. Buccal tablets of testosterone propionate were previously available as well. It is specifically approved for the treatment of hypogonadism in men, breast cancer, low sexual desire, delayed puberty in boys, and menopausal symptoms. It was the first testosterone ester to be marketed, and was the major form of testosterone used in medicine until about 1960. Many men will self-prescribe and self-administer TRT after getting a diagnosis of a low testosterone condition. This could be as low as 20mg per week, which can still bring about symptoms of virilization in women. There is hardly a better introduction to using AAS than this, and side effects will be minimal or non-existent. Still, such use of this steroid is rarely considered necessary or beneficial. There is no FDA-approved androgen preparation for the treatment of androgen insufficiency; however, it has been used as an off-label use to treat low libido and sexual dysfunction in older women. Testosterone may prove to be an effective treatment in female sexual arousal disorders, and is available as a dermal patch. In non-human primates, it may be that testosterone in puberty stimulates sexual arousal, which allows the primate to increasingly seek out sexual experiences with females and thus creates a sexual preference for females. The reflexive testosterone increases in male mice is related to the male's initial level of sexual arousal. Common side effects from testosterone medication include acne, swelling, and breast enlargement in males. The brain is also affected by this sexual differentiation; the enzyme aromatase converts testosterone into estradiol that is responsible for masculinization of the brain in male mice. Adult testosterone effects are more clearly demonstrable in males than in females, but are likely important to both sexes. Being pure testosterone, it comes with a very short half-life of as little as two hours and, therefore, requires regular injections to maintain blood levels. Both are excellent for muscle gains, but NPP will give you more significant gains and be quicker than testosterone propionate. Particularly in regards to stress on the cardiovascular system, androgenic and estrogenic effects, and in some cases, you will start to deal with oral steroids, which are liver toxic. A maximum beginner cycle of 500mg weekly for a 10-week cycle provides a good introduction for the new steroid user with a balance between results and side effects. Beginners who are getting their first experience with steroids will find that Testosterone Propionate brings about substantial muscle gains. Stacking it with more cardiovascular-stressing steroids will undoubtedly raise the risk. When used at moderate doses and for limited cycle lengths, Testosterone Propionate should not cause the majority of users serious cardiovascular issues. More so if you have any existing high cholesterol issues or general cardiovascular-related health problems. Testosterone Propionate may cause negative changes to your cholesterol levels. Testosterone Propionate is a testosterone ester that some people love, while plenty of others will never see the need to use it. This means that at its core, Testosterone Propionate is simply pure testosterone and, therefore, comes with an anabolic and androgenic rating of 100 and 100. When injected, the ester slowly detaches in a controlled release time, and the testosterone becomes active. If you’re a novice steroid user, it can be tempting to choose Testosterone Propionate as your preferred first testosterone steroid – but there are some downsides to consider first seriously. have been undertaken on the relationship between more general aggressive behavior, and feelings, and testosterone. Nearly all studies of juvenile delinquency and testosterone are not significant.}