Testosterone can be administered parenterally , but it has more irregular prolonged absorption time and greater activity in muscle in enanthate , undecanoate , or cypionate ester form. These derivatives are hydrolyzed to release free testosterone at the site of injection; absorption rate (and thus injection schedule) varies among different esters, but medical injections are normally done anywhere between semi-weekly to once every 12 weeks. A more frequent schedule may be desirable in order to maintain a more constant level of hormone in the system.  Injectable steroids are typically administered into the muscle, not into the vein, to avoid sudden changes in the amount of the drug in the bloodstream. In addition, because estered testosterone is dissolved in oil, intravenous injection has the potential to cause a dangerous embolism (clot) in the bloodstream.
The side effects of Letrozole can include those surrounding cholesterol, and this is an issue some steroid users tend to have a hard time with. The overwhelming data shows AI’s like Letrozole have very little affect on cholesterol, and if they do have any affect it’s normally insignificant. However, such data and studies rarely take into account the inclusion of anabolic steroids, specifically aromatizing anabolic steroids, and this changes the game. When examining the side effects of Letrozole, it’s important to understand the inclusion of anabolic steroids can change things. Many anabolic steroids have the ability to negatively affect cholesterol; the steroid in question will determine the total potential affect. Oral steroids are normally the harshest as they often significantly increase LDL cholesterol (bad cholesterol) and suppress HDL cholesterol (good cholesterol). Then we have injectable steroids , the their affects on cholesterol can also vary greatly. Trenbolone can have a strong, negative impact on both HDL and LDL. Testosterone can also have an impact on HDL, but normally not very strong. Hormones like Nandrolone will typically fall somewhere in the middle. With the above information in play, although it cannot significantly affect cholesterol on its own, what happens when Letrozole is used with anabolic steroids, specifically aromatizing steroids? Data shows when testosterone is used in therapeutic doses the relative affect on cholesterol is statistically insignificant. When doses are increased to supraphysiological levels, HDL suppression may occur but should not be at a true level of concern. The same data shows things, however, change greatly when the same testosterone is used with an AI like Letrozole. Data shows that a 20-25% reduction in HDL cholesterol is very possible with therapeutic or supraphysiological doses of testosterone. For this reason, a cholesterol friendly diet is important, one that’s rich in omega fatty acids, low in simple sugars and saturated fats and a lifestyle that promotes regular cardiovascular activity.