As discussed above, if the steroid is 17 alpha alkylated, it will survive this first pass, but not without damaging the liver itself. However, in addition to the portal circulation, there is another pathway that nutrients can take in the small intestine. If a substance is fatty in nature (lipophilic), it will be absorbed as dietary fat, which is incorporated into chylomicra (small fat globules comprised of fat and protein). Rather than being absorbed into portal circulation and shuttled to the liver, the nutrients are absorbed directly into lymphatic circulation, which bypasses the liver entirely. Therefore, researchers have added a lipophilic component to the steroid backbone in an effort to maximize absorption and bypass the first pass through the liver entirely, effectively reducing liver damage while maintaining the integrity of the drug. Once in the lymphatic circulation, the chylomicra will cross over into general blood circulation and affect its target cells. However, even with this increased bioavailability, there is no guarantee that all of the steroid molecules ingested will be activated and passed into lymphatic circulation. The more lipophilic the steroid is made, the increased the absorption rate. A side chain from the steroid must be linked in such a way to allow it to hydrolyze (break down) easily after being absorbed into the bloodstream. This is also a problem. The steroid is able to enter the bloodstream without passing through the liver, but once in the blood stream it must be able to shed its lipophilic side chains so it can be truly activated and express its effect on local tissues. Researchers commonly use two lipophilic side chains to increase the oral bioavailability of the drug through an increase in hepatic absorption. anavar for sale In drugs like Andriol, a long-chain alkyl ester group is used for this purpose. In other drugs (Quinbolone), enyl ether groups are used.
Even with these modifications, lipophilically modified steroids are still not absorbed, nor are they activated, as readily as 17-alpha alkylated steroids. Therefore, steroids that are considered lipophilic, such as Anavar (Oxandrnolone), are not very powerful and will not be an effective drug to use to increase strength and muscle mass. The reason lipophilic steroids are not effective is that there is high variability in the amount of absorption not only between individuals, but between doses with the same individual. When an athlete takes the drug can affect how much of it will be absorbed. Diet also plays a role in this. In diets that are high in fat intake (such as when a bodybuilder is on a bulk cycle), the natural fatty acid intake will limit the amount of steroids that can be taken up as chylomicra in the small intestine. This will further limit the bioavailability of the steroid. The same is true with steroids comprised of an enyl ether.
Categories: None
Post a Comment
Oops!
Oops, you forgot something.
Oops!
The words you entered did not match the given text. Please try again.
Oops!
Oops, you forgot something.