I believe methylation protects a lot the steroid for being destroyed by the liver but not 100%, in anabolics 2007 Llewellyn refers that they should be taken empty stomach to increase absorption and see this from PA also:
17alpha alkylated steroids
Scientists have developed several synthetic testosterone derivatives that have increased oral bioavailability. The first synthetic alteration that scientists utilized is known as 17 alpha alkylation. 17a alkylation involves the addition of an alkyl group (methyl or ethyl) to the alpha position of the 17 carbon of the steroid backbone. The alkylation at this position prevents the major route of androgen deactivaton – oxidation to a 17-keto steroid - from taking place.
This allows a large part of the steroid to avoid liver first pass metabolic degradation. Examples of 17a alkylated steroids are methyltestosterone and Norethandrolone (Nilevar)
While 17a alkylation is a very effective means of rendering steroids orally active, it suffers from a serious drawback. These steroids are all to some extent toxic to the liver. Some are more toxic than others, but they all have been associated with this problem. Jaundice is not completely uncommon with the usage of this stuff, although this condition is generally confined to individuals who are predisposed to liver problems. Several cases of liver cancer have supposedly been linked to 17a alkylated steroids, however, nothing definitive has been established in this regard. On the other hand, it is somewhat common to observe increases in blood test indicators of liver stress such as BSP retention, and intrahepatic cholestasis (a condition where bile clogs up and stops flowing from the liver).
While the dangers of 17a alkylated steroids are not trivial, they still comprise some of the most potent anabolic agents available, and therefore their use continues. Most smart bodybuilders are aware of the potential toxicities of these steroids, and therefore they are judicious with their use of them
notice the bold, large part not 100%, it may depend on the individual, i suppose:think: