The oral effectiveness of 17a-alkylated androgens (such as methyltestosterone and methandrostenolone) is due to slower hepatic catabolism so that the alkylated derivatives escape degradation by the liver and reach the systemic circulation. All 17a-alkylated steroids may cause abnormal liver function.
A transdermal therapeutic preparation of testosterone is under investigation, in which a testosterone-loaded patch is applied each day to skin making it possible to sustain serum levels in the normal male range throughout the day. This therapy avoids the wide swings in serum testosterone values that occur between injections of testosterone esters.
