 The C1α methyl group of mesterolone inhibits its hepatic metabolism and thereby confers significant oral activity, although its oral bioavailability is still much lower than that of 17α-alkylated AAS.In any case, mesterolone is one of the few non-17α-alkylated AAS that is active with oral ingestion.Uniquely among AAS, mesterolone has very high affinity for human serum sex hormone-binding globulin (SHBG), about 440% that of DHT in one study and 82% of that of DHT in another study.