Norandrostenedione CAS:734-32-7

19-Norandrostenedione (4-estrene-3,17-dione, NOR) is a precursor of the anabolic steroid nandrolone. Until 2005 19-Norandrostenedione was available without prescription in United States, where it was marketed as a prohormone, but it is now classified as a Schedule III drug. It is also banned from use in many sports, including the Olympic Games, under the World Anti-Doping Code.19-Norandrostenedione is readily metabolized to nandrolone after oral administration, but its potency to transactivate the androgen receptor dependent reporter gene expression is 10 times lower as compared to dihydrotestosterone (DHT).

In vivo experiments in castrated rats demonstrated that subcutaneous treatment with 19-norandrostenediones resulted only in a stimulation of the weight of the levator ani muscle, while the prostate and seminal vesicle weights remained completely unaffected. In contrast to its metabolite nandrolones, 19-norandrostenediones highly selectively stimulates the growth of the skeletal muscles but has only weak androgenic properties.

In the early 2000s, contamination of androstenedioe products with traces of 19-norandrostenediones caused false positives for doping tests for nandroloe because 19-norandrosterones is a metabolite of both nandrolones and 19-norandrostenedionse. In a randomized controlled trial trace contamination of androstenedion with 19-norandrostenedie was sufficient for users of androstendioe to test positive for nandrolones.This detail became less relevant after 19-norandrostenedie and androstenediones were banned by major sporting bodies.