Nandrolone phenylpropionate is an injectable form of the anabolic steroid nandrolone. The properties of this drug are strikingly similar to those of Deca-Durabolin, which uses the slower acting drug nandrolone decanoate. The primary difference between these two preparations is the speed in which nandrolone is released into the blood. While nandrolone decanoate provides a release of nandrolone from the area of injection lasting approximately 3 weeks, nandrolone phenylpropionate is active for only about a week. In clinical situations, Deca-Durabolin can thus be injected once every 2 or 3 weeks, while Durabolin is usually administered every several days to once weekly. Otherwise, the two drugs are virtually interchangeable. Like Deca-Durabolin, Durabolin is valued by athletes and bodybuilders for its abilities to promote strength and lean muscle mass gains without significant estrogenic or androgenic side effects.