Nandrolone Phenylpropionate (NPP) is the lesser known and less popular phenylpropionate ester version of nandrolone. First off its important to understand the difference between what we know as 'deca' and what we know as "NPP". To put it in simple terms the difference is simply the ester. NPP has the shorter ester while deca durabolin version of nandrolone has the longer 'deca' ester. Many lifters have no clue they can use the compound they love so much in a shorter ester. The only disadvantage would be the amount of injections, the shorter ester would have to be injected every other day or every 3 days at the most, while the long 'deca' ester can be injected once or twice a week. However the advantages are there which I will discuss as we go along.
Trenbolone is also much more potent than testosterone at suppressing endogenous androgen production. This makes clear the fact that estrogen is not the only culprit with negative feedback inhibition, as here there is no buildup of this hormone to report here. There is however some activity as a progestin inherent in this compound, as trenbolone is a 19-nortestosterone (nandrolone) derivative (a trait characteristic of these compounds). However it seems likely that much of its suppressive nature still stems from its powerful androgen action. With the strong impact trenbolone has on endogenous testosterone, of course the use of a stimulating drug such as HCG and/or Clomid®/Nolvadex® is recommended when concluding steroid therapy (a combination is preferred). Without their use it may take a prolonged period of time for the hormonal balance to resume, as the testes may at first not be able to normally respond to the resumed output of endogenous gonadotropins due to an atrophied state. Those who have used Parabolan regularly would often claim it to be indispensable. A weekly dosage of 3 ampules (228mg) was the most popular range when running a cycle, however many did find it highly effective in lesser amounts. Although a weekly administration schedule would prove sufficient, athletes usually injected a single ampule per application, the total amount spread evenly throughout the week. While Parabolan is quite potent when used alone, it was generally combined with other steroids for an even greater effect. Leading up to a show one could successfully add a non-aromatizing anabolic such as Winstrol® or Primobolan®. Such combinations will elicit a greater level density and hardness to the build, often proving dramatic to a stage appearance. We could also look for bulk with this drug, and addition stronger compounds like Dianabol or Testosterone. While the mass gain would be quite formidable with such a stack, some level of water retention would probably also accompany it. Moderately effective anabolics such Deca-Durabolin® or Equipoise® would be somewhat of a halfway point, providing extra strength and mass but without the same level of water bloat we see with more readily aromatized steroids.
Heavy consumption of the essential amino acid lysine (as indicated in the treatment of cold sores) has allegedly shown false positives in some and was cited by American shotputter C. J. Hunter as the reason for his positive test, though in 2004 he admitted to a federal grand jury that he had injected nandrolone.  A possible cause of incorrect urine test results is the presence of metabolites from other AAS, though modern urinalysis can usually determine the exact AAS used by analyzing the ratio of the two remaining nandrolone metabolites. As a result of the numerous overturned verdicts, the testing procedure was reviewed by UK Sport . On October 5, 2007, three-time Olympic gold medalist for track and field Marion Jones admitted to use of the drug, and was sentenced to six months in jail for lying to a federal grand jury in 2000.