Nandrolone Phenylpropionate, also known as “NPP” is very similar to the very popular steroid “Deca” which is Nandrolone with a longer ester (Decanoate). Nandrolone Phenylpropionate is, therefore, a shorter acting “Deca” for all practical intents and purposes. Anecdotally, it seems to produce less water retention than its longer acting cousin, and this would be very consistent with injectable testosterones, where we find that shorter esters provide much less water retention.



It’s a progestin, like any Nandrolone derivative, and is made by removing the carbon atom at the 19th position of the Steran Nucleus of testosterone. However, although it’s a progestin, Nandrolone (regardless of ester) doesn’t produce much of what we could properly call estrogenic side effects. Any side effects from Nandrolone Phenylpropionate would therefore more properly be termed progestenic in nature- as it only converts to estrogen at roughly 20% the rate of testosterone.



Regardless of ester, and water retention not withstanding, we find that all of the characteristics of found in one type of Nandrolone are found in any other. Nandrolone, probably owing to its progestenic nature has the ability to improve collagen synthesis  as well as bone mineral content. Clearly this would be a huge benefit to athletes with connective tissue problems or other joint issues, although drug-tested athletes need to avoid Nandrolones because of their detectability in urine for a year to eighteen months after administration. Also, since it is progestin (with slight estrogenic ability), it probably has some very beneficial effects on the immune mediated anti-inflammatory process, thereby soothing joints as well as helping to heal them.