Nandrolone Phenylpropionate (NPP / Durabolin)

Nandrolone phenylpropionate (NPP), also known as nandrolone phenpropionate, and sold under the brand name Durabolin among others, is an androgen and anabolic steroid (AAS) medication. It has been used primarily in the treatment of breast cancer and osteoporosis in women.

It is administered by injection into muscle once every week.

Although it was widely used in the past, the drug has mostly been discontinued and is now mostly no longer available.

Side Effects

Side effects of NPP include symptoms of masculinization, such as:

• Acne

• Increased hair growth

• Voice changes

• Increased sexual desire

Mechanism of Action

NPP is a synthetic androgen and anabolic steroid, functioning as an agonist of the androgen receptor (AR) — the biological target of testosterone and dihydrotestosterone (DHT).

It has:

• Strong anabolic effects

• Weak androgenic effects

This gives it a mild side effect profile, making it suitable for use in women and children.

NPP is a nandrolone ester and serves as a long-lasting prodrug of nandrolone in the body.

History and Usage

NPP was first described in 1957 and introduced for medical use in 1959. It was the first nandrolone ester to be introduced, followed by nandrolone decanoate in 1962. It has been one of the most widely used nandrolone esters.

In more recent times, it has been largely superseded by nandrolone decanoate, which is longer-acting and more convenient to use.

In addition to its medical use, NPP is also used to improve physique and performance.

The drug is a controlled substance in many countries, and non-medical use is generally illicit.