Nandrolone

Deca and NPP are injectable nandrolone esters. People seek them for mass, strength, and joint comfort, but those three claims do not have the same evidence.

tier A · androgens · +2.6 kg fat-free mass in an 8-week bodybuilder RCT

verdict

The muscle effect is real. A bodybuilder trial increased fat-free mass 2.6 kg, and a 20-trial meta-analysis found a smaller pooled lean-tissue gain. Strength was inconsistent, fat loss was not demonstrated, and joint repair remains an anecdotal claim.

the core tension

Lean-mass gain is supported. A universal half-life, fat loss, reliable strength gain, joint repair, and safety for stacks are not.

what it is

Nandrolone is a 19-nor anabolic-androgenic steroid. Deca-Durabolin used the decanoate ester and Durabolin used phenylpropionate. Both are intramuscular oil depots that release free nandrolone, but they do not share one release curve.

what it does

Free nandrolone activates the androgen receptor. Across 20 randomized trials, nandrolone decanoate increased lean soft tissue by 1.59 kg on average, but did not significantly improve handgrip or knee-extension strength and did not reduce fat mass.

origin

US approval for Durabolin phenylpropionate ended in 2018 and Deca-Durabolin decanoate ended in 2024. Australia's TGA currently lists a nandrolone decanoate injection.

does it work

In 16 experienced male bodybuilders, eight weeks of nandrolone decanoate increased body mass 2.2 kg and fat-free mass 2.6 kg. Total body water increased 1.4 kg, while fat mass and hydration of fat-free mass did not change. That supports added muscle, not a dry look or fat loss.

key facts

• molecular formula: C28H44O3 (decanoate); C27H34O3 (phenylpropionate)
• molecular weight: 428.6 g/mol (decanoate); 406.6 g/mol (phenylpropionate)
• amino acids: n/a (steroidal small molecule, not a peptide)
• half-life: decanoate apparent terminal half-life 7 to 12 days in humans; phenylpropionate has a different, shorter absorption profile
• type: 19-nor anabolic-androgenic steroid administered historically as intramuscular decanoate or phenylpropionate ester
• CAS: 360-70-3 (decanoate); 62-90-8 (phenylpropionate)
• +2.6 kg fat-free mass in bodybuilder RCT
• +1.59 kg pooled lean soft tissue across 20 RCTs
• 7 to 12 d human decanoate terminal range
• 2024 Deca-Durabolin US withdrawal effective

frequently asked questions

Does Deca repair joints?

The named forum record describes temporary pain relief, not healed cartilage, tendon, or ligament. That distinction matters because reduced pain can mask an injury. The controlled human evidence on this page supports lean-tissue effects, not joint repair.

related peptides

• testosterone: the other clinically characterized injectable androgen
• Trenbolone: another 19-nor androgen with no modern human therapeutic PK
• Boldenone: a veterinary long-ester comparator with animal-only PK

reptides grades the research record and cites the literature behind every call. research reference only; not medical advice.