Boldenone Undecylenate (Equipoise)

Overview

Boldenone undecylenate (Equipoise, EQ) is a long-acting injectable androgen originally developed for veterinary use (as Parenabol briefly in humans, then as Equipoise for horses). It is a testosterone analog with a double bond at the 1,4 position, which reduces both androgenic and estrogenic activity relative to testosterone, though it still aromatizes weakly. It binds the androgen receptor and drives steady erythropoiesis (the basis for the reputation for endurance and slow, lean gains). Its 14-day half-life produces a slow rise and a very long tail, so research protocols have used 1-2 injections per week with a multi-week run-up to steady state. Hepatotoxicity is rated none and the side-effect profile is comparatively mild. HPTA suppression is real but slower than with shorter esters.

Pharmacokinetic summary

Model tier

Advanced (t½ + Cmax + Tmax + F)

Half-life

14 days

Cmax

600 ng/dL

Tmax

6.0 days

Bioavailability

63%

Typical dose

200–600 mg

Harm reduction

Aromatizes

Yes

DHT derivative

No

Injection frequency

2×/week