Testosterone Undecanoate 250mg/ml — Undecanoate 250 by Dragon Pharma
Undecanoate 250 is Dragon Pharma's formulation of Testosterone Undecanoate at 250mg/ml — the longest-ester injectable testosterone available, with an approximately 20-21 day half-life that enables the least frequent injection schedule of any testosterone formulation. Known pharmaceutically as Nebido (Bayer, 1000mg/4ml) for TRT, the injectable undecanoate ester is the preferred formulation for testosterone replacement therapy in many European countries precisely because its extreme duration allows injections every 10-14 weeks in clinical TRT. For performance use, the long half-life creates specific advantages and significant considerations around PCT timing.
Also searched as: Testosterone Undecanoate, Undecanoate 250, Nebido injectable, long ester testosterone, Dragon Pharma Undecanoate.
The Undecanoate Ester — Why It's Different from All Other Testosterone Esters
The Undecanoate ester is categorically longer than any other testosterone ester in the Dragon Pharma range:
| Testosterone Ester | Half-Life | Injection Frequency | Active T per 250mg |
|---|---|---|---|
| Suspension (no ester) | 2–4 hours | Daily | 250 mg (100%) |
| Propionate | ~2 days | Every other day | ~208 mg (~83%) |
| Enanthate | ~7 days | Twice weekly | ~180 mg (~72%) |
| Cypionate | ~8 days | Twice weekly | ~175 mg (~70%) |
| Decanoate | ~14–15 days | Weekly to biweekly | ~165 mg (~66%) |
| Undecanoate | ~20–21 days | Every 2–4 weeks | ~157 mg (~63%) |
The Undecanoate ester's 11-carbon chain is the longest attached to any injectable testosterone — producing a half-life nearly three times that of Enanthate and nearly ten times that of Propionate. The ester accounts for approximately 37% of the molecule's molecular weight, meaning 250mg of Testosterone Undecanoate contains approximately 157mg of actual testosterone after ester cleavage.
The Nebido Context — Clinical TRT Application
Understanding Undecanoate's clinical use helps frame its performance application:
- Nebido (Bayer HealthCare) is the branded pharmaceutical Testosterone Undecanoate injection — 1000mg in 4ml castor oil — approved and widely prescribed across Europe, Australia and many Asian countries for male hypogonadism TRT
- The clinical TRT protocol: loading injection at week 0, second injection at week 6 (to rapidly establish stable levels), then every 10-14 weeks thereafter — typically only 4-5 injections per year for full testosterone replacement
- This extremely infrequent injection schedule is Nebido's primary clinical advantage over weekly or twice-weekly Enanthate/Cypionate injections — improving patient compliance significantly
- Dragon Pharma's Undecanoate 250 at 250mg/ml in a 10ml vial provides the same pharmaceutical compound in a different format — higher concentration and larger volume, suited to the performance context where higher doses may be used more frequently than clinical TRT
Performance Use — Advantages and Considerations
For performance users, Testosterone Undecanoate's pharmacokinetics create specific trade-offs:
- Advantages: Fewest injections of any testosterone — every 2-4 weeks for performance doses; extremely stable blood levels once steady state is reached (minimal peak-to-trough variation); less injection site management than weekly or twice-weekly protocols
- Disadvantage — slow onset: Testosterone Undecanoate reaches meaningful blood levels slowly — peak concentration from a single injection is reached at approximately 7-10 days, with steady state requiring multiple injections over many weeks. Unlike Propionate or even Enanthate, there is no meaningful "fast kick" — users typically wait 3-4 weeks before experiencing full effects
- Major disadvantage — PCT delay: The ~21-day half-life means the compound is still substantially active 3-4 weeks after the last injection. PCT cannot begin until 4-6 weeks post last injection — substantially longer than Enanthate (2-3 weeks) or Propionate (3-5 days). For longer cycles, this extends the total suppression period considerably
- Dose adjustment inflexibility: If side effects emerge, the effect of a dose change takes 2-3 weeks to manifest in changed blood levels — unlike short esters where daily adjustment has near-immediate effect
Effects and Benefits
- Full testosterone pharmacological profile — all anabolic, androgenic, libido, mood and erythropoietic effects of testosterone
- Fewest injections of any injectable testosterone — every 2-4 weeks for performance doses
- Extremely stable blood levels at steady state — the long half-life produces minimal peak-to-trough variation between injections
- Clinical-grade compound — same active substance as prescription Nebido
- Aromatisation to estradiol — AI management required as with all testosterone formulations
Dosage and Administration
| Application | Dose | Frequency | Notes |
|---|---|---|---|
| TRT-equivalent | 500–750 mg | Every 10–14 weeks | Mirrors clinical Nebido protocol; 2–3ml per injection |
| Performance / cruise | 500–1,000 mg | Every 4 weeks | More frequent than TRT; 2–4ml per injection |
| Loading phase | 500 mg at week 0 + week 6 | Loading then every 4 weeks | Establishes stable levels faster |
At 250mg/ml, a 2ml injection delivers 500mg; a 4ml injection delivers 1,000mg. Castor oil carrier is viscous — use a larger gauge needle for drawing (21g) and a standard 23g for injection. Inject intramuscularly in the gluteal muscle for volumes above 2ml. Estrogen management with Arimidex or Aromasin is required — aromatisation occurs at the same rate as with any testosterone. PCT begins 4-6 weeks after the last injection.
PCT Timing — The Extended Clearance
The most important practical consideration for performance users:
- PCT cannot begin until Testosterone Undecanoate has substantially cleared — with a ~21-day half-life, meaningful blood levels persist for 6-8 weeks after the last injection
- Starting PCT while significant testosterone undecanoate is still circulating causes the exogenous testosterone to suppress the HPG axis that the SERM is trying to stimulate — counterproductive
- Guideline: begin PCT approximately 4-6 weeks after the last injection; confirm testosterone is below therapeutic TRT levels with a blood panel if possible before starting PCT
- Clomid or Nolvadex for a standard 4-week PCT course
Related Products
- Enantat 250 — twice-weekly injection; more flexible dose adjustment; faster PCT timing; the standard performance testosterone base
- Cypionat 250 — similar to Enanthate; twice-weekly; comparable performance profile
- Sustanon 270 — multi-ester blend including Undecanoate; broader pharmacokinetic coverage than single-ester Undecanoate alone
"Testosterone Undecanoate's ~21-day half-life enables once-monthly performance dosing — the least frequent injection schedule of any testosterone in the Dragon Pharma range — at the cost of slow onset, inflexible dose adjustment, and 4-6 weeks post-cycle before PCT can begin."
Storage and Handling
Store Undecanoate 250 at room temperature away from direct sunlight. The castor oil carrier is viscous — warming the vial briefly in warm water before drawing reduces viscosity and eases injection. Use sterile technique for every draw.
