Testosterone Undecanoate
A profile on the ultra-long acting testosterone ester (Nebido), primarily used for medical TRT with injections every 10-14 weeks.
Testosterone Undecanoate
Testosterone Undecanoate is an extremely long-acting ester of testosterone.
It exists in two main forms:
- Oral (Andriol): Unique lymphatic absorption (bypassing liver), but poor bioavailability.
- Injectable (Nebido/Aveed): A massive ester designed for clinical TRT to allow for injections just 4-5 times per year.
This guide focuses on the Injectable form, as it presents unique challenges and benefits for cycle planning.
Quick Specs
| Property | Value |
|---|---|
| Active Compound | Testosterone |
| Half-Life | ~33 Days (Injectable) |
| Detection Time | ~5 Months |
| Anabolic/Androgenic Ratio | 100 : 100 |
| Chemical Family | Testosterone |
| Administration | Injectable (IM - usually Glute) |
Mechanism of Action
The Undecanoate ester renders the testosterone extremely lipophilic (fat-soluble). After injection, it is stored in adipose tissue and released incredibly slowly over months.
Pharmacokinetics & Dosing
Half-Life: ~33 Days
- Clinical Dosing: 1000mg (4ml) injected once every 10-14 weeks.
- Bodybuilding Dosing: Due to the extreme half-life, it is rarely used for cycling. It is impossible to "blast" and then clear the system for PCT. It is strictly a "Cruise" or TRT drug.
- Loading Phase: Because it takes so long to build up, a "loading dose" (a second shot 6 weeks after the first) is often required clinically.
Primary Effects
1. Stability
Once stabilized (which can take 6 months), it offers the most stable blood levels of any testosterone preparation.
2. Convenience
Ideal for "Cruise" phases or frequent travelers who cannot inject weekly.
Side Effects & Harm Reduction
Commitment:
No Turning Back: Once you inject Nebido, you are committed for months. If you have an adverse reaction (e.g., severe acne, anxiety, high estrogen), you cannot just "stop" taking it. The drug will remain in your system for huge amounts of time.
1. Estrogen
Estrogen levels usually remain stable, but if they spike, they stay high for a long time.
2. Injection Volume
Standard ampoules are 4ml (1000mg). Injecting 4ml of oil into a single site can be uncomfortable. It requires a large muscle (Glute/Ventro).
Tracking Test Undecanoate
Using the Anabolic Tracker app:
- Inventory: Add Testosterone Undecanoate.
- Scheduling: Set frequency to Custom (e.g., every 70 days) or create manual entries.
- Plotter: Visualize the incredibly slow release curve. It effectively looks like a flat line after the loading phase.
Disclaimer:
This guide is for informational purposes only. Testosterone is a controlled substance. Misuse can lead to permanent health damage.