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Testosterone Undecanoate

Name: Testosterone Undecanoate
Brand: Quanta Pharmaceuticals

The longest-acting testosterone ester, studied for stable hormone levels from markedly infrequent dosing.

Testosterone Undecanoate attaches the primary male androgen to an 11-carbon undecanoate ester chain — the longest ester commonly used in testosterone research. This extended chain length slows hydrolysis dramatically, producing a half-life of roughly 21 days, several times longer than enanthate or cypionate. This pharmacokinetic profile has made it a frequent subject of testosterone replacement research, where the goal is stable serum levels with the fewest possible injections rather than rapid, punchy delivery.

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Specifications

Concentration

250mg/ml

Half-Life

21 days

Administration

Injectable

Chemical Structure

C26H40O3

Research Benefits

Extended interval dosing — A ~21-day half-life supports research protocols built around infrequent administration.
Stable serum levels — Slow, steady release avoids the sharp peaks and troughs seen with shorter esters.
TRT-relevant pharmacokinetics — Widely studied in testosterone replacement contexts where consistency matters more than speed.
Reduced injection burden — Fewer administrations are needed to maintain equivalent research exposure.

How It Works

Undecanoate is an 11-carbon fatty acid ester — considerably longer than enanthate (7 carbons) or cypionate (8 carbons) — attached to testosterone's 17-beta hydroxyl group. The longer, more lipophilic chain slows the rate at which esterase enzymes can cleave it once injected, stretching the release of free testosterone out over roughly three weeks.

Once liberated, the testosterone behaves identically to any other ester: binding androgen receptors to drive nitrogen retention, protein synthesis, and the broader anabolic signalling studied throughout the testosterone class. The distinguishing factor is purely pharmacokinetic — how slowly it arrives, not what it does once it does.

⚠ For Research Use Only

This product is supplied strictly for in-vitro laboratory and preclinical research use. It is not a drug, food, dietary supplement, or cosmetic, and is not intended for human or animal consumption, diagnosis, treatment, or prevention of any disease. Testosterone Undecanoate must be handled only by qualified individuals trained in proper laboratory safety procedures.

By purchasing, the buyer confirms this product is being acquired for legitimate research purposes and assumes full responsibility for its handling, storage, and use in compliance with all applicable local, national, and international laws.