COMPOUND

Compounds / TRT and hormones

Test Enanthate

Testosterone Enanthate Injection USP (Delatestryl, Xyosted SC autoinjector, generic)

TRT and hormones IM · SubQ FDA approved

Long-acting injectable testosterone ester suspended in sesame oil. Most widely used TRT ester globally outside North America (where Cypionate dominates). Releases free testosterone slowly over 7-10 days via systemic ester hydrolysis.

At a glance

Half-life
~7 days Effective t½ ~7 days IM (Delatestryl label); SubQ depot release extends effective t½ further with lower Cmax and reduced peak-trough swing (Xyosted autoinjector PK).
Routes
IM · SubQ
Vial sizes
1000 mg · 2000 mg
Evidence base
4 studies 4 human

Mechanism

7-carbon ester attached to the 17-beta hydroxyl of testosterone. After deep IM or SubQ injection into an oil depot, the prodrug diffuses slowly into circulation; serum/tissue esterases cleave the ester bond to release free T. Depot release rate (not ester hydrolysis) is rate-limiting: Tmax ~24-72h, effective t½ ~7d IM. SubQ depots release more slowly with longer effective t½ and lower peak-to-trough ratio. Free T then binds androgen receptors and is peripherally converted to DHT (5-AR) and estradiol (aromatase).

Dosing

Any amounts shown here are reported from published studies only. 4 of 4 catalogued studies involved human subjects. COMPOUND does not publish its own dosing guidance.

Published evidence

  1. Human RCT 2023

    Cardiovascular Safety of Testosterone-Replacement Therapy

    Lincoff AM, Bhasin S, Flevaris P, et al. N Engl J Med

    TRAVERSE: TRT non-inferior to placebo for MACE in 5246 hypogonadal men with elevated CV risk over 27.1 mo. Increased rates of atrial fibrillation, AKI, and pulmonary embolism observed.

    PMID 37326322

  2. Human RCT 2015

    Pharmacokinetic Profile of Subcutaneous Testosterone Enanthate Delivered via a Novel Prefilled Single-Use Autoinjector

    Kaminetsky J, Jaffe JS, Swerdloff RS Sex Med

    Phase II study establishing SubQ Test E PK with novel autoinjector: basis for Xyosted approval.

    PMID 26797061

  3. Human observational 2020

    Occurrence of Pulmonary Oil Microembolism After Testosterone Undecanoate Injection

    Pastuszak AW, Hu Y, Freid JD Sex Med

    Comparator data showing POME is essentially specific to undecanoate, not enanthate or cypionate at standard doses.

    PMID 32184081

  4. Human observational 2014

    Patient satisfaction with testosterone replacement therapies

    Kovac JR, Rajanahally S, Smith RP, et al. J Sex Med

    IM esters preferred over gels for symptom resolution and patient satisfaction.

    PMID 25234269

Reported side effects

Polycythemia / hematocrit elevation
Very common Moderate · Higher with weekly IM peaks vs daily/EOD SubQ. HCT >54% is donation/dose-reduction trigger.
Estradiol elevation / gynecomastia
Common Mild · Aromatization is dose-related; managed with dose split or low-dose anastrozole if symptomatic.
Acne / oily skin / scalp hair loss
Common Mild · DHT-mediated; worse in genetically predisposed.
Testicular atrophy and HPTA suppression / fertility loss
Very common Moderate · Universal with monotherapy. Adjunct HCG or enclomiphene is described in the literature as preserving intratesticular T and spermatogenesis.
Injection site reaction (PIP / nodule)
Common Mild · Sesame oil vehicle. Warming oil and slow injection helps.
Sleep apnea worsening
Occasional Moderate · Screen with overnight oximetry if symptoms or risk factors.
Edema / fluid retention
Occasional Mild · More common at supraphysiologic doses.
Atrial fibrillation
Rare Serious · Statistically significant increase observed in TRAVERSE 2023 (PMID 37326322).
Pulmonary embolism / VTE
Rare Serious · Modest but real increase in TRAVERSE; check for personal/family thrombophilia.

Interactions

  • Anastrozole Synergy

    Anastrozole inhibits aromatase, blunting peripheral T-to-E2 conversion. Common adjunct when E2 climbs symptomatically (>40 pg/mL with gyno, water retention, mood). Most TRT users do NOT need it.

  • HCG Synergy

    HCG mimics LH at testicular Leydig cells, preserving intratesticular T and spermatogenesis during exogenous T suppression of HPTA.

  • Enclomiphene Redundant

    Enclomiphene as monotherapy raises endogenous T via SERM action, duplicative with exogenous Test E.

Reconstitution and storage

Not applicable: supplied as oil solution ready to inject. Warm vial in hand for 1-2 min to reduce viscosity. Standard concentration 200 mg/mL.

Room temperature 20-25°C, protect from light. Do not refrigerate (oil thickens).

Open the reconstitution calculator for Test Enanthate