Pharmaceuticals/Chemicals Human clinical data

Estradiol Cypionate

E2 Cyp · Depo-Estradiol

3.7 days

Half-life

2–10 mg

Typical dose

Ongoing (chronic)

Cycle length

Injectable estradiol cypionate used in feminizing HRT.

Key takeaways

Longest-acting common injectable estradiol ester; ~3.7-day half-life, peak ~17 hours.
Approved (Depo-Estradiol) for menopausal symptoms; feminizing use is off-label community practice.
Human PK data is real but old: 1980 ester comparison, monthly-injectable contraceptive trials.
Titrate to serum estradiol at trough; excess levels raise thrombosis risk.

🚧 Expanded guide coming soon. This compound has PK data and a source — a full overview, mechanism, and dosing guide is pending editorial review.

Reported dosing protocols

Protocols reported in research literature and clinic/community use — informational context, not a dosing recommendation.

Use case	Dose	Route	Frequency	Duration
Menopausal symptoms (label)	1–5 mg	IM	Every 3–4 weeks	Ongoing
Feminizing HRT (community/guideline)	2–10 mg	IM or SubQ	Weekly, sometimes split every 5 days	Ongoing

Pharmacokinetic summary

Model tier: Advanced (t½ + Cmax + Tmax + F)
Half-life: 3.7 days
Cmax: 2.8 pg/mL
Tmax: 0.7 days
Bioavailability: 60%
Typical dose: 2–10 mg

Frequently asked questions

Cypionate vs valerate for injections?

Cypionate lasts longer and peaks lower. The 1980 head-to-head found cypionate produced significantly lower estradiol peaks than valerate with a longer tail, which is why cypionate stretches to weekly dosing comfortably while valerate users often notice a day-five dip.

Is there modern clinical evidence behind it?

For menopausal use, it's an approved drug with label dosing. For gender-affirming use, no randomized trials exist; practice rests on older PK studies, physiology, and community bloodwork. Guidelines support injectable estradiol generally without picking an ester.

What estradiol levels are too high?

There's no universal ceiling, but sustained levels far above the physiological follicular range raise thrombosis and breast-tenderness risk without added benefit. Community practice targets trough levels within the cisgender female range and adjusts from symptoms plus bloodwork.

References

ScienceDirect (E2 Cyp PK)
Oriowo et al., Contraception 1980: PK of three estradiol esters — Head-to-head IM PK; cypionate peaked lower and lasted longer than valerate and benzoate.
Sierra-Ramírez et al., Contraception 2011: MPA/estradiol cypionate SC vs IM — Comparative PK of the monthly combination injectable.

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