# Testosterone Cypionate

*Also known as: Test Cyp, TC*

Standard US TRT ester with a slightly longer release tail than enanthate. Steady state ~4–5 weeks.

## Overview

Testosterone cypionate is the most prescribed injectable testosterone ester in the US, used clinically for hormone replacement therapy (TRT) and off-label as a cycle base. Its roughly 8-day half-life (via the cypionate ester) enables once- or twice-weekly injection, with steady state reached after about 5 weeks. The ester controls the release rate: once injected into the muscle, tissue esterases slowly cleave the cypionate chain, releasing free testosterone that binds the androgen receptor and drives protein synthesis, nitrogen retention, and erythropoiesis. It aromatizes to estradiol and 5-alpha-reduces to DHT, so monitoring total/free testosterone at trough, estradiol, hematocrit, lipids, and PSA is central to harm reduction. Twice-weekly injection smooths the peak-to-trough swing and reduces E2 and hematocrit side effects compared to once-weekly dosing. HPTA suppression is complete and rapid, requiring a structured PCT after any non-TRT use. It is not hepatotoxic since it bypasses first-pass metabolism.

## Pharmacokinetics

- **Model tier:** linear-regression
- **Half-life:** 6.9 days (165.60000000000002 hours)
- **Cmax:** 964 ng/dL
- **Tmax:** 4.5 days
- **Bioavailability:** 70%

## Dosing

- **Default dose:** 200 mg
- **Typical range:** 100–600 mg
- **Units:** ng/dL

## Harm reduction

- **Aromatizes:** Yes
- **DHT derivative:** No
- **Injection frequency:** 2×/week
- **Bloodwork range:** 300–1000 ng/dL (Eugonadal total T)

## Detection time (anti-doping)

- **Window:** 60–90 days post-last-dose
- **Target metabolite:** Testosterone/epitestosterone ratio (T/E) + GC/C/IRMS confirmation
- **Assay:** GC-MS/MS (profile) + GC/C/IRMS
- **Notes:** Same steroid-profile/IRMS detection as enanthate; comparable depot half-life.

## Source

- **Label:** Depo-Testosterone PK studies
- **URL:** https://tau.amegroups.org/article/view/11328/13164
- **Notes:** Advanced + Linear Regression model.

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**Canonical URL:** https://anabolicdex.com/compounds/testosterone-cypionate
**Plot:** https://anabolicdex.com/plot?compound=testosterone-cypionate