Injectable Testosterone Cypionate — Individualized Testosterone Support

Route: Intramuscular injection, typically into the gluteus medius, vastus lateralis, or deltoid muscle. Subcutaneous injection at lower volumes has also been used off-label. Use a new sterile needle and syringe for each injection. Warm the oil-based solution to room temperature before drawing. Rotate injection sites to minimize local tissue reactions. Apply pressure to injection site after withdrawal; do not massage.

Dosing is entirely prescriber-determined and individualized based on patient serum testosterone levels, clinical presentation, and treatment goals:

• Standard FDA-approved dosing for male hypogonadism: 50–400 mg IM every 2–4 weeks (less physiologic due to peak-trough variability).
• Endocrine Society-preferred alternative: 75–100 mg IM weekly or 150–200 mg IM every 2 weeks for more stable serum levels.
• Compounded formulations allow individualized concentrations and dosing volumes to match prescribed regimens precisely.
• All doses, concentrations, and schedules are determined by the prescribing clinician with laboratory monitoring.

Testosterone cypionate is an esterified prodrug that, after IM injection into fatty tissue, slowly releases over 1–2+ weeks. Esterases cleave the cypionate ester to yield free testosterone, which exerts effects through two primary mechanisms: (1) Androgen receptor (AR) binding: testosterone (and its active metabolite dihydrotestosterone [DHT], formed by 5α-reductase) binds intracellular AR, forming a receptor-ligand complex that translocates to the nucleus and regulates transcription of androgen-responsive genes — mediating effects on muscle mass, erythropoiesis, libido, bone density, and secondary sexual characteristics; (2) Feedback inhibition: exogenous testosterone suppresses pituitary LH and FSH secretion via negative feedback on the hypothalamic-pituitary axis, reducing endogenous testosterone and spermatogenesis. During testosterone replacement, testosterone is also aromatized to estradiol in peripheral tissues, contributing to bone density maintenance and other physiologic effects.

Testosterone cypionate injection is used prescriber-directed for the management of primary and secondary hypogonadism (hypogonadotropic hypogonadism or testicular failure) in males presenting with symptoms of androgen deficiency: decreased libido, fatigue, erectile dysfunction, depressed mood, decreased muscle mass, or osteoporosis. In female patients, compounded testosterone may be directed by prescribers for specific patient-specific indications (e.g., HSDD) per individualized clinical judgment. Compounded individualized concentrations allow tailoring of dose and volume to clinical need.

Monitoring: Baseline and follow-up serum total testosterone (trough level pre-injection or mid-cycle), hematocrit/hemoglobin (polycythemia risk), PSA (males ≥40 years), liver function, lipid profile, blood pressure, and clinical symptom assessment. Estradiol if gynecomastia or mood changes occur.

Contraindications:

• Known or suspected prostate or breast carcinoma.
• Hypersensitivity to testosterone or sesame/cottonseed oil excipients.
• Females who are pregnant or may become pregnant (virilization of female fetus).
• Serious hepatic disease.

Warnings & Precautions:

• Polycythemia: testosterone stimulates erythropoiesis; hematocrit monitoring required.
• Cardiovascular effects: potential risk of adverse cardiovascular events; use with caution in patients with cardiac, hepatic, or renal disease.
• Venous thromboembolism: risk increase reported with testosterone therapy.
• Peliosis hepatis and hepatic neoplasms: reported with prolonged use (less likely with injectable vs. oral forms).
• Virilization in female partners via skin contact: counsel on handwashing and application precautions.
• Suppression of spermatogenesis: inform male patients desiring fertility.

Drug Interactions:

• Anticoagulants (warfarin): testosterone may potentiate warfarin; monitor INR closely.
• Insulin: may enhance hypoglycemic effect; monitor blood glucose.
• Corticosteroids: concurrent use may cause fluid retention.

Common Side Effects: Injection site pain/induration, acne, oily skin, increased erythropoiesis, mood changes, libido changes, gynecomastia, water retention.

Store at room temperature (15°C–25°C). Protect from light. The oil-based solution should remain clear; if crystallization occurs, gently warm the vial in the hand or warm water bath (do not microwave). Do not freeze. Use aseptic technique for each vial access. Use within the beyond-use date assigned by Genesis Compounding.

How is this injection administered?

Testosterone cypionate is injected intramuscularly into the gluteus, thigh, or deltoid using a sterile needle and syringe. Your prescriber or pharmacist can instruct you on proper self-injection technique, site rotation, and disposal of sharps.

How often do I inject testosterone cypionate?

Frequency is prescriber-determined. Common regimens are once weekly (75–100 mg) or every two weeks (150–200 mg). Weekly injections provide more stable testosterone levels and less peak-trough variation compared to biweekly dosing.

Will testosterone therapy affect fertility?

Yes. Exogenous testosterone suppresses LH and FSH, reducing or stopping sperm production. Men who wish to preserve fertility should discuss alternatives (e.g., clomiphene or hCG) with their prescriber before starting TRT.

What labs do I need while on testosterone therapy?

Your prescriber will monitor serum testosterone levels, hematocrit (red blood cell count), PSA (if applicable), lipid panel, liver function, and blood pressure at regular intervals.

Is this FDA-approved?

No. This is a patient-specific, prescriber-directed 503A compounded preparation from Genesis Compounding. FDA-approved testosterone cypionate injectable products (e.g., Depo-Testosterone®) exist; this compounded version is prepared at individualized concentrations for patient-specific clinical needs.