Testosteronenantat SIT 250 mg/ml

What Is Testosteronenantat SIT and What Is It Used For?

Testosteronenantat SIT is a long-acting injectable androgen containing testosterone enanthate at 250 mg per millilitre. It is licensed for testosterone replacement therapy in adult men with a confirmed diagnosis of primary or secondary hypogonadism, where low endogenous testosterone is demonstrated biochemically and accompanied by clinical symptoms of deficiency. The medicine is given as a deep intramuscular injection, typically every two to three weeks, to restore physiological testosterone levels.

Testosterone is the principal male sex hormone (androgen) and is essential throughout life for the development and maintenance of male reproductive tissues, sexual function, erythropoiesis (red blood cell production), muscle and bone anabolism, and neuropsychological wellbeing. In adult men, serum testosterone normally ranges between 300 and 1 000 ng/dL (approximately 10.4 to 34.7 nmol/L) when measured in the morning. Values below this range, in combination with consistent clinical features, are referred to as testosterone deficiency syndrome or male hypogonadism.

Testosteronenantat SIT belongs to the testosterone ester group of androgens. Esterification with enanthic acid (heptanoic acid) creates a more lipophilic (fat-soluble) compound, which, when dissolved in an oily vehicle and injected into muscle, forms a depot from which the parent hormone is slowly released. After intramuscular administration, enzymes in tissue and plasma hydrolyse the ester bond to liberate free testosterone. The pharmacokinetic profile produces a peak approximately 4–7 days after injection, followed by a gradual decline over 2 to 3 weeks, allowing a dosing interval that is considerably longer than short-acting preparations but shorter than ultra-long-acting esters such as testosterone undecanoate.

According to international guidelines – including the Endocrine Society Clinical Practice Guideline (Bhasin et al., 2018), the European Association of Urology (EAU) Guidelines on Male Hypogonadism, and the American Urological Association (AUA) Guideline – testosterone replacement therapy should be reserved for men in whom low testosterone has been unequivocally demonstrated by at least two morning blood samples and who also report consistent symptoms or signs of deficiency. Testosterone replacement is not indicated for men with normal serum testosterone, for age-related symptoms in otherwise healthy older men, or as a performance-enhancing or anti-ageing therapy.

Recognised clinical features of testosterone deficiency that may, in combination with confirmed biochemical deficiency, support treatment with testosterone enanthate include:

• Sexual symptoms: loss of libido, erectile dysfunction, reduced frequency of morning erections, and decreased sexual thoughts
• Physical symptoms: reduced muscle mass and strength, increased central adiposity, decreased vitality, and decreased bone mineral density with higher fracture risk
• Psychological symptoms: low mood, poor concentration, irritability, reduced motivation, and sleep disturbance
• Haematological findings: unexplained normochromic normocytic anaemia
• Reproductive findings: small or soft testes, infertility, and loss of body or facial hair

Causes of hypogonadism treated with testosterone enanthate

Hypogonadism is broadly classified according to the anatomical level of the defect. Primary (hypergonadotropic) hypogonadism arises from the testes themselves and is typically accompanied by elevated luteinising hormone (LH) and follicle-stimulating hormone (FSH). Secondary (hypogonadotropic) hypogonadism is caused by dysfunction of the hypothalamus or pituitary and is accompanied by inappropriately low or normal LH and FSH. Conditions that may require long-term testosterone replacement with testosterone enanthate include:

• Klinefelter syndrome (47,XXY) and other congenital forms of primary testicular failure
• Post-orchidectomy (surgical removal of the testes) or testicular damage from chemotherapy, radiation, trauma, or orchitis
• Kallmann syndrome and other causes of congenital hypogonadotropic hypogonadism
• Pituitary disorders: adenomas, apoplexy, surgery, radiotherapy, infiltrative disease (haemochromatosis, sarcoidosis)
• Severe systemic illness where functional suppression is expected to be long-lasting

Why testosterone enanthate instead of other preparations?

Testosterone is available in many formulations, each with its own pharmacokinetic profile and practical implications. Testosterone enanthate remains a widely used option because it is inexpensive, reliable, and familiar to prescribers worldwide. Compared with daily transdermal gels, it eliminates the risk of transfer to family members and the need for daily application. Compared with ultra-long-acting testosterone undecanoate injections given every 10–14 weeks, the shorter interval allows faster dose titration and easier discontinuation if adverse effects occur. However, its pharmacokinetic peaks and troughs may produce cyclical changes in mood, energy, and libido between doses, which some patients find inconvenient and which can be mitigated by shortening the dosing interval or by using injections of smaller volumes more frequently.

What Should You Know Before Taking Testosteronenantat SIT?

Testosteronenantat SIT is intended exclusively for adult men with biochemically confirmed hypogonadism. It must not be used in men with known or suspected prostate or breast cancer, in women (especially during pregnancy or breastfeeding), in children, or in anyone with a hypersensitivity to testosterone or arachis (peanut) oil or any excipient. Cardiovascular disease, polycythaemia, sleep apnoea, severe hepatic or renal impairment, and a personal or family history of thrombosis require specialist assessment before starting treatment.

Before the first injection of Testosteronenantat SIT, your doctor should perform a detailed clinical evaluation: history (including cardiovascular risk factors, history of blood clots, sleep apnoea, lower urinary tract symptoms, fertility plans, and family history of prostate or breast cancer), physical examination (including digital rectal examination of the prostate in men over 40, blood pressure, cardiovascular status, and testicular examination), and laboratory tests. Treatment should only start when low testosterone is confirmed by at least two morning total testosterone measurements that are clearly below the locally used laboratory reference range, and after alternative causes of symptoms have been considered.

Absolute contraindications

Testosteronenantat SIT must not be administered in any of the following situations:

• Androgen-dependent carcinoma of the prostate or of the male breast, whether confirmed or suspected
• Past or present hepatic tumours (testosterone esters have been associated with benign and malignant liver tumours, particularly after high-dose or long-term use)
• Hypercalcaemia, which testosterone may worsen, especially in patients with bone metastases
• Pregnancy and breastfeeding – the product may cause virilisation of a female fetus and pass into breast milk
• Use in women for any indication except under the strict supervision of a specialist for very specific conditions (not the scope of this medicine)
• Boys younger than 18 years – testosterone may close the epiphyses prematurely and reduce final adult height
• Known hypersensitivity to testosterone, testosterone enanthate, arachis (peanut) oil, soya, or any listed excipient

Warnings and precautions

Treatment with testosterone enanthate requires careful consideration in the following conditions. None of these is an absolute contraindication, but each requires specialist input and a tailored monitoring plan:

• Cardiovascular disease: a pooled analysis of observational data and the randomised TRAVERSE trial (Lincoff et al., 2023) found testosterone replacement in hypogonadal men with high cardiovascular risk to be non-inferior for major cardiac events, but a small increase in atrial fibrillation, pulmonary embolism and acute kidney injury was observed. Men with unstable angina, recent myocardial infarction, severe heart failure, or uncontrolled hypertension should be stabilised before initiation.
• Polycythaemia / elevated haematocrit: testosterone stimulates erythropoiesis. Baseline haematocrit above 50% should prompt caution; above 54% testosterone is generally contraindicated and treatment must be paused until the value normalises.
• Sleep apnoea: testosterone may worsen obstructive sleep apnoea, particularly in obese men. Known sleep apnoea should be treated (e.g. CPAP) and symptoms re-evaluated during therapy.
• Benign prostatic hyperplasia (BPH) and lower urinary tract symptoms: testosterone may increase prostate volume and worsen urinary symptoms, though it does not cause BPH de novo. Men with moderate to severe symptoms require urological assessment.
• Prostate cancer risk: testosterone does not initiate prostate cancer, but may accelerate pre-existing undiagnosed disease. PSA and digital rectal examination are mandatory at baseline and during treatment.
• Thromboembolism: rare cases of venous and arterial thrombosis have been reported. Risk is increased by smoking, obesity, immobility, previous thrombosis, cancer, and inherited thrombophilias.
• Hepatic impairment: although testosterone esters administered parenterally largely bypass first-pass metabolism, hepatic adenoma and cholestatic changes have been reported. Severe liver disease generally requires an alternative strategy.
• Renal impairment and heart failure: testosterone can cause fluid and electrolyte retention, precipitating oedema, and rarely aggravating heart failure or hypertension.
• Epilepsy and migraine: these conditions may be exacerbated by fluid retention.
• Diabetes mellitus: testosterone may improve insulin sensitivity; glucose-lowering medication may need to be reduced to prevent hypoglycaemia.
• Bone metastases or advanced malignancy: risk of hypercalcaemia requires caution.
• Depression and mental health: mood changes, irritability, insomnia, and, uncommonly, depressive symptoms may occur, particularly in the peri-trough period between injections.

Pregnancy, breastfeeding and exposure of women and children

Testosteronenantat SIT is strictly contraindicated in pregnancy. Testosterone crosses the placenta and can cause masculinisation of a female fetus, including clitoromegaly, labial fusion, and urogenital abnormalities. It is also contraindicated during breastfeeding, because testosterone is lipid soluble and may be excreted in breast milk. Although the injection is given under healthcare supervision and does not pose a transfer risk comparable to gels, pregnant women and women planning pregnancy should not handle unused ampoules or participate in the administration process, and should discuss any exposure with their obstetrician.

Effects on male fertility

Testosterone enanthate suppresses the hypothalamic–pituitary–gonadal axis, leading to reduced LH and FSH secretion and, consequently, to severely impaired spermatogenesis. Most men treated with therapeutic doses of testosterone esters develop oligozoospermia or azoospermia within 3 to 6 months. Recovery after treatment discontinuation is generally expected within 6 to 24 months, but is not guaranteed, especially with prolonged use. Men who wish to preserve fertility should consider sperm cryopreservation before starting therapy or discuss alternative regimens (selective oestrogen-receptor modulators such as clomiphene, aromatase inhibitors, or gonadotropin therapy with hCG ± FSH) with a fertility specialist.

How Does Testosteronenantat SIT Interact with Other Drugs?

Testosterone enanthate interacts with several commonly prescribed medicines. The most clinically important interactions are with oral anticoagulants (warfarin), insulin and oral antidiabetics, corticosteroids and ACTH, and immunosuppressants such as cyclosporine. Dose adjustment or closer monitoring is frequently required. Always provide your prescriber with a complete list of all medicines, supplements, and herbal products before starting therapy.

Interactions occur through a variety of mechanisms: changes in plasma protein binding, modulation of hepatic enzymes, additive pharmacodynamic effects on fluid balance or red cell mass, and, for anticoagulants, changes in clotting factor synthesis. Although the parenteral route of Testosteronenantat SIT avoids first-pass metabolism, interactions that occur downstream (at the receptor level, on coagulation, or on electrolyte balance) still apply. The following sections summarise the most relevant interactions.

Major interactions

Minor interactions and supplements

Other potential interactions worth discussing with the prescriber or pharmacist include:

• Oxyphenbutazone: may increase plasma testosterone concentrations when given concomitantly
• Other anabolic steroids or selective androgen receptor modulators (SARMs): combined use increases the risk of virilising and cardiometabolic side effects; should never be combined with testosterone enanthate
• Gonadotropin-releasing hormone (GnRH) analogues (leuprorelin, goserelin): testosterone antagonises the therapeutic effect of these agents used for prostate cancer – combination is contraindicated
• 5-alpha-reductase inhibitors (finasteride, dutasteride): reduce conversion of testosterone to dihydrotestosterone; may attenuate effects on scalp hair or prostate but do not eliminate androgenic effects
• Herbal products (DHEA, tribulus, saw palmetto, fenugreek, ashwagandha): limited clinical data; unregulated products may contain undeclared androgens and interfere with testosterone assays – generally avoid
• Laboratory tests: testosterone can alter thyroid function tests (low total T4), decrease sex hormone binding globulin (SHBG), increase haematocrit and haemoglobin, and modestly alter lipid and liver enzyme panels – inform laboratory of therapy

Always provide a complete and up-to-date medication list to your prescriber and pharmacist, including over-the-counter medicines, vitamins, and any performance, weight-loss, or “male enhancement” supplements.

What Is the Correct Dosage of Testosteronenantat SIT?

Testosteronenantat SIT 250 mg/ml is administered as a deep intramuscular injection, typically 250 mg (1 ml) every 2 to 3 weeks. The interval is individualised based on serum testosterone trough levels, clinical response, haematocrit, and patient preference. Most men settle on 250 mg every 14 to 21 days; intervals shorter than 10 days or longer than 28 days are outside standard practice. The injection must be given slowly by a trained healthcare professional into the upper outer quadrant of the gluteus medius.

There is no single “correct” dose of testosterone enanthate; treatment is titrated to the individual. The therapeutic goal is to maintain trough serum testosterone within the middle third of the healthy adult male reference range while relieving symptoms, avoiding supraphysiological peaks, and keeping haematocrit below 54%. The first dose is usually given after baseline investigations, and the second trough blood test is drawn immediately before the third or fourth injection, once pharmacokinetic steady state is approached.

Adults – standard starting dose

Dose adjustment based on monitoring

How the injection is administered

Testosteronenantat SIT is an oily depot injection and must be given by a healthcare professional into the muscle. Self-injection is not standard practice with this preparation in most countries. The following steps reflect current clinical practice:

1. Verify patient identity, drug, strength, dose, expiry date, and that the ampoule contents are clear, yellow, oily, and free from particles or cloudiness.
2. Warm the ampoule briefly in the hand to aid aspiration – oily solutions are more viscous at low temperature.
3. Draw up the dose with a large-bore needle (21G is common), then replace the needle with a 21G or 22G needle for injection to reduce contamination of the outer needle surface.
4. Select the upper outer quadrant of the gluteus medius (ventrogluteal technique is an alternative). Use aseptic technique.
5. Aspirate before injecting to exclude inadvertent intravascular placement (an oil embolism is a rare but serious risk).
6. Inject slowly (over approximately 60 seconds for 1 ml) to reduce pain and risk of oil micro-embolism.
7. Observe the patient for at least 5 minutes after injection for cough, chest tightness, dyspnoea, or syncope, which may signal pulmonary oil micro-embolism or anaphylactic reaction.
8. Document date, site, batch number, and any immediate reactions in the patient record.

Children and adolescents

Testosteronenantat SIT is not recommended in children. In boys younger than 18, exogenous testosterone can induce virilisation, priapism, and premature closure of the bone growth plates, leading to a reduced final adult height. Delayed puberty in specific paediatric conditions may occasionally be treated with lower short-acting testosterone regimens under strict paediatric endocrinology supervision using different preparations, but this falls outside the licensed use of Testosteronenantat SIT.

Elderly men

Age itself is not a contraindication, but older men are more likely to have prostate abnormalities, cardiovascular disease, and polycythaemia. The Endocrine Society recommends against routine testosterone replacement solely for age-related testosterone decline in otherwise healthy older men. When treatment is clinically justified for confirmed hypogonadism, elderly men should undergo more intensive monitoring: PSA and haematocrit every 3–6 months during the first year and at least every 6 months thereafter, together with regular cardiovascular risk assessment.

Hepatic or renal impairment

No specific licensed dose adjustment exists for Testosteronenantat SIT in hepatic or renal impairment, but caution is advised. Severe hepatic disease is a relative contraindication because of the historical association of testosterone esters with cholestatic changes and hepatic tumours. In renal impairment, sodium and water retention may exacerbate oedema and hypertension; cardiovascular and fluid status should be monitored.

Missed dose

If an injection appointment is missed, it should be rescheduled as soon as practicable. Do not “catch up” by taking a double dose. A short delay (a few days) is clinically insignificant, but longer intervals may allow testosterone levels to fall below the target range and reintroduce symptoms. Inform your doctor if you anticipate prolonged delays so the interval strategy can be reviewed.

Overdose

Acute overdose with testosterone enanthate is rare because of the supervised route of administration, but accidental administration of a much larger dose, or rapid intravenous injection, may produce acute androgenic or pulmonary symptoms. Signs of chronic overdose (or supraphysiological dosing, often associated with misuse) include polycythaemia, severe acne, aggressive behaviour, priapism, gynaecomastia, fluid retention, hypertension, and abnormal liver enzymes. Management is symptomatic and supportive: discontinuation or dose reduction, phlebotomy for severe polycythaemia, symptomatic treatment of priapism, and cardiovascular monitoring. Accidental oral ingestion by a child should prompt immediate contact with a poison control centre.

What Are the Side Effects of Testosteronenantat SIT?

The most frequent side effects of testosterone enanthate injections are injection-site reactions, acne, oily skin, mood changes (irritability, aggressiveness), increased libido, gynaecomastia, and increased haematocrit or haemoglobin. Clinically important but less common adverse effects include polycythaemia, worsening of sleep apnoea, fluid retention, hypertension, lipid abnormalities, and thromboembolism. Rare but serious adverse effects include priapism, pulmonary oil micro-embolism at the time of injection, and hepatic neoplasm with long-term high-dose exposure.

Like all hormone therapies, testosterone enanthate is associated with a range of adverse effects, most of which are predictable from the pharmacology of androgens, dose-dependent, and reversible with dose reduction or discontinuation. Adverse effects tend to cluster either at the peak (days 2–7 after injection: acne, aggressiveness, peripheral oedema) or at the trough (end of dosing interval: fatigue, low mood, decreased libido). Smoothing this pattern by shortening intervals or using smaller volumes more frequently can materially improve tolerability.

Lipid changes (reduced high-density lipoprotein cholesterol) are typically modest at replacement doses. Men with pre-existing dyslipidaemia may require optimisation of lipid-modifying therapy during TRT. Minor androgenic effects such as scalp hair thinning, increased body hair, and acne are largely cosmetic but may be distressing and should be discussed openly with the prescribing clinician, who can consider dose adjustment or adjunctive therapy (for example, finasteride for BPH symptoms or topical agents for acne).

How Should Testosteronenantat SIT Be Stored?

Testosteronenantat SIT ampoules should be stored in the original packaging below 30°C (or according to the specific storage statement on the label in your country), protected from light, and kept out of reach of children. Do not refrigerate or freeze. Do not use after the expiry date printed on the carton and ampoule. Unused or expired ampoules must be returned to a pharmacy for safe disposal; never discard into household waste or wastewater.

Correct storage preserves the chemical integrity of the oily solution and prevents accidental exposure. Testosteronenantat SIT is usually supplied in 1 ml glass ampoules containing 250 mg of testosterone enanthate in a sterile oily vehicle. Key storage principles are:

• Temperature: store below 30°C (some packs specify below 25°C); do not refrigerate or freeze because low temperature increases viscosity and may cause precipitation of the active substance, which resolves on rewarming but can make aspiration and injection difficult.
• Protection from light: keep ampoules in the outer carton until use. Testosterone esters can undergo minor photo-oxidative degradation if exposed to prolonged direct sunlight.
• Physical inspection: before use, a healthcare professional should inspect the ampoule. The solution should be clear and yellow-brown. Discard if cloudy, discoloured, or containing visible particles.
• Child safety: store in a place inaccessible to children. Accidental exposure in children can cause virilisation and premature puberty.
• Expiry: the expiry date refers to the last day of the month printed. Do not use after this date.
• Disposal: return unused ampoules and empty ampoules to a pharmacy or follow local regulations for pharmaceutical waste. This protects the environment and reduces the risk of accidental or illicit use.
• Sharps disposal: used needles and syringes must be placed in an approved sharps container and disposed of according to local regulations.

What Does Testosteronenantat SIT Contain?

Each 1 ml of Testosteronenantat SIT solution for injection contains 250 mg of testosterone enanthate as the active ingredient, dissolved in a sterile oily vehicle. Excipients typically include a vegetable oil (such as castor oil or refined oil) and benzyl benzoate as a solubiliser. The exact excipient list is provided in the country-specific product information; always check the package leaflet, particularly if you have a known hypersensitivity or allergy to oils.

Active ingredient

The active substance is testosterone enanthate (also spelled testosterone enantate), the enanthic acid ester of testosterone. Once injected, the ester is hydrolysed slowly by tissue esterases to release free testosterone, which binds to the androgen receptor in target tissues and mediates all physiological androgenic and anabolic effects. Each 1 ml ampoule contains 250 mg of testosterone enanthate, corresponding to approximately 180 mg of testosterone base.

Excipients (inactive ingredients)

Typical excipients used in Testosteronenantat SIT 250 mg/ml solution for injection include:

• Oily vehicle (e.g. castor oil, refined castor oil, or similar): provides the lipophilic environment required to dissolve the ester and creates the slow-release depot after injection.
• Benzyl benzoate: a solubiliser and co-solvent used to reduce the viscosity of the oily vehicle and aid dissolution of the ester. May rarely cause hypersensitivity.
• (Historically) arachis (peanut) oil: used in some older testosterone ester preparations. Check the current country-specific leaflet to confirm the vehicle used in your product.

Presentation and packaging

Testosteronenantat SIT is supplied as a clear, yellowish, oily solution in single-use glass ampoules. Standard pack sizes typically include 1, 3, or 5 ampoules of 1 ml (250 mg). Not all pack sizes are marketed in every country. The product is supplied only through pharmacies on a valid medical prescription from a qualified prescriber.

What Monitoring Is Required During Testosterone Enanthate Therapy?

Systematic monitoring is a cornerstone of safe testosterone replacement therapy. Recommended assessments include serum testosterone at trough, full blood count with haematocrit, PSA, lipids, liver function, blood pressure, prostate examination (in men over 40), symptom review, and mood assessment. These are performed at baseline, at 3, 6, and 12 months during the first year, and at least annually thereafter, or more often if clinically indicated.

The Endocrine Society, the European Association of Urology, and the American Urological Association all recommend structured, protocol-driven follow-up for men on testosterone replacement therapy. The aim is threefold: (1) to confirm that the prescribed dose and interval achieve physiological serum testosterone, (2) to detect predictable adverse effects (polycythaemia, prostate changes, lipid changes, hepatic effects) early, and (3) to continuously re-evaluate the balance of benefit and harm.

Recommended monitoring schedule

Timing of the trough testosterone blood sample

The pharmacokinetic profile of testosterone enanthate produces a peak approximately 4–7 days after injection and a trough immediately before the next injection. To guide dose adjustment, serum testosterone should be measured immediately before the next dose, typically after three to four injections at a stable schedule, when steady state is approximated. Peak levels (sampled 2–5 days after injection) are sometimes useful if supraphysiological concentrations are suspected. Symptoms occurring only in the final days of the interval suggest that a trough is too low and that the interval should be shortened.