Nebido (Testosterone Undecanoate)

Nebido is an androgen replacement therapy used to correct testosterone deficiency in men.

• Primary hypogonadism: restores physiological testosterone levels to improve libido, energy, muscle mass and bone density.
• Secondary hypogonadism: compensates for pituitary or hypothalamic failure, normalising hormonal balance.
• Testosterone deficiency in adult males: alleviates symptoms such as fatigue, reduced sexual desire and mood disturbances.

• After intramuscular injection, testosterone undecanoate is slowly hydrolysed to testosterone. The liberated testosterone binds intracellular androgen receptors, modulating gene transcription that drives anabolic processes (protein synthesis, erythropoiesis) and androgenic effects such as development of male secondary sexual characteristics.

Nebido may be associated with a range of adverse reactions.

Common Side Effects

• Injection site pain: mild to moderate discomfort at the injection site.
• Acne: increased sebaceous gland activity leading to skin eruptions.
• Fluid retention: mild peripheral oedema in some patients.

Serious or Rare Side Effects

• Cardiovascular events: possible increased risk of myocardial infarction or stroke.
• Polycythemia: elevated red blood cell mass requiring monitoring.
• Severe allergic reaction: anaphylaxis or angioedema requiring immediate medical attention.

Nebido requires careful clinical monitoring before and during therapy.

• Hematocrit monitoring: check regularly to detect polycythemia.
• Prostate assessment: evaluate for benign prostatic hyperplasia before initiation.
• Cardiovascular risk: assess history of heart disease or thromboembolic events.
• Contraindicated in women of childbearing potential: avoid exposure due to androgenic effects.
• Liver function: monitor hepatic enzymes periodically.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Nebido can interact with several medication classes.

Major Interactions (Avoid)

• Warfarin: testosterone may enhance anticoagulant effect, increasing bleeding risk.
• Insulin: androgen therapy can alter glucose metabolism, requiring dose adjustments.
• Strong CYP3A4 inhibitors: may raise testosterone levels and increase adverse effects.

Moderate Interactions (Monitor Closely)

• Antihypertensives: fluid retention may blunt blood pressure control.
• Antidepressants: potential for mood alterations when combined.
• Other steroid hormones: additive androgenic effects may increase risk of side‑effects.