Nebido (Testosterone Undecanoate)

Nebido is used in testosterone replacement therapy to address conditions related to deficient androgen production.

• Male hypogonadism: restores normal testosterone concentrations, alleviating symptoms such as fatigue, reduced libido, and loss of muscle mass.
• Testosterone deficiency: improves energy levels, mood, and sexual function by supplementing endogenous hormone levels.
• Secondary hypogonadism: supports hormonal balance when the pituitary or hypothalamus fails to stimulate adequate testosterone production.

• Testosterone undecanoate is a long‑acting ester of testosterone that, after intramuscular injection, is slowly hydrolyzed to free testosterone. The resulting testosterone binds to intracellular androgen receptors, forming a hormone‑receptor complex that translocates to the nucleus and modulates androgen‑responsive gene transcription, thereby re‑establishing physiological androgenic activity in target tissues. Its depot formulation provides stable serum levels for several weeks, reducing the need for frequent dosing and maintaining consistent androgenic effects.

Nebido may be associated with a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Injection site pain
• Erythema or swelling at the injection site
• Headache
• Acne or oily skin

Serious or Rare Side Effects

• Polycythemia or elevated hematocrit
• Cardiovascular events such as myocardial infarction or stroke
• Prostate enlargement or exacerbation of prostate cancer
• Severe allergic reactions including anaphylaxis

Before initiating Nebido therapy, clinicians should evaluate several safety considerations to minimize risks.

• Assess prostate health: perform baseline PSA testing and digital rectal examination.
• Monitor hematocrit and hemoglobin: check levels periodically to detect polycythemia.
• Evaluate cardiovascular risk: review history of heart disease, hypertension, or thromboembolic events.
• Review liver function: conduct baseline liver enzyme tests and monitor during treatment.
• Check for hypersensitivity: avoid use in patients with known allergy to testosterone undecanoate or formulation excipients.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Nebido can interact with other medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Anticoagulants (e.g., warfarin): increased risk of thrombosis due to elevated hematocrit.
• Strong CYP3A4 inhibitors (e.g., ketoconazole): may raise testosterone levels and risk of adverse effects.
• Insulin or oral hypoglycemics: testosterone can affect glucose metabolism, requiring dose adjustments.

Moderate Interactions (Monitor Closely)

• Antihypertensive agents: testosterone may cause fluid retention, affecting blood pressure control.
• Statins: potential for altered lipid metabolism; monitor lipid profile.
• Other androgenic steroids: additive androgen effects may increase risk of side effects.