BuserelinvsLeuprolide

Molecular Formula

C₆₀H₈₆N₁₆O₁₃

Molecular Weight

1239.4 g/mol

Half-Life

2-4 hours (subcutaneous), 30-60 minutes (intranasal); longer for depot formulation (28-40 days)

Bioavailability

~1% (oral); ~10-15% (intranasal); ~95% (subcutaneous)

CAS Number

57773-65-6

Molecular Formula

C₅₉H₈₄N₁₆O₁₂

Molecular Weight

1209.4 g/mol

Half-Life

Approximately 2-6 hours (varies by route of administration)

Bioavailability

~95% (subcutaneous injection)

CAS Number

74381-53-6

Common

• Hot flashes (very common in men)
• Decreased libido and erectile dysfunction
• Injection site pain or swelling
• Nausea
• Fatigue
• Mood changes or depression
• Joint or muscle pain
• Headaches
• Dizziness
• Thinning hair
• Decreased bone density (osteoporosis with long-term use)
• QT prolongation (rare but serious cardiac effect)
• Tumor flare (temporary worsening of cancer symptoms in first weeks)
• Severe allergic reactions
• Spinal cord compression risk in men with metastatic disease

Serious

• Severe allergic reaction

Evidence Level

Strong human trials (Phase 3 or FDA approved)

FDA Status

FDA approved for other use

Safety Overview

Buserelin is an FDA-approved GnRH agonist with safety data from Phase 3 trials and decades of clinical use, but carries well-documented risks from intentional testosterone/estrogen suppression. The initial testosterone flare (first 2-3 weeks) can worsen prostate cancer symptoms and cause tumor flare pain in 10-20% of patients. Long-term use causes bone density loss of 2-3% annually, with vertebral fractures in 10-20% of long-term users. Cardiovascular risks include increased MI and stroke in men over 65. Hot flashes affect 40-80%, erectile dysfunction is nearly universal, and liver enzyme elevations occur in 5%. Nasal spray formulation causes local irritation in 20-30% of users.

Contraindications

• xPregnancy or breastfeeding
• xHypersensitivity to GnRH agonists
• xCertain bone diseases when long-term use is planned

Evidence Level

Strong human trials (Phase 3 or FDA approved)

FDA Status

FDA approved for this use

Safety Overview

Leuprolide (Lupron) is an FDA-approved GnRH agonist with 35+ years of clinical safety data involving millions of patients in oncology and endocrinology. The critical safety issue is the initial 5-7 day flare effect—temporary surge in FSH/LH causing symptom worsening before hormone suppression begins—particularly dangerous for prostate cancer patients (flare can cause urinary obstruction or spinal cord compression). Bone density loss is a dose-dependent long-term risk in both men and women requiring monitoring. Injection site reactions, hot flushes, and initial hypogonadal symptoms are expected and typically transient.

Contraindications

• xPregnancy or breastfeeding (teratogenic)
• xUndiagnosed vaginal bleeding
• xActive bone metastases with spinal cord compression (increased fracture risk)
• xAllergy to GnRH agonists or components
• xSevere cardiovascular disease with QT prolongation risk