GnRH agonist (gonadorelin analogue)
Pregnancy: Contraindicated — anovulation effect; spontaneous miscarriage if pregnancy occurs early in IVF cycle.
Buserelin
Brand names: Suprefact, Suprecur
Adult dose
Dose: Prostate cancer (Suprefact): 500 mcg SC every 8 hours for 7 days, then 200 mcg intranasal every 8 hours (one spray each nostril). Endometriosis (Suprecur nasal): 150 mcg (1 spray) into each nostril TDS for max 6 months. IVF down-regulation (Suprefact): 0.5 mg SC OD (long protocol), starting mid-luteal phase.
Route: Subcutaneous / Intranasal
Frequency: TDS (nasal) or OD (SC)
Initial flare in prostate cancer — co-administer anti-androgen (cyproterone or bicalutamide) for first 2–3 weeks to prevent tumour-flare.
Clinical pearls
- Mechanism: continuous stimulation desensitises pituitary GnRH receptors → suppresses LH/FSH → chemical castration in 2–4 weeks.
- Prostate cancer 'tumour flare' is preventable by anti-androgen 7 days BEFORE buserelin start, continuing for 2–3 weeks.
- Bone protection: DEXA at baseline; calcium + vitamin D + bisphosphonate or denosumab if treatment >6 months.
- Endometriosis: limit to 6 months without 'add-back' HRT (tibolone or low-dose oestrogen-progestogen) to protect bone.
- IVF long protocol: down-regulation confirmed by oestradiol <50 pmol/L and endometrium <5 mm before stimulation.
- GnRH antagonists (degarelix, cetrorelix) avoid the initial flare and are increasingly preferred in prostate cancer.
Contraindications
- Pregnancy and breastfeeding
- Hormone-independent prostate cancer (no benefit)
- Undiagnosed vaginal bleeding
- Hypersensitivity to GnRH analogues
Side effects
- Hot flushes (very common)
- Initial 'flare' in prostate cancer — bone pain, ureteric obstruction, spinal cord compression (CRITICAL — co-prescribe anti-androgen)
- Loss of libido, erectile dysfunction (men); vaginal dryness, dyspareunia (women)
- Mood changes, depression
- Bone mineral density loss with prolonged use (>6 months)
- Injection-site reactions
- Nasal irritation (intranasal)
- QT prolongation (class effect)
- Pituitary apoplexy (rare — caution with adenoma)
Interactions
- Antidiabetic agents: ↑ insulin resistance — adjust glycaemic therapy
- QT-prolonging drugs (amiodarone, citalopram, methadone): additive QT prolongation
Monitoring
- Testosterone (prostate cancer — should be castrate <0.7 nmol/L)
- DEXA at baseline and 1 yearly if prolonged
- BMI, BP, glucose annually
- Mood/PHQ-9
Reference: BNF 90; SmPC Suprefact / Suprecur; NICE NG131 (Prostate cancer); ESHRE IVF Guidelines. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.