Triptorelin

How it works

As a GnRH agonist it initially stimulates and then, with continuous administration, downregulates pituitary GnRH receptors, suppressing luteinising hormone and follicle-stimulating hormone release and so reducing testosterone or oestrogen production to castrate or postmenopausal levels.

Prescribing in practice

• In men with prostate cancer the initial testosterone surge can cause a temporary tumour flare, which may worsen bone pain or cause spinal cord compression or urinary obstruction, so anti-androgen cover should be considered, especially with metastatic disease.
• Long-term use reduces bone mineral density, so bone health should be considered with prolonged treatment.
• It must not be used in pregnancy, and prolonged use causes hypo-oestrogenic effects in women that may need addition of add-back therapy.

Monitoring

Monitor the relevant hormonal response (testosterone or oestrogen and, in prostate cancer, PSA), bone mineral density with prolonged use, and clinical disease response.

Counselling the patient

• This is given as a depot injection at regular intervals by a healthcare professional.
• Men may notice a brief worsening of symptoms when starting; report new or worsening bone pain, weakness, or trouble passing urine.
• Hot flushes and reduced libido are common; women may have menopause-like symptoms.

Evidence & guidelines

Efficacy across its hormone-dependent indications is supported by randomised trials and extensive clinical experience with GnRH agonist therapy.