Triptorelin vs leuprolide: GnRH agonists compared

Triptorelin and leuprolide are both FDA-approved GnRH agonists. Their labels overlap in advanced prostate cancer and central precocious puberty, and differ in formulations, injection route and extra uses. Both cause a temporary rise in sex hormones before they suppress them.

Side by side

GnRH stands for gonadotropin-releasing hormone, the brain signal that starts the body’s sex-hormone chain. Triptorelin and leuprolide are lab-made versions of it. Triptorelin’s label calls it a decapeptide (ten amino acids); leuprolide’s calls it a nonapeptide (nine).¹³ The table shows what each current US label says. Dose strengths are left out on purpose.

Two points follow from the table. First, “leuprolide” is not one product: its brands differ in route and schedule. Second, only the leuprolide labels listed include endometriosis and fibroids; the triptorelin labels listed do not.

Same mechanism

The leuprolide label says that after an initial stimulation, continuous administration suppresses ovarian and testicular steroidogenesis (the making of sex hormones), based on animal studies.³ The Triptodur label describes the same pattern in people: a transient surge in LH, FSH, testosterone and estradiol after the first dose, then a sustained decrease in LH, FSH and sex steroids by four weeks.² The Trelstar label reports that, in laboratory studies of rat pituitary cells, triptorelin was 100-fold more active than the body’s own GnRH at stimulating LH release.¹ That is a laboratory potency figure, not a measure of how well the medicine works in patients.

The early hormone rise

All three prostate-cancer labels describe a temporary testosterone increase when treatment starts, and tell clinicians to watch for worsening symptoms in the first weeks:

• Trelstar: a transient rise in testosterone, with possible worsening of bone pain, neuropathy, blood in the urine, or urinary obstruction in the first weeks; patients with metastatic vertebral lesions or urinary obstruction are to be monitored closely.¹
• Lupron Depot: testosterone about 50% above baseline may occur at the start; the label warns of bone pain, neuropathy, hematuria, ureteral obstruction and spinal cord compression.³
• Eligard: a transient rise during the first week of treatment for the lower strengths, and during the first two weeks for the 45 mg strength.⁴

This is a safety feature of the whole drug class, not a difference between triptorelin and leuprolide.

Warnings the labels share

The Trelstar and Lupron Depot labels both warn that GnRH agonists may cause metabolic changes (high blood sugar, diabetes, high blood lipids, and non-alcoholic fatty liver disease), and that heart attack, sudden cardiac death and stroke have been reported in men taking them.¹³ The labels tell clinicians to monitor for these. Read the full current label of whichever product applies.

What this comparison cannot tell you

• It compares labels, not outcomes. Each label reports its own studies. These are not head-to-head trials, so nothing here says that one medicine works better than the other.
• Choosing a product is a clinical decision. Cancer stage, other conditions, injection schedule and cost all matter. A prescriber makes that choice, not a web page.
• These are provider-administered medicines. The labels say they are given by or under the supervision of a healthcare provider.¹²³⁴ A vial sold online under either name is not one of these approved products; see what “Research Use Only” actually means.

For each medicine alone, including the approval history and the 2010 FDA class warning, see triptorelin and leuprolide.

As of this review