# Cetrorelix: track every shot, units to draw and what's still active

> Reconstitution calculator, as needed schedule, site rotation and half-life chart for Cetrorelix. Track it in Peppy, private on your iPhone.

Source: https://peppytracker.com/compounds/cetrorelix/
Last updated: 2026-09-02

GnRH receptor antagonist branded as Cetrotide; FDA-approved to prevent premature LH surges during controlled ovarian stimulation in IVF. In the Peppy catalog, Cetrorelix is reconstituted from a vial and drawn up in units on an insulin syringe, dosed in mg, typically as needed, with a listed half-life of about 30 hours.

## Frequently asked

### How many units is 0.25 mg of Cetrorelix?

It depends on how the vial was mixed. Example: a 5 mg vial plus 2 mL of bacteriostatic water is 2.5 mg/mL, so 0.25 mg is 0.1 mL, or **10 units** on a U-100 insulin syringe. Change the water and the units change. Use the calculator above with your own vial, and verify with your prescriber.

### How long does Cetrorelix stay in your system?

The Peppy catalog lists a half-life of about 30 hours for Cetrorelix. After roughly five half-lives, about 6.2 days, most of a single dose has cleared. That is an estimate from the half-life, not a measurement, and individual clearance varies.

### Can I track Cetrorelix in Peppy?

Yes. Cetrorelix is one of 123 compounds built into Peppy, with its form, unit and typical frequency prefilled. Add it as a protocol, set your schedule, and Peppy handles the countdown, the log and the reminders (Pro).

### Where should I inject Cetrorelix?

Follow your prescriber's instructions. For subcutaneous shots the GLP-1 labels list the abdomen, thigh and upper arm and say to rotate. Peppy's body map has 13 sites, suggests the next one, and shows when each was last used. Read the [site rotation guide](https://peppytracker.com/guides/injection-site-rotation/).

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Peppy is a tracking tool, not medical advice. Dose calculations are mathematical conversions only. Always follow your prescriber's instructions and verify every draw-up yourself.

Peppy is a free iPhone app (Pro subscription optional). App Store: https://apps.apple.com/us/app/peptide-tracker-peppy/id6775005514