Cetrorelix (Cetrotide): IVF Dosing and Half-Life
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Cetrorelix: label dosing, mixing and half-life

Vial strength · Approval status · Half-life ~5 hours after one 0.25 mg dose (20.6 hours with repeated doses)

Short answer: Cetrorelix has a half-life of about 5 hours after one 0.25 mg dose (20.6 hours with repeated doses). Levels peak about 1 hour after a dose. People vary, so treat these as estimates.

What is cetrorelix?

Cetrorelix is a GnRH antagonist, a man-made peptide that blocks the GnRH receptor in the pituitary and quickly lowers LH and FSH. It is sold as Cetrotide (EMD Serono), a daily shot under the skin that stops an early LH surge (early ovulation) during IVF stimulation.

Also known as: Cetrotide, cetrorelix acetate.

Vial strength

Cetrotide comes as a 0.25 mg powder vial with a prefilled syringe of 1 mL sterile water, a 20 gauge needle for mixing and a 27 gauge needle for injecting. The solution is used right after mixing.

Approval status and how it is used

The Cetrotide label approves cetrorelix to prevent early LH surges in women having controlled ovarian stimulation. Label dosing is 0.25 mg under the skin of the lower belly once a day, starting on stimulation day 5 (morning or evening) or day 6 (morning), and continued until the day hCG is given; FSH or hMG starts on cycle day 2 or 3. In the studies the median length was 5 days. It is prescribed by fertility specialists, and women can self-inject after training.

The label has no boxed warning. It is not used with allergy to cetrorelix, mannitol or GnRH analogs, in pregnancy or breastfeeding, or with severe kidney impairment. Allergic reactions, including with the first dose, are the main precaution. In 949 women, moderate or severe OHSS was 3.5%, nausea 1.3% and headache 1.1%. Full numbers are on the Cetrotide side effects, Cetrotide dosing schedule and Cetrotide storage pages, and Cetrotide vs ganirelix compares the two antagonists.

Cetrorelix half-life and time to peak

  • Half-lifeabout 5 hours after one 0.25 mg dose (20.6 hours with repeated doses)
  • Time to peak (Tmax)about 1 hour

The Cetrotide label gives a median time to peak of 1 hour after a 0.25 mg injection under the skin. The half-life was 5.0 hours after a single 0.25 mg dose (range 2.4 to 48.8) and 20.6 hours after repeated daily doses (range 4.1 to 179.3), and 62.8 hours after a single 3 mg dose.

Numbers shown are taken from the source above. Half-life varies from person to person.

How to track cetrorelix in Dose Track

  1. Add cetrorelix as a custom compound. Start typing its name and Dose Track fills in the details from its research library for you to check, and it sits next to everything else you take.
  2. Log each daily injection when you give it, so your history lines up with your stimulation days and trigger shot.
  3. Set reminders on your own schedule, whether that is daily, weekly or every few days.
  4. Your log is stored on your phone and no account is needed. Data only leaves it for features you choose, like AI answers and lab reading.

How Dose Track handles peptides · Reconstitution calculator · Half-life calculator

Ganirelixganirelix acetate · half-life about 12.8 hours (16.2 hours with repeated doses) Follitropin (recombinant FSH)Gonal-f, Gonal-f RFF Redi-ject · half-life about 33 hours (Follistim AQ) to 53 hours (Gonal-f RFF) Menotropins (hMG)Menopur, hMG · half-life about 11 to 13 hours (FSH, repeated doses) LeuprolideLupron Depot, leuprorelin · half-life about 3 hours (after an IV dose)

Frequently asked questions

What is the half-life of cetrorelix?+
The Cetrotide label gives a median time to peak of 1 hour after a 0.25 mg injection under the skin. The half-life was 5.0 hours after a single 0.25 mg dose (range 2.4 to 48.8) and 20.6 hours after repeated daily doses (range 4.1 to 179.3), and 62.8 hours after a single 3 mg dose.
When is Cetrotide started in an IVF cycle?+
The label starts it on stimulation day 5 (morning or evening) or day 6 (morning) and continues it daily until the day of the hCG trigger.
How is cetrorelix different from leuprolide?+
Cetrorelix blocks the GnRH receptor and lowers LH and FSH right away. Leuprolide is a GnRH agonist that first raises them, then shuts them down over weeks.
Can I track cetrorelix in Dose Track?+
Yes. Cetrorelix is in Dose Track's research library, so when you add it as a custom compound its details are filled in for you to check. You can then log each injection next to your other compounds, set reminders on your own schedule, and see your history next to your lab results. Your log is stored on your phone and no account is needed. Data only leaves it for features you choose, like AI answers and lab reading.

Sources

  1. Cetrotide (cetrorelix acetate) for injection prescribing information (EMD Serono): indications, contraindications, precautions, adverse reactions, clinical pharmacology and dosage. DailyMed, September 2025.

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