Iturelix
Also known as: Cetrorelix analogue, D-63153, Iturel
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Summary
Iturelix (also known as antide or D‑63153) is an investigational decapeptide GnRH antagonist studied for use in assisted reproduction. In early‑phase clinical trials it was given subcutaneously to women undergoing IVF/ICSI to suppress premature luteinising hormone (LH) surges and to optimise hormonal conditions for embryo implantation.
Mechanism of Action
Iturelix binds competitively to gonadotropin‑releasing hormone (GnRH) receptors on pituitary gonadotrophs, blocking the endogenous GnRH signal. This inhibition reduces the pulsatile release of LH (and to a lesser extent FSH), preventing the premature LH surge that can trigger ovulation before oocyte retrieval. By modulating LH and downstream progesterone production, the antagonist helps maintain a controlled ovarian stimulation environment.
What the Research Shows
Two prospective, single‑centre dose‑finding studies enrolled 144 IVF/ICSI patients each and evaluated daily subcutaneous Iturelix from stimulation day 6 or 7. Hormone monitoring showed dose‑dependent reductions in LH and estradiol, with a minimal effective concentration identified at 0.5 mg ml⁻¹, which prevented LH surges in >97 % of cycles. Clinical pregnancies occurred only when LH and progesterone changes fell within defined ranges; excessive suppression or insufficient control correlated with lower pregnancy rates. The drug was reported as well tolerated in these short‑term studies.
Reported Benefits
Evidence from the trials suggests Iturelix can reliably prevent premature LH surges during controlled ovarian stimulation, allowing clinicians to schedule oocyte retrieval without the risk of early ovulation. By maintaining LH and progesterone within optimal windows, the antagonist may improve the likelihood of achieving a clinical pregnancy in IVF cycles.
Limitations of the Evidence
Findings are limited to two small, single‑centre studies without long‑term follow‑up or direct comparison to other GnRH antagonists. Sample sizes were modest, and pregnancy outcomes were linked to hormone ranges rather than a direct efficacy endpoint. Safety data are restricted to the trial period, and broader population effects remain unknown.
Safety Considerations
Both studies reported that Iturelix was overall well tolerated, with no serious adverse events noted during the treatment window. Specific side‑effects were not detailed in the abstracts, and the short duration of exposure limits conclusions about longer‑term safety. As an investigational agent, comprehensive safety profiling is still required.
How It Is Administered
Iturelix is administered as a subcutaneous injection once daily, typically beginning on stimulation day 6 or 7 of an IVF protocol. Formulations evaluated in the studies included concentrations of 2 mg / 2 ml, 1 mg ml⁻¹, 0.5 mg ml⁻¹ (the minimal effective dose), and 0.25 mg ml⁻¹, delivered in volumes ranging from 0.5 to 2 ml.
Routes of Administration
Goals & Uses
- Suppression of LH and FSHEndocrineModerate
- Testosterone suppressionOncology/EndocrinologyModerate
- Prostate cancer hormone therapyOncologyLow
- Treatment of benign prostatic hyperplasia (BPH)UrologyModerate
Contraindications
- Pre-existing severe hepatic impairmentHepaticModerate
- PregnancyPopulationHighPotential fetal risk or insufficient safety data
- Hypersensitivity to GnRH or GnRH analoguesAllergy/immunologyHigh
Adverse Effects
- Allergic reactionsImmunologicalRare
- Injection site reactionsLocalCommon
- Hot flashesEndocrine / VasomotorCommon
- Bone density reductionMusculoskeletalUncommon
- Sexual dysfunction / decreased libidoEndocrine/sexualCommon
Drug Interactions
- Anticoagulants (e.g., warfarin)Low
- QT-prolonging agentsModerate
Population Constraints
- Pediatric populationsAgeRelative
- Patients with pre-existing cardiovascular diseaseCardiovascularRelative
- Women of childbearing potentialReproductiveAbsolute
Regulatory Status
- European UnionInvestigationalInvestigated in European clinical settings but not approved by EMA.
- United StatesInvestigationalNever received FDA approval; evaluated in early-phase clinical trials only.
- United KingdomUnknownNo known MHRA approval or formal regulatory review record.
Iturelix has not received approval from the FDA, EMA, or other major regulatory agencies. It has been evaluated in clinical trials but did not advance to approved status.
Evidence & Sources
- Journal ArticleModerateHuirne JA, et al.2005-01-01T00:00:00.000000Z
- Journal ArticleModerateHuirne JA, et al.2004-01-01T00:00:00.000000Z
Frequently Asked Questions
What is the purpose of using Iturelix in IVF?
Iturelix is used to block the GnRH receptor, preventing the natural LH surge that can cause premature ovulation. By controlling LH levels, clinicians can better coordinate oocyte retrieval and improve the hormonal environment for implantation.
How is the optimal dose of Iturelix determined?
Dose‑finding studies identified 0.5 mg ml⁻¹ as the lowest concentration that prevented LH surges in the majority of patients while maintaining acceptable hormone profiles. Doses lower than this showed a higher incidence of LH spikes.
Are there any known side effects of Iturelix?
The published trials reported that the drug was well tolerated, and no serious adverse events were described. However, detailed side‑effect information was not provided, and longer‑term safety has not been established.
Can Iturelix be used for purposes other than IVF?
Current research has focused exclusively on its use in IVF/ICSI cycles to prevent premature LH surges. No evidence from the cited studies supports use in other reproductive or endocrine indications.
Is Iturelix approved for clinical use?
Iturelix remains investigational and has not received regulatory approval for any indication. Its use is confined to clinical research settings.
What is Iturelix used for?
Iturelix is educationally associated with: Suppression of LH and FSH, Testosterone suppression, Prostate cancer hormone therapy, Treatment of benign prostatic hyperplasia (BPH). Educational only — not medical advice.
How is Iturelix administered?
Recorded routes of administration: Subcutaneous.
What are the potential side effects of Iturelix?
Reported adverse effects include: Allergic reactions, Injection site reactions, Hot flashes, Bone density reduction, Sexual dysfunction / decreased libido. This list is not exhaustive — consult a qualified clinician.
Who should avoid Iturelix?
Recorded contraindications: Pre-existing severe hepatic impairment, Pregnancy, Hypersensitivity to GnRH or GnRH analogues. Consult a qualified clinician before use.