Corifollitropin alfa
One injection in place of a week of daily FSH for IVF: human FSH fused to a fragment of hCG, authorised in the EU since 2010 and never approved in the US
Corifollitropin alfa (Elonva) is recombinant FSH whose β-subunit carries the C-terminal peptide of hCG's β-subunit, which slows its absorption and gives it a plasma half-life of about 65 hours. A single injection under the skin replaces the first seven days of daily FSH in IVF cycles that use a GnRH antagonist. In phase 3 trials it retrieved as many or more eggs than daily recombinant FSH, pregnancy and live-birth rates met non-inferiority margins, and ovarian hyperstimulation was about as common. The EU authorised it in January 2010; FDA has never approved it.
What is it?
Stimulating the ovaries for IVF usually means a week or more of daily FSH injections. Corifollitropin alfa was designed to replace the first week with one. It has the same α-subunit as FSH, and its β-subunit is FSH's with the C-terminal peptide of hCG's β-subunit attached; the result has FSH's activity with slower absorption and a plasma half-life of about 65 hours. One injection covers the first seven days of stimulation, after which daily FSH can be added if needed; in the trials about a third of women reached the trigger criterion on day 8 without it.
Two large double-blind phase 3 trials compared a single injection with seven daily injections of recombinant FSH in GnRH-antagonist cycles. The number of eggs retrieved was equivalent and ongoing pregnancy rates were non-inferior; in the trial of 396 women weighing 60 kg or less, a 100 µg dose retrieved 2.5 more eggs than daily FSH. A later trial in 1,390 women aged 35 to 42 found vital pregnancy rates of 23.9% against 26.9% and live-birth rates of 21.3% against 23.4%, differences within its non-inferiority margins, and a meta-analysis of eight trials and 4,340 cycles found no difference in live birth or ongoing pregnancy.
Its safety record comes from the same programme. Across the Engage and Ensure trials, ovarian hyperstimulation syndrome occurred in 6.9% of women on corifollitropin alfa and 6.0% on daily FSH (odds ratio 1.18), with more hospitalisations on corifollitropin alfa (1.9% against 0.9%). Follow-up of 838 fetuses found neonatal outcomes and malformation rates similar to daily FSH, and a thorough QT study in postmenopausal women found no effect on the heart's rhythm at therapeutic or supratherapeutic doses.
The EU authorised corifollitropin alfa as Elonva on January 25, 2010. It has never been approved in the US: FDA's Drugs@FDA database holds no application for it. It is a fertility medicine given in specialist clinics, not a product with any use outside assisted reproduction.
Mechanism of Action
Corifollitropin alfa acts on the FSH receptor like FSH itself. The difference is how long a single dose keeps acting.
FSH receptor agonist
It has the same pharmacological activity as FSH and recombinant FSH, stimulating the growth of multiple ovarian follicles; the rate of follicular development and the rise in inhibin B and oestradiol were similar to daily recombinant FSH.
hCG's C-terminal peptide
Attaching the C-terminal peptide of hCG's β-subunit to FSH's β-subunit produced a hybrid molecule with slower absorption and a prolonged elimination half-life, about 65 hours in plasma.
More follicles early
In a trial of 1,509 patients, follicles of 11 mm or more were slightly more numerous than on daily FSH by stimulation day 8 (difference 1.2) and on the day of the hCG trigger (difference 2.1).
Dose by body weight
The dose was set at 100 µg for women weighing 60 kg or less and 150 µg above 60 kg; in the lower-weight trial one injection was enough to reach the trigger criterion in 32.8% of women.
Published Research
These are the studies behind corifollitropin alfa, read from their PubMed abstracts: its phase 3 trials, pooled safety analyses, a meta-analysis and the reviews that describe the molecule. Nearly all enrolled women having IVF with a GnRH antagonist.
Women aged 35 to 42: 1,390 in a double-blind trial
A single 150 µg injection or daily 300 IU recombinant FSH for the first 7 days, then daily FSH as needed. Vital pregnancy rates per started cycle were 23.9% against 26.9% (difference -3.0%, 95% CI -7.4 to 1.4), eggs retrieved 10.7 against 10.3, and live births 21.3% against 23.4%, all non-inferior; serious adverse events occurred in 0.4% against 2.7%, and ovarian hyperstimulation in 1.7% of both groups.
Ensure: 396 women weighing 60 kg or less
Women were randomised 2:1 to one 100 µg injection or daily 150 IU recombinant FSH for the first 7 days. Eggs retrieved per started cycle were 13.3 against 10.6 (difference +2.5, 95% CI 1.2 to 3.9), within the equivalence margin; median stimulation was 9 days in both groups, one injection sufficed in 32.8%, and moderate or severe ovarian hyperstimulation occurred in 3.4% against 1.6%.
Pharmacokinetics and follicle growth in 1,509 patients
In a double-blind trial of 150 µg corifollitropin alfa against daily 200 IU recombinant FSH, follicular development proceeded at a similar rate; by day 8, 33% on corifollitropin alfa reached the hCG criterion. Follicles of 11 mm or more were slightly more numerous at day 8 (difference 1.2) and on the day of hCG (2.1), while inhibin B and oestradiol rose similarly.
Ovarian hyperstimulation across three trials
Of 1,705 women given corifollitropin alfa in the Engage, Ensure and Trust trials, 5.6% had mild, moderate or severe ovarian hyperstimulation syndrome. In the two randomised trials the pooled incidence was 6.9% against 6.0% on recombinant FSH (odds ratio 1.18, 95% CI 0.81 to 1.71), with hospitalisation in 1.9% against 0.9%.
838 fetuses followed up
Pooled follow-up of pregnancies from all phase 2 and 3 trials covered 677 pregnant women, 838 fetuses and 806 live-born infants. In the two randomised trials, any congenital malformation occurred in 16.3% against 17.0% and major malformations in 4.0% against 5.4% (odds ratio 0.71, 95% CI 0.36 to 1.38), with similar neonatal characteristics and premature births.
No effect on the QT interval
In a four-period crossover trial in healthy postmenopausal women, single doses of 150 µg and 240 µg were compared with moxifloxacin and placebo. The largest time-matched QTcF difference from placebo was 1.4 ms and 1.2 ms, with upper confidence limits below the regulatory threshold at every time point.
Meta-analysis: eight trials, 4,340 cycles
Across eight randomised trials, with 2,345 women on corifollitropin alfa and 1,995 on daily stimulation, live birth or ongoing pregnancy did not differ (risk ratio 0.92, 95% CI 0.80 to 1.05), nor did clinical pregnancy (0.96) or miscarriage (0.94).
The drug at approval
A fusion of FSH with the C-terminal peptide of hCG's β-subunit, with FSH's activity but slower absorption and a longer half-life. In two large double-blind phase 3 trials, one injection was as effective a multifollicular stimulant as seven daily injections of recombinant FSH: egg numbers were equivalent, ongoing pregnancy rates non-inferior, and median stimulation lasted 9 days in both arms.
Half-life, dosing and what the trials showed
The hybrid β-subunit gives a plasma half-life of about 65 hours. Across more than 2,500 women in trials, a third reached the hCG criterion on day 8 without extra gonadotropin; the optimal dose was calculated as 100 µg at 60 kg or less and 150 µg above, and outcomes were consistent over repeated cycles.
In development at Schering-Plough
Written during development, the profile describes the molecule's α-subunit identical to FSH's and a β-subunit fused to hCG's C-terminal peptide, giving a longer half-life that allows less frequent dosing; it was well tolerated without serious adverse events or antibody formation, and early phase 3 results showed ongoing pregnancy rates similar to daily recombinant FSH.
Dosing Data
Corifollitropin alfa is dosed by the fertility clinic within a stimulation protocol. The trials and its authorisation use a single dose chosen by body weight.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
Side Effects & Contraindications
Reported Side Effects
From the trials and pooled analyses above.
Contraindications & Cautions
From the trials; the clinic decides.
Legal Status
Corifollitropin alfa is authorised in the EU and not approved in the US.
Frequently Asked Questions
?How is corifollitropin alfa different from daily FSH?
It is FSH with a fragment of hCG attached to its β-subunit, which slows absorption and extends its half-life to about 65 hours. One injection replaces the first seven daily FSH injections of an IVF cycle.
?Does it work as well as daily FSH?
In phase 3 trials, egg numbers were equivalent or higher and pregnancy and live-birth rates met non-inferiority margins, and a meta-analysis of eight trials found no difference in live birth or ongoing pregnancy.
?Does it raise the risk of ovarian hyperstimulation?
About as often as daily FSH in the pooled trials (6.9% against 6.0%), but hospitalisation was more frequent (1.9% against 0.9%), and because the dose cannot be reduced once injected, clinics select patients carefully.
?Is corifollitropin alfa available in the US?
No. FDA's Drugs@FDA database holds no application for it. The EU authorised it as Elonva in January 2010.
?What dose is used?
In the trials, 100 µg for women weighing 60 kg or less and 150 µg for women over 60 kg, as a single injection under the skin on the first day of stimulation.
?Why is it on a peptide site?
It is a recombinant glycoprotein hormone built from peptide subunits, and it belongs beside the other gonadotropins in our encyclopedia. It has no use outside fertility treatment.
References
- [pubmed] Boostanfar R, et al. "Large, comparative, randomized double-blind trial confirming noninferiority of pregnancy rates for corifollitropin alfa compared with recombinant follicle-stimulating hormone in a gonadotropin-releasing hormone antagonist controlled ovarian stimulation protocol in older patients undergoing in vitro fertilization." Fertil Steril, 2015;104(1):94-103.e1. PMID: 26003273.
- [pubmed] "Corifollitropin alfa for ovarian stimulation in IVF: a randomized trial in lower-body-weight women." Reprod Biomed Online, 2010;21(1):66-76. PMID: 20483664.
- [pubmed] Fauser BC, et al. "Pharmacokinetics and follicular dynamics of corifollitropin alfa versus recombinant FSH during ovarian stimulation for IVF." Reprod Biomed Online, 2010;21(5):593-601. PMID: 20843746.
- [pubmed] Tarlatzis BC, et al. "Comparative incidence of ovarian hyperstimulation syndrome following ovarian stimulation with corifollitropin alfa or recombinant FSH." Reprod Biomed Online, 2012;24(4):410-9. PMID: 22386594.
- [pubmed] Bonduelle M, et al. "Prospective follow-up of 838 fetuses conceived after ovarian stimulation with corifollitropin alfa: comparative and overall neonatal outcome." Hum Reprod, 2012;27(7):2177-85. PMID: 22587997.
- [pubmed] de Kam PJ, et al. "Single therapeutic and supratherapeutic doses of corifollitropin alfa, a sustained follicle stimulant, do not prolong the QTcF-interval in healthy postmenopausal volunteers." Int J Clin Pharmacol Ther, 2015;53(9):772-82. PMID: 26227099.
- [pubmed] Cozzolino M, et al. "Corifollitropin alfa for ovarian stimulation in in vitro fertilization: a systematic review and meta-analysis of randomized controlled trials." Fertil Steril, 2019;111(4):722-733. PMID: 30929731.
- [pubmed] Croxtall JD, et al. "Corifollitropin alfa: a review of its use in controlled ovarian stimulation for assisted reproduction." BioDrugs, 2011;25(4):243-54. PMID: 21815699.
- [pubmed] Seyhan A, et al. "The role of corifollitropin alfa in controlled ovarian stimulation for IVF in combination with GnRH antagonist." Int J Womens Health, 2011;3:243-55. PMID: 21892335.
- [pubmed] Loutradis D, et al. "Corifollitropin alfa, a long-acting follicle-stimulating hormone agonist for the treatment of infertility." Curr Opin Investig Drugs, 2009;10(4):372-80. PMID: 19337959.
- [other] European Medicines Agency. Medicines register: Elonva (corifollitropin alfa), authorised; marketing authorisation date January 25, 2010. Read September 30, 2026.
- [fda] FDA. Drugs@FDA (openFDA): no application for corifollitropin alfa. Read September 30, 2026.
- [other] European Medicines Agency. Elonva (corifollitropin alfa): EPAR product information, Summary of Product Characteristics section 4.2 (read September 30, 2026).
Sources & Citations
Every study on this page was read from its PubMed record. Authorisation status comes from EMA's register and FDA's Drugs@FDA database, read September 30, 2026. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.