Histrelin
A GnRH agonist implant that suppresses puberty or testosterone for twelve months at a time
Histrelin is not taken; it is implanted. A hydrogel rod in the upper arm releases the peptide steadily for a year, holding hormones at castrate or prepubertal levels. Supprelin LA is approved for central precocious puberty; the prostate-cancer implant, Vantas, has been discontinued.
What is it?
Continuous GnRH agonist exposure does the opposite of pulsed exposure: it desensitises the pituitary and shuts off LH, and with it oestrogen or testosterone. Most agonists do that with injections every one to six months; histrelin's implant does it with one minor procedure a year, releasing about 65 µg a day according to the Supprelin LA label.
In central precocious puberty the suppression is quick and deep. In a 36-child phase 3 study, peak LH after stimulation testing fell from 28.2 to 0.8 mIU/mL within a month. The extension followed the same children for up to six years: suppression held, and predicted adult height in girls rose from 151.9 cm to 166.5 cm. In children whose early puberty came from congenital adrenal hyperplasia, predicted adult height rose by about 7 cm.
The label says to remove it after 12 months, noting it is designed to release drug for a few weeks longer to allow flexible appointments. In practice many are kept much longer: in one series implants stayed in for an average of 24 months, and in another most still suppressed puberty at about three years, though escape began from 15 months in some. In three girls, retained fragments kept puberty suppressed for up to five years.
The procedure itself is small. Most insertions and removals in one centre were done in clinic without sedation; younger children more often needed it, and complications were more likely the longer an implant had been in. In US claims data, children stayed on histrelin longer than on leuprolide injections, at a lower annual cost.
The prostate-cancer use aims the same mechanism at testosterone. In 134 men, every patient with a week-4 measurement reached castrate testosterone and over 99% stayed there through 52 weeks, with PSA down 90% by week 16. An extension ran annual implants for over four years; a dose study found one implant as good as four. That product, Vantas, is now listed as discontinued.
It is also used to pause puberty in young people with gender dysphoria, where a comparison found the two implant strengths suppressed hormones equally. That use is outside the label.
Mechanism of Action
Histrelin is a GnRH agonist delivered continuously from an implant, which switches off the pituitary's drive to the sex glands.
GnRH receptor
A potent GnRH agonist; after an initial surge, continuous exposure desensitises pituitary GnRH receptors.
LH and FSH suppressed
Peak stimulated LH fell from 28.2 to 0.8 mIU/mL within a month in the phase 3 trial.
Steady release
The 50 mg implant releases about 65 µg a day for 12 months, with a few weeks' margin (label 2.1).
Published Research
These are the trials that describe histrelin, read from their PubMed abstracts: two in children with precocious puberty and one in men with prostate cancer.
Phase 3 in central precocious puberty
36 children at nine US centres received one 50 mg implant for a year. Peak LH after stimulation fell from 28.2 to 0.8 mIU/mL in treatment-naive children and from 2.1 to 0.5 in previously treated ones; oestradiol fell from 24.5 to 5.9 pg/mL.
Six years of yearly implants
The same 36 children continued with a new implant each year for up to six years. Suppression held in both naive and previously treated children, the bone-age ratio fell from 1.42 to 1.18, and predicted adult height in girls rose from 151.9 cm to 166.5 cm.
Advanced prostate cancer
134 men received a 50 mg implant for 52 weeks. Every man with a week-4 measurement reached castrate testosterone, over 99% stayed there to week 52, and PSA fell an average 90% by week 16.
Implant against leuprolide injections
In US claims data on 4,217 children with precocious puberty, treatment lasted longer on the implant than on leuprolide (26.7 against 14.1 months), at lower annual cost.
Keeping one implant longer
In 50 pediatric patients, 42 implants kept puberty suppressed throughout, averaging 37.5 months; 8 escaped at about 30 months.
One implant beyond a year
In children with central precocious puberty whose implants stayed in place an average of 24 months, puberty regressed or stayed stable and hormones stayed suppressed in the great majority; time in place did not predict breakage or a second incision.
Placed in clinic without sedation
Of 184 implant procedures in 73 patients, 82% were done in clinic without sedation; younger age predicted needing sedation, and complications (5%) were more likely when an implant had been in longer (21 against 13 months).
A fragment left behind
Case series: in three girls, a piece of implant that broke during removal and stayed in the arm, or an implant never removed, kept puberty suppressed for up to five years.
Congenital adrenal hyperplasia
In 15 children with congenital adrenal hyperplasia and early puberty treated for a median of 3 years, bone-age advance slowed and predicted adult height rose by 7.1 cm; adult height improved but stayed below mid-parental height.
The two implant strengths compared
In 66 young people with gender dysphoria, the 50 µg/day (Vantas) and 65 µg/day (Supprelin LA) implants suppressed gonadotropins and sex steroids equally at 2 to 12 months.
Dosing Data
Supprelin LA is one 50 mg implant placed under the skin of the inner upper arm, replaced every 12 months.
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Side Effects & Contraindications
Reported Side Effects
From the Supprelin LA label and the trials above.
Contraindications & Cautions
A prescription implant inserted and removed by a clinician.
Legal Status
Histrelin is approved in the US as Supprelin LA; the prostate-cancer implant has been discontinued.
Frequently Asked Questions
?What is histrelin?
A nine-amino-acid GnRH agonist delivered by a hydrogel implant under the skin of the upper arm, releasing it steadily for twelve months.
?What is it approved for?
Central precocious puberty in children, as Supprelin LA. The prostate-cancer implant, Vantas, is listed as discontinued.
?How well does it suppress hormones?
Deeply. Peak LH in children fell from 28.2 to 0.8 mIU/mL within a month, and over 99% of men stayed at castrate testosterone through a year.
?Does the dose matter?
Apparently not above a threshold. With one, two or four implants, blood levels rose with number but testosterone suppression was the same.
References
- [fda-pi] Supprelin LA (histrelin acetate) subcutaneous implant Prescribing Information, sections 1 and 2. Endo USA (DailyMed version 38, effective September 25, 2025; read September 30, 2026).
- [pubmed] Eugster EA, et al. "Efficacy and safety of histrelin subdermal implant in children with central precocious puberty: a multicenter trial." J Clin Endocrinol Metab, 2007;92(5):1697-704. PMID: 17327379.
- [pubmed] Silverman LA, et al. "Long-Term Continuous Suppression With Once-Yearly Histrelin Subcutaneous Implants for the Treatment of Central Precocious Puberty: A Final Report of a Phase 3 Multicenter Trial." J Clin Endocrinol Metab, 2015;100(6):2354-63. PMID: 25803268.
- [pubmed] Schlegel PN. "Efficacy and safety of histrelin subdermal implant in patients with advanced prostate cancer." J Urol, 2006;175(4):1353-8. PMID: 16515997.
- [pubmed] Shore N, et al. "Long-term efficacy and tolerability of once-yearly histrelin acetate subcutaneous implant in patients with advanced prostate cancer." BJU Int, 2012;109(2):226-32. PMID: 21851539.
- [pubmed] Schlegel PN, et al. "Effective long-term androgen suppression in men with prostate cancer using a hydrogel implant with the GnRH agonist histrelin." Urology, 2001;58(4):578-82. PMID: 11597543.
- [other] US FDA, Drugs@FDA (openFDA): SUPPRELIN LA, NDA 022058, Endo, prescription; VANTAS, NDA 021732, Discontinued. Read September 30, 2026.
- [pubmed] Silverman LA, et al. "Clinical characteristics and treatment patterns with histrelin acetate subcutaneous implants vs. leuprolide injections in children with precocious puberty: a real-world study using a US claims database." J Pediatr Endocrinol Metab, 2021;34(8):961-969. PMID: 34147047.
- [pubmed] Pine-Twaddell E, et al. "Extended Use of Histrelin Implant in Pediatric Patients." Transgend Health, 2023;8(3):264-272. PMID: 37342480.
- [pubmed] Ray LA, et al. "Long-term experience with the use of a single histrelin implant beyond one year in patients with central precocious puberty." J Pediatr Endocrinol Metab, 2023;36(3):309-312. PMID: 36625262.
- [pubmed] Krishna V, et al. "Optimizing pediatric histrelin implantation to improve success rates in clinic without sedation." J Pediatr Endocrinol Metab, 2021;34(11):1443-1448. PMID: 34407329.
- [pubmed] Marpuri I, et al. "Prolonged Pubertal Suppression due to Retained Histrelin Implant in Three Children with Central Precocious Puberty." Horm Res Paediatr, 2026;99(5):642-646. PMID: 40015262.
- [pubmed] Swendiman RA, et al. "Histrelin Implantation and Growth Outcomes in Children With Congenital Adrenal Hyperplasia: An Institutional Experience." J Endocr Soc, 2020;4(2):bvz004. PMID: 32104750.
- [pubmed] Olson-Kennedy J, et al. "Histrelin Implants for Suppression of Puberty in Youth with Gender Dysphoria: A Comparison of 50 mcg/Day (Vantas) and 65 mcg/Day (SupprelinLA)." Transgend Health, 2021;6(1):36-42. PMID: 33644320.
- [fda-pi] Supprelin LA (histrelin acetate) subcutaneous implant US prescribing information (Endo; DailyMed set d8fb000e, effective September 25, 2025), section 2.1; read through openFDA October 6, 2026.
Sources & Citations
Studies were read from their PubMed abstracts; the Supprelin LA label from DailyMed (set d8fb000e, effective September 25, 2025) through openFDA, read October 6, 2026.
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