data + articles · 1 listed
newest 2004spec sheet8 rows
Acyline is a potent synthetic decapeptide gonadotropin-releasing hormone (GnRH) antagonist studied for reversible suppression of the hypothalamic-pituitary-gonadal axis, including as a potential male hormonal contraceptive.
- Studied as a potential reversible male hormonal contraceptive by suppressing testosterone production
- Used as a research tool to study the hypothalamic-pituitary-gonadal axis
- Investigated in veterinary research to prevent ovulation and estrus in animals
- Mild injection-site reactions (redness, itching) were the most commonly reported adverse events in human studies
Overview
One of the more convincing male-contraceptive research candidates; a single injection can suppress testosterone to castrate levels for about two weeks.
Mechanism
Acyline competitively blocks the GnRH receptor on pituitary gonadotrope cells, preventing endogenous GnRH from stimulating the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Because LH and FSH drive gonadal hormone production, this suppresses downstream testosterone (or ) output. A single injected dose has suppressed gonadotropins and testosterone to castrate levels for roughly two weeks in healthy men.
receptor fingerprint
GnRH receptorAntagonist
Dosingtypical ranges, not medical advice
interested in protocols and clinical dosages? make an account to see them! ^_^
Safetyrisks and cautions, not medical advice
In Phase I/II human studies, acyline was generally well tolerated, with mild injection-site reactions (erythema and pruritus) reported as the most common adverse events. Because it is a peptide, it is poorly absorbed orally; an enteric-coated oral formulation (MER-104) using absorption-enhancing technology was developed and tested in dose-ranging studies. Long-term safety data in broad populations are limited, as it has not been approved as a marketed drug.
Subjective profileweighing the evidence above
It did exactly what it was designed to do, dropping gonadotropins and testosterone to castrate levels for about two weeks from a single injection, and it was well tolerated in small trials. That makes it a research probe, not a product; nobody outside a study has a reason to induce experimental hypogonadism.
Resources
This entry is here for reference.
Research
1 listed here; entry last updated July 2026
Reviews
My notesprivate to this device
FAQ
What is Acyline used for?
It has no approved medical use yet. It has been studied mainly as a potential male hormonal contraceptive and as a research tool for suppressing the hypothalamic-pituitary-gonadal hormone axis.
How does Acyline work?
It blocks the GnRH receptor in the pituitary gland, which stops the release of luteinizing hormone and follicle-stimulating hormone, and in turn suppresses testosterone production.
Is Acyline well-researched?
It has gone through Phase I and Phase II human studies showing effective, reversible hormone suppression, but it has not been approved or brought to market.
Adverse effects
- Mild injection-site reactions (redness, itching) were the most commonly reported adverse events in human studies
Notes and cautions
- As a peptide, it requires injection or a specialized oral formulation because it is poorly absorbed in its native form
- Not approved as a marketed drug; remains a research and investigational compound