Acyline

Summary

Acyline is a third-generation synthetic GnRH antagonist peptide developed by the National Institutes of Health (NIH) and the Contraceptive Development Program. It has been studied primarily as a male contraceptive agent and for suppression of sex steroids in various clinical research contexts. It produces rapid, reversible suppression of gonadotropins and testosterone without the flare effect. It has not been approved for clinical use.

Mechanism of Action

Competitively binds to gonadotropin-releasing hormone (GnRH) receptors in the pituitary gland, blocking endogenous GnRH signaling and rapidly suppressing LH and FSH secretion, thereby reducing gonadal steroid production without the initial hormonal flare seen with GnRH agonists.

Routes of Administration

Goals & Uses

• Precocious puberty treatment (research)Pediatric EndocrinologyLow
• Research tool for HPG axis studiesResearchHigh
• Testosterone suppressionOncology/EndocrinologyModerate
• Male contraceptionReproductive EndocrinologyModerate
• Suppression of gonadotropins (LH/FSH)EndocrinologyModerate

Contraindications

• PregnancyPopulationHighPotential fetal risk or insufficient safety data
• Hypersensitivity to GnRH analoguesAllergy/ImmunologyHigh
• Osteoporosis or significant bone lossMusculoskeletalModerate

Adverse Effects

• Mood changesPsychiatricUncommon
• Injection site reactionsLocalCommon
• HeadacheNeurologicUncommonPain in the head or upper neck
• Hypogonadism symptoms (hot flashes, reduced libido)Endocrine/ReproductiveCommon
• Bone mineral density reductionMusculoskeletalUncommon

Drug Interactions

• Other GnRH analoguesModerate
• Testosterone (exogenous)Low

Population Constraints

• Pediatric patientsAgeRelative
• Patients with pre-existing cardiovascular diseaseCardiovascularRelative
• Postmenopausal womenReproductive StatusRelative

Regulatory Status

• European UnionUnknownNo EMA submission or approval on record; used only in research settings.
• United StatesInvestigationalStudied under IND in NIH-sponsored trials; not FDA-approved for any indication.
• United KingdomUnknownNo MHRA approval; research use only.

Acyline has not received FDA, EMA, or other regulatory approval. It remains an investigational compound used in NIH-sponsored and academic clinical trials. Synthesized under research protocols; not commercially available.

Evidence & Sources

No sources recorded yet.