Histrelin (Supprelin LA / Vantas)

Prescription

Histrelin acetate is a synthetic nonapeptide GnRH agonist notable for its delivery system: a small hydrogel implant, placed under the skin of the upper arm, that releases drug steadily for a full 12 months. This makes it one of the longest single-dose intervals of any peptide therapeutic. Two brands use the same molecule at different doses — Supprelin LA for central precocious puberty in children, and Vantas for palliative treatment of advanced prostate cancer in adults. Structurally, histrelin carries the D-histidine(benzyl) substitution at position 6 and a C-terminal modification that increase potency and metabolic stability. Its pharmacology is the familiar GnRH-agonist paradox: continuous, non-pulsatile receptor stimulation first stimulates and then, within a couple of weeks, downregulates and desensitizes the pituitary GnRH receptor, suppressing LH and FSH and therefore sex-steroid production. In central precocious puberty, the yearly implant is a major convenience advantage: children avoid monthly injections, and one minor in-office procedure provides a year of suppression, pausing premature puberty and protecting adult height. In advanced prostate cancer, the implant delivers continuous androgen deprivation for a year, sparing patients frequent depot injections. The implant is removed (and, if therapy continues, replaced) at the end of each 12-month period. The expected effects mirror other GnRH agonists — hot flashes, reduced libido and bone density in adults; an early transient flare; and, in children, careful monitoring to confirm adequate suppression. Because insertion and removal are minor surgical procedures, local implant-site issues (soreness, and occasionally difficulty locating the implant at removal) are specific practical considerations. Treatment is managed by a pediatric endocrinologist or urologist/oncologist.