Implant stalls puberty 5 years or more

The subdermal once-yearly implant containing the gonadotropin-releasing hormone agonist (GnRHa) histrelin (Supprelin LA) delays puberty in children with central precocious puberty for up to 5 years and perhaps longer.

A small cohort study, presented as a poster session at the 2013 meeting of the Pediatric EndocrineSociety held in Washington, DC, earlier this month, finds that up to 5 years of continuous therapy with the 50-mg implant is effective and well tolerated in suppressing the hypothalamic-pituitary-gonadal (HPG) axis in children with the condition.

The study, involving 36 children aged between 2 and 11 years, shows that levels of 2 hormonal markers of puberty-luteinizing hormone (LH) and follicle-stimulating hormone (FSH)-were mere fractions of baseline levels after 5 years of implant use.

In addition, through 5 years of therapy, estradiol levels remained well below the suppression level of 20 pg/mL in girls, and testosterone levels remained below the baseline level of 9.9 ng/dL in boys.

And, compared with baseline, mean predicted adult height was significantly higher through 5 years of therapy, increasing by almost 17 cm.

The researchers report that 2 girls have received a sixth implant, and levels of LH, FSH, and estradiol continue to remain below suppression thresholds.

To be eligible for the study, girls had to have Tanner breast staging of at least 2, and boys had to have testicular volume of at least 4 cc. Additionally, both girls and boys had to have a bone age that was at least 2 standard deviations above that for chronologic age.

The most common treatment-related adverse event reported by 5 participants was a mild-to-moderate reaction at the implant site, which was not of sufficient severity to prompt any withdrawals from the study.