Endocrine Abstracts

Background: Gonadotrophin-Releasing Hormone agonists (GnRHa) are the mainstay of treatment for central precocious puberty (CPP). The long-acting formulation, Decapeptyl SR (Triptorelin pamoate), is commonly used, given as an 11.25 mg intramuscular injection 12-weekly. Recently, a 24-weekly, 22.5 mg preparation, has been introduced with reduced numbers of injections offering cost and patient benefits. Results of a two-centre UK study demonstrated no significant difference in efficacy between the 12 and 24-weekly preparations, with 24-weekly universally preferred by patients. Concerns about off-licence dosing (reduced dosing intervals) and a perceived lack of efficacy of the 22.5 mg preparation in our centre led to this service evaluation.

Methods: A retrospective casenotes review of patients treated with GnRHa between October 2014-October 2023. Data were collected on: patient demographics; clinical, biochemical and radiological parameters; and GnRHa doses with reasons for dose changes and side effects.

Results: 147 patients were prescribed GnRHa, with 48 excluded for incomplete data. Of the remaining 99 (89F and 10M, mean age at presentation 6.7yrs +/-1.68 and 5.8 years +/- 2.20 years respectively), 74 had received only 11.25 mg, 10 only 22.5 mg and 15 both preparations. The 22.5 mg preparation was introduced in 2020. No patients in 2022 or 2023 were started on 22.5 mg. Of patients on 11.25 mg, 90% were started on dosing intervals <12-weekly (67% on 10-weekly, 22% on 8-weekly) and for those on 22.5 mg 58% on <24-weekly (17% on 22-weekly and 42% on 20-weekly). Approximately 50% (same proportion for the two preparations) had their dosing intervals reduced during treatment; common reasons cited were mood swings (25%), continued breast development (24%) and lack of suppression of sex hormones (12%). Side effects were recorded in 22/74 (30%) of patients on 11.25 mg and 6/10 (60%) on 22.5 mg; mood swings and weight gain being the most common.

Discussion: Our centre frequently reduces decapeptyl dosing intervals and very few children are on the more patient-friendly 22.5 mg preparation. This is not the experience reported by two large tertiary UK centres who have collected similar data. There is a need for a review of current variations in GnRHa use, with the introduction of more stringent, evidence-based criteria for GnRHa starting doses and dose changes.