Growth hormone deficiency [GHD]

The posology and administration should be individualised for each patient.

Starting dose

The recommended starting dose of lonapegsomatropin is 0.24 mg somatropin/kg body weight, given once weekly. The recommended starting dose strengths for such a dose by weight range can be found in Table 1.

Table 1. Recommended dose for patients by weight, when prescribed doses of 0.24 mg somatropin/kg/week:

If prescribing a dose other than 0.24 mg somatropin/kg/week, calculate the total weekly dose (in mg somatropin) and select the appropriate dose strength as follows:

• Total weekly dose (mg somatropin) = prescribed dose (mg somatropin/kg) x patient’s body weight (kg)
• Round the total weekly dose (mg somatropin) to the closest dose strength while also considering treatment goals and clinical response.

Starting dose for patients switching from daily somatropin medicinal products

If changing therapy to once-weekly lonapegsomatropin from daily somatropin, there should be at least 8 hours between the final dose of once-daily somatropin and the first dose of lonapegsomatropin.

In children switching from daily somatropin, physicians may adjust the starting dose taking into consideration the current somatropin dose, individual clinical response, and clinical considerations specific to the patient.

For children switching from daily somatropin medicinal products at a weekly dose equal to or greater than 0.24 mg somatropin/kg body weight, the recommended starting dose of lonapegsomatropin is 0.24 mg somatropin/kg body weight (see Table 1).

For children switching from daily somatropin medicinal products at a weekly dose less than 0.24 mg somatropin/kg body weight, use the previously prescribed weekly dose as the recommended starting dose of lonapegsomatropin (see equation above).

Dose titration

The dose of lonapegsomatropin should be individually adjusted for each patient based on clinical response, adverse reactions, and/or serum insulin-like growth factor-1 (IGF-1) concentrations outside the targeted range. Available somatropin dose strengths can be found in section 1.

Average IGF-1 standard deviation score (SDS) levels (drawn 4-5 days after dosing) can be used as guidance for dose titration (see Table 2). It is necessary to wait a minimum of 2 weeks after initiation of lonapegsomatropin or after any dose change before assessing the resulting IGF-1 SDS levels. Dose adjustments should be targeted to achieve average IGF-1 SDS levels in the normal range, i.e. between -2 and +2 (preferably close to 0 SDS).

IGF-1 SDS levels may vary over time, and therefore routine monitoring of serum IGF-1 SDS levels throughout the course of treatment is recommended, especially during puberty.

Table 2. Recommended change in somatropin dose strength for average IGF-1 SDS categories:

Treatment evaluation

Evaluation of efficacy and safety should be considered at approximately 6- to 12-month intervals and may be assessed by evaluating auxological parameters, biochemistry (IGF-1, hormones, glucose, and lipid levels), and pubertal status. More frequent evaluations should be considered during puberty.

Treatment should be discontinued in patients with annualised height velocity <2 cm/year, final height achievement, height velocity SDS < +1 after the first year of treatment, or in case bone age is >14 years (girls) or >16 years (boys) which corresponds to the closure of the epiphyseal growth plates.

Once the epiphyses are fused, patients should be clinically re-evaluated for the need for growth hormone treatment.

Oral oestrogen therapy

Females on oral oestrogen-containing therapy may require a higher dose of growth hormone to achieve the treatment goal.

Missed dose

If a dose is missed, it should be administered as soon as possible and no more than 2 days after the missed dose. If more than 2 days have passed, the missed dose should be skipped, and the next dose should be administered on the regularly scheduled day. In each case, patients can then resume their regular once weekly dosing schedule.

Changing the dosing day

The day of weekly injection can be changed to a different day of the week. Lonapegsomatropin can be administered 2 days before or 2 days after the scheduled dosing day. It should be ensured that at least 5 days will pass between the last dose and the newly-established regular once weekly dosing day.

Each injection should be administered subcutaneously once-weekly in the abdomen, buttock or thigh. The site of administration should be varied to prevent lipoatrophy.