What other growth hormone therapies besides Genotropin (somatropin), Norditropin (somatropin), and Omnitrope (somatropin) can be used for Prader-Willi syndrome?

Growth Hormone Therapies for Prader-Willi Syndrome

FDA-approved growth hormone therapies for Prader-Willi syndrome beyond Genotropin, Norditropin, and Omnitrope include Humatrope, Nutropin, Saizen, and Zomacton, which are all somatropin products with the same active ingredient but different manufacturers.

Available Growth Hormone Products for PWS

Growth hormone therapy is considered the first-line treatment for children with Prader-Willi syndrome (PWS), as it significantly improves body composition, motor development, and growth 1, 2. The following somatropin products are available for treating PWS:

1. Already mentioned in question:

   • Genotropin (somatropin)
   • Norditropin (somatropin)
   • Omnitrope (somatropin)

2. Additional FDA-approved options:

   • Humatrope (somatropin) - Eli Lilly
   • Nutropin/Nutropin AQ (somatropin) - Genentech
   • Saizen (somatropin) - EMD Serono
   • Zomacton (somatropin) - Ferring Pharmaceuticals

Clinical Benefits of Growth Hormone Therapy in PWS

Growth hormone therapy in PWS patients provides multiple benefits that improve quality of life and reduce morbidity:

• Increases height (1.67 SDS improvement) 3
• Improves body composition with decreased fat mass (-6.5%) 3
• Enhances lean body mass (2.2 kg increase in adults) 4, 5
• Improves motor development and physical strength 6
• Normalizes body habitus 1
• May improve cognitive function 2, 3

Initiation and Monitoring Protocol

When initiating any growth hormone therapy for PWS:

1. Pre-treatment evaluation:

   • Polysomnography (sleep study) before starting treatment 1, 2
   • Early morning serum ACTH and cortisol evaluation 1
   • Baseline IGF-1 levels 1

2. Follow-up monitoring:

   • Repeat polysomnography 6-10 weeks after starting therapy 1, 2
   • Monitor IGF-1 levels at least twice yearly 1, 2
   • Monitor head circumference at each visit 1, 2
   • Annual evaluation for sleep disorders 1

Safety Considerations and Risks

Important safety considerations when using any growth hormone product:

• Respiratory concerns: Increased risk of sleep apnea; deaths have occurred in children with PWS within 6 months of starting therapy 1, 7
• Scoliosis: Most commonly reported adverse event (monitor regularly) 7
• Metabolic effects: Monitor for hyperglycemia and potential development of type 2 diabetes 7
• Water retention: Can occur as a side effect 4, 5

Contraindications

Growth hormone therapy should not be started in patients with:

• Closed epiphyses 1
• Known hypersensitivity to the active substance 1
• Severe secondary hyperparathyroidism 1
• Proliferative or severe non-proliferative diabetic retinopathy 1
• Active malignancy 1
• Acute critical illness 1

Practical Considerations

• Growth hormone insufficiency is considered universal in PWS, so provocative diagnostic testing is not required 1
• Treatment can begin as early as 2-3 months of age, though FDA approval is for children older than 2 years with documented growth failure 1, 2
• Doses should be individualized to keep IGF-1 levels in the physiologic range 1
• All growth hormone products contain the same active ingredient (somatropin) but may differ in delivery devices, preservatives, and reconstitution requirements

Key Pitfalls to Avoid

• Failure to monitor for sleep apnea: Always conduct polysomnography before and after initiating therapy
• Overlooking adrenal insufficiency: Consider prophylactic hydrocortisone during critical illness
• Inadequate monitoring: Regular follow-up for IGF-1 levels, sleep disorders, and scoliosis is essential
• Starting treatment without proper screening: Comprehensive evaluation for contraindications is necessary

Growth hormone therapy should be managed in consultation with a pediatric endocrinologist who has experience treating PWS patients 1, 2.