somatropin (Recombinant): soe-ma-TROE-pin

Therapeutic Classification: hormones

Pharmacologic Classification: growth hormones

• Growth failure in children due to deficiency of growth hormone.
• Children with short stature associated with Noonan syndrome or Turner syndrome.
• Children with short stature born small for gestational age with no catch-up growth by age 2–4 yr.
• Growth hormone deficiency in adults as a result of pituitary disease, hypothalamic disease, surgery, radiation, trauma, or childhood onset.

• Produce growth (skeletal and cellular).
• Metabolic actions include:
  • Increased protein synthesis,
  • Increased carbohydrate metabolism,
  • Lipid mobilization,
  • Retention of sodium, phosphorus, and potassium.
• Somatropin has the same amino acid sequence as naturally occurring growth hormone and is produced by recombinant DNA techniques.
• Growth hormone enhances GI tract mucosal transport of water, electrolytes and nutrients.

• Increased skeletal growth in children with growth hormone deficiency.
• Replacement of somatropin in deficient adults.

Absorption: Well absorbed.

Distribution: Localize to highly perfused organs (liver, kidneys).

Metabolism/Excretion: Broken down in renal cells to amino acids that are recirculated; some liver metabolism.

Half-life: Subcut — 3.8 hr.

(growth)

Contraindicated in:

• Hypersensitivity to growth hormone or phenol preservative
• Closure of epiphyses
• Active neoplasia
• Acute critical illness secondary to complications of open heart surgery, abdominal surgery or trauma or those with acute respiratory failure
• Diabetic retinopathy
• Prader-Willi syndrome with obesity and respiratory impairment (↑ risk of fatal complications; can be used only if growth hormone deficiency is documented).

Use Cautiously in:

• Growth hormone deficiency due to intracranial lesion
• Pituitary hormone deficiency or hypoadrenalism
• Diabetes (may cause insulin resistance)
• Thyroid dysfunction
• OB: Lactation: Safety not established
• Geri: ↑sensitivity, ↑ risk of adverse reactions
• Pedi: Childhood cancer survivors (↑ risk of intracranial tumors).

CV: edema of the hands and feet.

Endo: hyperglycemia, hypothyroidism, insulin resistance.

GI: PANCREATITIS.

Local: pain at injection site, local lipoatrophy or lipodystrophy with subcutaneous use.

MS: arthralgia.

Misc: HYPERSENSITIVITY REACTIONS (INCLUDING ANAPHYLAXIS AND ANGIOEDEMA).

Drug-Drug:

• Excessive corticosteroid use (equivalent to 10–15 mg/m²/day) may ↓ response to growth hormone.

Adult Growth Hormone Deficiency

• SC (Adults): 0.004 mg/kg/day, may be ↑ to 0.016 mg/kg/day after 6 wk or 0.2 mg/day starting dose (without consideration of body weight), then gradually ↑ by 0.1–0.2 mg/day q 1–2 mo until clinical response achieved.

Pediatric Growth Hormone Deficiency

• SC (Children): 0.024–0.034 mg/kg/day given 6–7 times weekly.

Short Stature Associated with Noonan or Turner Syndrome

• SC (Children): Noonan syndrome–Up to 0.066 mg/kg/day may be used; Turner syndrome–Up to 0.067 mg/kg/day may be used.

Short Stature Born Small for Gestational Age

• SC (Children): Up to 0.067 mg/kg/day may be used.

• Solution for subcutaneous injection (FlexPro prefilled pens): 5 mg/1.5 mL (orange); 10 mg/1.5 mL (blue); 15 mg/1.5 mL (green); 30 mg/3 mL (purple);

• Growth Failure: Monitor bone age annually and growth rate determinations, height, and weight every 3–6 mo during therapy.

• Monitor thyroid function prior to and during therapy. May decrease T⁴, radioactive iodine uptake, and thyroxine-binding capacity. Hypothyroidism necessitates concurrent thyroid replacement for growth hormone to be effective. Serum inorganic phosphorus, alkaline phosphatase, and parathyroid hormone may ↑ with somatropin therapy.
  • Monitor blood glucose periodically during therapy. Diabetic patients may require ↑ insulin dose.
  • Monitor for development of neutralizing antibodies if growth rate does not exceed 2.5 cm/6 mo.
  • Monitor alkaline phosphatase closely in patients with adult growth hormone deficiency.

• Rotate injection sites with each injection.
  • Norditropin FlexPro prefilled pens contain multiple doses. After initial injection, use within 4 wk if stored in refrigerator or within 3 wk if stored at room temperature.

• Instruct patient and parents on correct procedure for reconstituting medication, site selection, technique for subcut injection, and disposal of needles and syringes. Review dose schedule. Parents should report persistent pain or edema at injection site.
• Explain rationale for prohibition of use for increasing athletic performance. Administration to persons without growth hormone deficiency or after epiphyseal closure may result in acromegaly (coarsening of facial features; enlarged hands, feet, and internal organs; increased blood glucose; hypertension).
• Assure parents and child that these dose forms are synthetic and therefore not capable of transmitting Creutzfeldt-Jakob disease, as was the original somatropin, which was extracted from human cadavers.
• Advise parents to monitor blood glucose closely in children with diabetes mellitus. Parents should also be advised to report persistent severe abdominal pain; may be a symptom of pancreatitis, and signs and symptoms of hypersensitivity reactions (rash, facial swelling, difficulty breathing) immediately to health care professional..
• Emphasize need for regular follow-up with endocrinologist to ensure appropriate growth rate, to evaluate lab work, and to determine bone age by x-ray exam.

• Child’s attainment of adult height in growth failure secondary to pituitary growth hormone deficiency. Therapy is limited to period before closure of epiphyseal plates (approximately up to 14–15 yr in girls, 15–16 yr in boys).
• Replacement of growth hormone in deficient adults.

Norditropin FlexPro

Norditropin Nordiflex

• Disturbed body image (Indications).