somatropin (recombinant) (Omnitrope)
- Growth failure in children due to deficiency of growth hormone.
- Children with growth failure associated with Prader-Willi syndrome or Turner syndrome.
- Children with short stature born small for gestational age with no catch-up growth by age 2 yr.
- Children with idiopathic short stature.
- 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 and Excretion: Broken down in renal cells to amino acids that are recirculated; some liver metabolism.
Half-life: Subcut–2.5–2.8 hr.
TIME/ACTION PROFILE (growth)
|Subcut||within 3 mo||unknown||unknown|
- Hypersensitivity to growth hormone or any of the excipients
- Closure of epiphyses
- Active malignancy
- 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 severe obesity, upper airway obstruction, sleep apnea, or severe respiratory impairment (↑ risk of fatal complications).
Use Cautiously in:
- Growth hormone deficiency due to intracranial lesion
- Pituitary hormone deficiency or hypoadrenalism;
- Diabetes (may cause insulin resistance)
- Scoliosis (may cause progression)
- Turner syndrome with otitis media or cardiovascular disorders (may cause progression)
- OB: Lactation: Safety not established;
- Geri: ↑ sensitivity, ↑ risk of adverse reactions
- Pedi: Contains benzyl alcohol (may cause fatal gasping syndrome in neonates)
- Pedi: Childhood cancer survivors (↑ risk of intracranial tumors);
- Thyroid dysfunction.
Adverse Reactions/Side Effects
CNS: headache, intracranial hypertension
CV: peripheral edema
Endo: hyperglycemia, hypothyroidism, insulin resistance
Local: pain at injection site, local lipoatrophy or lipodystrophy with subcutaneous use
Misc: HYPERSENSITIVITY REACTIONS (INCLUDING ANAPHYLAXIS AND ANGIOEDEMA)
* CAPITALS indicate life-threatening.
Underline indicate most frequent.
- In patients requiring glucocorticoid/corticosteroid replacement or supplementation careful titration is required as some metabolic pathways are inhibited by somatropin.
- May alter clearance of compounds known to be metabolized by CYP450 liver enzymes including corticosteroids, steroidal hormones, anticonvulsants and cyclosporine.
- Estrogen may ↑ requirements for somatropin.
- May alter response to insulin and/or oral hypoglycemic agents, dose adjustment may be necessary.
Adult Growth Hormone Deficiency
SC (Adults) 0.04 mg/kg/wk divided into equal doses given 7 days per wk initially; may be ↑ at 4–8 wk intervals to a maximum of 0.08 mg/kg/wk.
Pediatric Growth Hormone Deficiency
SC Children 0.16–0.24 mg/kg/wk divided into equal doses given 6–7 times per wk.
Growth Failure Associated with Prader-Willi or Turner Syndrome
SC Children Prader-Willi syndrome–0.24 mg/kg/wk divided into equal doses given 6–7 times per wk; Turner syndrome–0.33 mg/kg/wk divided into equal doses given 6–7 times per wk.
Short Stature Born Small for Gestational Age
SC Children up to 0.48 mg/kg/wk divided into equal doses given 6–7 times per wk.
Idiopathic Short Stature
SC Children Up to 0.47 mg/kg/wk divided into equal doses given 6–7 times per wk.
Solution for subcutaneous injection (cartridges for use with pen device): 5 mg/1.5 mL, 10 mg/1.5 mL
Powder for subcutaneous injection: 5.8 mg/vial
- Monitor bone age annually and growth rate determinations, height, and weight every 3–6 mo during therapy.
Lab Test Considerations:
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.
- Disturbed body image (Indications)
- Rotate injection sites with each injection.
- After initial injection, use within 4 wk (3 wk for 5.8 mg vial) if stored in refrigerator.
- 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.
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