somatropin (recombinant)

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.

Therapeutic effects:

Enhanced GI absorption of water, electrolytes and nutrients in short bowel syndrome.

Pharmacokinetics ⬆ ⬇

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: 4.3 hr.

Time/Action Profile ⬆ ⬇

ROUTE	ONSET	PEAK	DURATION
SUBQ	unknown	unknown	unknown

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Closure of epiphyses;
Active neoplasia;
Hypersensitivity to growth hormone or benzyl alcohol;
Acute critical illness (therapy should not be initiated) or 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);
OB: Pregnancy.

Use Cautiously in:

Growth hormone deficiency due to intracranial lesion;
Coexisting adrenocorticotropic hormone (ACTH) deficiency;
Diabetes (may cause insulin resistance);
Thyroid dysfunction;
Lactation: Safety not established in breastfeeding;
Geri: Appears on Beers list. risk of edema, arthralgia, carpal tunnel syndrome, gynecomastia, and impaired fasting glucose in older adults. Avoid use in older adults, except for confirmed growth hormone deficiency due to an established etiology.

Adv. Reactions/Side Effects ⬆ ⬇

CV: edema of hands and feet

Endo: hyperglycemia, hypothyroidism, insulin resistance

GI: flatulence, vomiting

Local: pain at injection site, local lipoatrophy or lipodystrophy

MS: arthralgia, musculoskeletal pain

Neuro: malaise, dizziness

Misc: fever

Interactions ⬆ ⬇

Drug-drug:

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

Route/Dosage ⬆ ⬇

SC (Adults ): 0.1 mg/kg/day for 4 wk (not to exceed 8 mg/dose), dose may be stopped for 5 days and resumed at half dose for fluid retention or arthalgias.

Availability ⬆ ⬇

Powder for injection: 8.8 mg/vial

Assessment ⬆ ⬇

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. Patients with diabetes may require ↑ insulin dose.

Implementation ⬆ ⬇

Rotate injection sites with each injection.
- Reconstitute each 8.8 mg vial with 1 or 2 mL bacteriostatic water for injection. Solution should be clear upon reconstitution. Do not administer if cloudy upon reconstitution or after refrigeration. After refrigeration may contain small particles, which should disappear when allowed to warm to room temperature. Solution reconstituted with bacteriostatic water is stable for 14 days if refrigerated.
SC: Injection volume should not exceed 1 mL.

Patient/Family Teaching ⬆ ⬇

Instruct patient and parents on correct procedure for reconstituting medication, site selection, technique for SUBQ injection, and disposal of needles and syringes. Review dosage schedule. Patients 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 patient 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.
Rep: Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇