Somatropin (Recombinant)

INTRODUCTION

Indications

Treatment of HIV-associated wasting.

Action

Produce growth (skeletal and cellular). Metabolic actions include ↑ protein synthesis, ↑ 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: ↓ wasting in patients with AIDS.

Adverse Reactions/Side Effects

CV: edema of the hands and feet. Endo: hyperglycemia, hypothyroidism, insulin resistance. Local: pain at injection site, local lipoatrophy or lipodystrophy with SC use. MS: arthralgia, carpal tunnel syndrome.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Assess edema in the hands and feet using girth measurements, volume displacement, and measurement of pitting edema (See Appendix N). Report increased swelling, especially if ROM and function are compromised, or if patient exhibits signs of carpal tunnel syndrome (numbness, tingling, and weakness in median nerve distribution to the hand).

• Assess any joint pain to rule out musculoskeletal pathology; that is, try to determine if pain is drug induced rather than caused by anatomic or biomechanical problems.

• Be alert for signs of hyperglycemia and insulin resistance, including confusion, drowsiness, flushed/dry skin, fruit-like breath odor, rapid/deep breathing, polyuria, loss of appetite, and unusual thirst. Patients with diabetes mellitus should check blood glucose levels frequently.

• Monitor any decrease in metabolism that might indicate hypothyroidism. Common signs include bradycardia, lethargy, cold intolerance, weight gain, and muscle weakness. Report these signs to the physician.

• Monitor subcutaneous injection site for bruising or decreased local fat accumulation (lipoatrophy, lipodystrophy). Report prolonged or excessive injection site reactions to the physician.

Interventions

• Design and implement therapeutic exercise programs to capitalize on growth hormone effects and increase muscle strength and decrease muscle wasting in patients with AIDs.

• Do not apply physical agents (heat, cold, electrotherapeutic modalities) or massage over the injection site; these interventions can alter drug absorption from subcutaneous tissues.

Patient/Client-Related Instruction

• Advise patient and family/caregivers to adhere to recommended dosing schedule. Emphasize that growth hormones must not be used to increase athletic performance, and that administration to people 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).

Pharmacokinetics

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: SC—4.28 ± 2.15 hr.