somatropin, recombinant

Action

Stimulates linear and skeletal growth, increases number and size of muscle cells, and influences internal organ size

Availability

Genotropin injection: 1.5 mg (about 4 international units/vial), 5.8 mg (about 15 international units/vial), 13.8 mg (about 41.4 international units/vial)

Humatrope injection: 2 mg (about 6 international units/vial), 5 mg (about 15 international units/vial), 6 mg (about 18 international units/vial), 12 mg (about 36 international units/vial), 24 mg (about 72 international units/vial)

Norditropin injection: 4 mg (12 international units/vial), 8 mg (24 international units/vial)

Norditropin injection cartridge: 5 mg/1.5 ml, 10 mg/1.5 ml, 15 mg/1.5 ml

Nutropin AQ injection: 10 mg

Nutropin AQ Pen injection cartridge: 10 mg

Nutropin Depot: 13.5-mg, 18-mg, and 22.5-mg single-use vials; 13.5-mg, 18-mg, and 22.5-mg kits

Nutropin injection: 5 mg (about 15 international units/vial), 10 mg (about 30 international units/vial)

Saizem injection: 5 g (about 15 international units/vial)

Serostim injection: 5 mg (about 15 international units/vial), 6 mg (about 18 international units/vial)

Tev-Tropin injection: 5 mg

Zorbtive injection: 8.8 mg in 10-ml vial

Indications and dosages

➣ Growth failure in children with inadequate endogenous GH

Children: 0.16 to 0.24 mg/kg (Genotropin) subcutaneously q week in six or seven divided doses. Or 0.18 mg/kg/week (Humatrope) subcutaneously or I.M., divided equally and given on three alternate days six times weekly (or daily, if epiphyseal closure hasn't occurred). Or 0.024 to 0.034 mg/kg (Norditropin) subcutaneously six or seven times each week using NordiPen injection pen. Or 0.3 mg/kg/week (Nutropin AQ, Nutropin AQ Pen, Tev-Tropin) subcutaneously in equally divided daily doses. Or 0.06 mg/kg (Saizen) subcutaneously or I.M. three times weekly.

➣ Endogenous GH replacement in adults with GH deficiency

Adults: 0.04 mg/kg/week (Genotropin) subcutaneously in six or seven divided doses. Or 0.006 mg/kg/day (Humatrope) subcutaneously. Or initially, no more than 0.006 mg/kg/day (Nutropin AQ, Nutropin AQ Pen, Tev-Tropin) subcutaneously; may increase to a maximum of 0.025 mg/kg daily in patients younger than age 35 or 0.0125 mg/kg/day in patients ages 35 and older. Or 0.005 mg/kg/day (Saizen) subcutaneously; may increase to a maximum of 0.01 mg/kg/day after 4 weeks, depending on patient tolerance.

➣ Short stature related to Turner's syndrome

Children: 0.375 mg/kg/week (Humatrope) subcutaneously, divided into equal doses given on 3 alternate days or daily. Or up to 0.375 mg/kg/week (Nutropin AQ, Nutropin AQ Pen) subcutaneously, divided into equal doses given three or seven times weekly.

➣ Idiopathic short stature (non-GH-deficient) in children whose epiphyses haven't closed

Children: Up to 0.37 mg/kg (Humatrope) subcutaneously q week. Divide dosage and give in equal doses six or seven times weekly.

➣ Growth failure in children with Prader-Willi syndrome

Children: 0.24 mg/kg/week (Genotropin) subcutaneously in six or seven divided doses

➣ Infants born small for gestational age

Children: 0.48 mg/kg/week (Genotropin) subcutaneously in six or seven divided doses

➣AIDS wasting or cachexia

Adults and children weighing more than 55 kg (121 lb): 6 mg (Serostim) subcutaneously at bedtime

Adults and children weighing 45 to 55 kg (99 to 121 lb): 5 mg (Serostim) subcutaneously at bedtime

Adults and children weighing 35 to 45 kg (77 to 99 lb): 4 mg (Serostim) subcutaneously at bedtime

Adults and children weighing less than 35 kg (77 lb): 0.1 mg/kg/day (Serostim) subcutaneously at bedtime

➣ Growth failure due to chronic renal insufficiency (up to time of kidney transplantation)

Children: Up to 0.35 mg/kg/weekly (Nutropin AQ, Nutropin AQ Pen) subcutaneously, divided into daily doses

➣ Short bowel syndrome in patients receiving specialized nutritional support

Adults: 0.1 mg/kg/day subcutaneously (Zorbtive), to a maximum of 8 mg/day for no more than 4 weeks

Contraindications

• Hypersensitivity to drug, benzyl alcohol, glycerin, or metacresol (with some diluents)

• Active neoplasia

• Acute, critical illness after open-heart surgery, acute respiratory failure, or multiple trauma

• Children with closed epiphyses

• Neonates (Zorbtive)

Precautions

Use cautiously in:

• hypothyroidism

• diabetes mellitus.

Administration

• Reconstitute by injecting supplied diluent through rubber top of vial and aiming liquid stream at side of vial. Swirl vial gently to mix; don't shake.

• Inspect reconstituted solution. Don't use if it has visible particles or is cloudy.

• Keep diluted drug refrigerated; use within 14 days.

• When using prefilled cartridges, follow manufacturer's instructions carefully.

• Know that patients receiving Zorbtive for short bowel syndrome may receive specialized nutritional support as needed.

Adverse reactions

CNS: headache, weakness

CV: mild and transient edema

GU: hypercalciuria

Hematologic: leukemia

Metabolic: fluid retention, mild hyperglycemia, hypothyroidism, ketosis

Musculoskeletal: localized muscle pain, tissue swelling, joint pain

Skin: rash, urticaria

Other: pain, inflammation at injection site

Interactions

Drug-drug. Androgens, thyroid hormone: epiphyseal closure

Corticotrophin, corticosteroids: inhibited growth response (with long-term use)

Drug-diagnostic tests. Alkaline phosphatase, glucose, inorganic phosphorus, parathyroid hormone: increased levels

Patient monitoring

• Monitor patient's height, X-rays, blood chemistry results, blood glucose level, and thyroid function studies.

See Watch for signs and symptoms of leukemia.

Patient teaching

• Advise patient and parents that regular check-ups and blood tests are needed to detect adverse reactions.

• Teach parents how to reconstitute and administer drug. Stress importance of following manufacturer's instructions carefully when using prefilled cartridges.

• Teach parents about proper handling and disposal of syringes, needles, and cartridges.

• As appropriate, review all significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.