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Zomacton Generic Name & Formulations
Legal Class
Rx
General Description
Somatropin (rDNA origin) 5mg, 10mg; lyophilized pwd for SC inj after reconstitution; contains mannitol; diluents contain benzyl alcohol or metacresol.
Pharmacological Class
Growth hormone (GH).
How Supplied
Vials—1 (w. diluent)
Manufacturer
Mechanism of Action
Somatropin binds to dimeric GH receptors located within the cell membranes of target tissue cells. This interaction results in intracellular signal transduction and subsequent induction of transcription and translation of GH-dependent proteins including IGF-1, IGF BP-3 and acid-labile subunit. Somatropin has direct tissue and metabolic effects or effects mediated indirectly by IGF-1, including stimulation of chondrocyte differentiation, and proliferation, stimulation of hepatic glucose output, protein synthesis, and lipolysis.
Zomacton Indications
Indications
Growth failure in children due to inadequate endogenous GH secretion. Children with short stature associated with Turner syndrome. Children with idiopathic short stature (ISS). Children with short stature homeobox-containing gene (SHOX) deficiency. Children with short stature born small for gestational age (SGA) with no catch-up growth by age 2–4yrs. Replacement of endogenous GH in adults with GH deficiency.
Zomacton Dosage and Administration
Adult
Give by SC inj to the back of upper arm, abdomen, buttock, or thigh. Rotate inj sites. Non-weight based: initially ~0.2mg/day (range: 0.15–0.3mg/day); increase dose in increments of ~0.1–0.2mg/day every 1–2mos based on response and serum IGF-1 levels. Weight-based: initially 0.006mg/kg/day; increase dose based on individual requirements to max 0.0125mg/kg/day. Obese: weight-based dosing not recommended.
Children
Give by SC inj to the back of upper arm, abdomen, buttock, or thigh. Rotate inj sites. Individualize. Divide weekly dosage into equal doses over 3, 6 or 7 days. GH deficient: 0.18–0.3mg/kg/week (0.026–0.043mg/kg/day). Turner syndrome: up to 0.375mg/kg/week (up to 0.054mg/kg/day). ISS: up to 0.37mg/kg/week (up to 0.053 mg/kg/day). SHOX deficiency: 0.35mg/kg/week (0.05mg/kg/day). SGA: up to 0.47mg/kg/week (up to 0.067mg/kg/day). Discontinue once epiphyseal fusion has occurred.
Zomacton Contraindications
Contraindications
Acute critical illness due to open heart surgery, abdominal surgery, multiple accidental trauma or those with acute respiratory failure. Children with closed epiphysis. Active malignancy. Diabetic retinopathy. History of upper airway obstruction or sleep apnea, severe obesity, or severe respiratory impairment in Prader-Willi syndrome (PWS) patients.
Zomacton Boxed Warnings
Not Applicable
Zomacton Warnings/Precautions
Warnings/Precautions
Increased mortality in those with acute critical illness (see Contraindications); weigh potential treatment benefit vs the potential risk. PWS: evaluate baseline respiratory function; monitor weight and for respiratory infection; interrupt if signs of upper airway obstruction and/or sleep apnea occurs. History of GHD secondary to intracranial neoplasm: monitor routinely for tumor progression or recurrence. Increased risk of developing malignancies. Monitor for increased growth or malignant changes of preexisting nevi. Diabetes. Obesity. Hypothyroidism. Scoliosis. Turner syndrome. Monitor thyroid function, glucose tolerance, and for intracranial hypertension (do baseline and periodic funduscopic exams). Hypoadrenalism: monitor for reduced serum cortisol levels. Elderly (consider lower starting dose). Neonates: reconstitute with normal saline for inj instead. Pregnancy, nursing mothers: reconstitute with normal saline or use benzyl alcohol-free formulation.
Zomacton Pharmacokinetics
Absorption
Time to peak plasma concentration: ~4.5 hours. Absolute bioavailability: ~70%.
Distribution
Volume of distribution: 53.3 L (after a 4mg SC dose).
Elimination
Renal. Half-life: 2.3 hours.
Zomacton Interactions
Interactions
May require increase in maintenance or stress doses of glucocorticoids in hypoadrenalism. May be antagonized by glucocorticoids; adjust dose. Concomitant oral estrogen: may need higher somatropin dose. May affect CYP450 substrates; monitor. Concomitant thyroid replacement therapy, antidiabetic medications: may need to adjust doses of these.
Zomacton Adverse Reactions
Adverse Reactions
Upper RTI, fever, pharyngitis, headache, otitis media, edema, arthralgia, paresthesia, myalgia, carpal tunnel syndrome, peripheral edema, flu syndrome, hypothyroidism, hyperglycemia, impaired glucose tolerance; fluid retention, severe hypersensitivity reactions, pancreatitis, lipoatrophy, elevated serum phosphorous, alkaline phosphatase, parathyroid hormone and IGF-1; also in children: slipped capital femoral epiphysis (monitor).
Zomacton Clinical Trials
See Literature
Zomacton Note
Not Applicable
Zomacton Patient Counseling
See Literature
