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Humatrope (somatropin) injection, for subcutaneous use

Summary about Humatrope

Growth hormone (GH) or somatotropin is a peptide produced by the somatotroph cells in the anterior pituitary gland. It binds to a transmembrane receptor and leads to the production of insulin-like growth factor I (IGF-I), IGF binding protein 3 (IGFBP-3), and the acid-labile subunit (ALS). This 3-peptide compound is brought to target cells, binds to IGF-I receptor, and stimulates metabolic functions. In infancy, childhood and adolescence GH is essential for normal linear growth.

Humatrope (somatropin) injections for subcutaneous use is a man-made form of human growth hormone. It was first approved in 1987 to treat children who are growing slowly because they do not make enough growth hormone on their own.

 

Figure 1: Humatrope pens (Source: https://www.humatrope.com)

 

 

Humatrope is used to treat children who are short or growing slowly because of they:

  • Do not make enough growth hormone on their own
  • Have Turner Syndrome
  • Have idiopathic short stature, which means they are shorter than 98.8% of other children of the same age and sex, are growing at a rate not likely to allow them to reach normal adult height, and for whom no other cause of short stature can be found
  • Have SHOX deficiency
  • Were born smaller than normal for the number of weeks of pregnancy and do not catch up in height by 2 to 4 years of age

Humatrope is also used to treat adults who have growth hormone deficiency that began either in:

  • Adulthood (as a result of pituitary disease, hypothalamic disease, surgery, radiation therapy, or trauma); or
  • Childhood. Patients treated for growth hormone deficiency in childhood whose bones have stopped growing should be reevaluated to determine if they should continue growth hormone

The goal of GH therapy in pediatric patients is to sustain normal linear growth and achieve a normal adult height. In addition to promoting linear growth, GH has favourable effects on muscle accretion and bone mineral density. GH stimulates osteoblast and osteoclast differentiation and promotes the accretion of bone mass. GH stimulates the proliferation of adipose precursor cells, restricts their differentiation into mature adipocytes, and limits deposition of fat in the abdominal visceral area. Consequently, children with growth hormone deficiency (GHD) demonstrate reduced linear growth, reduced lean body mass, increased body fat with disproportionate deposition of visceral and truncal fat, subnormal bone mineral density and lipid abnormalities. Untreated patients with adult onset GHD demonstrate all the pediatric consequences with the exception of a linear growth effect. Untreated adults with GHD have also decreased muscle strength, impaired cardiac function, and decreased quality of life.

Humatrope is contrainidicated in following cases:

  • Acute critical illness
  • Children with Prader-Willi Syndrome who are severely obese or have severe respiratory impairment – reports of sudden death
  • Active malignancy
  • Hypersensitivity to somatropin or its excipients
  • Active proliferative or severe non-proliferative diabetic retinopathy
  • Children with closed epiphyses
  • Known hypersensitivity to somatropin or excipients.

 

Humatrope (somatropin)

Active Ingredient

Somatropin

Administration Route

Subcutaneous

Alcohol Warning

No data about interaction

Available Strength

Humatrope is a sterile, white lyophilized powder available in the following vial and cartridge sizes:
  • 5 mg vial and a 5-mL vial of diluent for Humatrope
  • 6 mg cartridge (gold) and a prefilled syringe of diluent for Humatrope
  • 12 mg cartridge (teal) and a prefilled syringe of diluent for Humatrope
  • 24 mg cartridge (purple) and a prefilled syringe of diluent for Humatrope

Humatrope cartridges should be used only with the appropriate corresponding pen device.

Breastfeeding Warning

Caution is recommended. Excretion into human milk is unknown.

Following subcutaneous administration of radiolabelled medication in animal studies, radioactivity was transferred to milk reaching four  times the concentration found in maternal plasma. However, absorption of the intact protein in the gastrointestinal tract of the infant is considered extremely unlikely.

Clinical Pharmacology

Pharmacodynamics

Tissue Growth:
The primary and most intensively studied action of somatropin is the stimulation of linear growth. This effect is demonstrated in children with GHD.

Skeletal Growth:
The measurable increase in bone length after administration of somatropin results from its effect on the cartilaginous growth areas of long bones. Studies in vitro have shown that the incorporation of sulfate into proteoglycans is not due to a direct effect of somatropin, but rather is mediated by the somatomedins or insulin-like growth factors (IGFs). The somatomedins, among them IGF-I, are polypeptide hormones which are synthesized in the liver, kidney, and various other tissues. IGF-I levels are low in the serum of hypopituitary dwarfs and hypophysectomized humans or animals, and increase after treatment with somatropin.

Cell Growth:
It has been shown that the total number of skeletal muscle cells is markedly decreased in children with short stature lacking endogenous GH compared with normal children, and that treatment with somatropin results in an increase in both the number and size of muscle cells.

Organ Growth:
Somatropin influences the size of internal organs, and it also increases red cell mass.

Protein Metabolism:
Linear growth is facilitated in part by increased cellular protein synthesis. This synthesis and growth are reflected by nitrogen retention which can be quantitated by observing the decline in urinary nitrogen excretion and blood urea nitrogen following the initiation of somatropin therapy.

Carbohydrate Metabolism:
Hypopituitary children sometimes experience fasting hypoglycemia that may be improved by treatment with somatropin. In healthy subjects, large doses of somatropin may impair glucose tolerance. Although the precise mechanism of the diabetogenic effect of somatropin is not known, it is attributed to blocking the action of insulin rather than blocking insulin secretion. Insulin levels in serum actually increase as somatropin levels increase. Administration of human growth hormone to normal adults and patients with growth hormone deficiency results in increases in mean serum fasting and postprandial insulin levels, although mean values remain in the normal range. In addition, mean fasting and postprandial glucose and hemoglobin A1c levels remain in the normal range.

Lipid Metabolism:
Somatropin stimulates intracellular lipolysis, and administration of somatropin leads to an increase in plasma free fatty acids and triglycerides. Untreated GHD is associated with increased body fat stores, including increased abdominal visceral and subcutaneous adipose tissue. Treatment of growth hormone deficient patients with somatropin results in a general reduction of fat stores, and decreased serum levels of low density lipoprotein (LDL) cholesterol.

Mineral Metabolism:
Administration of somatropin results in an increase in total body potassium and phosphorus and to a lesser extent sodium. This retention is thought to be the result of cell growth. Serum levels of phosphate increase in children with GHD after somatropin therapy due to metabolic activity associated with bone growth. Serum calcium levels are not altered. Although calcium excretion in the urine is increased, there is a simultaneous increase in calcium absorption from the intestine. Negative calcium balance, however, may occasionally occur during somatropin treatment.

Connective Tissue Metabolism:
Somatropin stimulates the synthesis of chondroitin sulfate and collagen, and increases the urinary excretion of hydroxyproline.

Pharmacokinetics

Absorption

Humatrope has been studied following intramuscular, subcutaneous, and intravenous administration in adult volunteers. The absolute bioavailability of somatropin is 75% and 63% after subcutaneous and intramuscular administration, respectively.

Distribution

The volume of distribution of somatropin after intravenous injection is about 0.07 L/kg.

Metabolism

Extensive metabolism studies have not been conducted. The metabolic fate of somatropin involves classical protein catabolism in both the liver and kidneys. In renal cells, at least a portion of the breakdown products of somatropin is returned to the systemic circulation. In healthy volunteers, mean somatropin clearance is 0.14 L/hr/kg. The mean half-life of intravenous somatropin is 0.36 hours, whereas subcutaneously and intramuscularly administered somatropin have mean half-lives of 3.8 and 4.9 hours, respectively. The longer half-life observed after subcutaneous or intramuscular administration is due to slow absorption from the injection site.

Excretion

Urinary excretion of intact Humatrope has not been measured. Small amounts of somatropin have been detected in the urine of pediatric patients following replacement therapy.

Specific Populations:

Geriatric patients: The pharmacokinetics of Humatrope have not been studied in patients greater than 65 years of age.

Pediatric patients: The pharmacokinetics of Humatrope in pediatric patients are similar to those of adults.

Gender: No gender-specific pharmacokinetic studies have been performed with Humatrope. The available literature indicates that the pharmacokinetics of somatropin are similar in men and women.

Race: No data are available.

Renal, hepatic insufficiency: No studies have been performed with Humatrope.

 

Cost

 

Approximate Retail Price

from  http://www.goodrx.com/Humatrope

lyophilisate for solution for injection:

  • 24 mg (2 cartridge, 24 mg): $10,401.00

lyophilisate for solution for injection:

  • 5 mg (1 vials, 5 mg): $671.99

lyophilisate for solution for injection:

  • 6 mg (1 cartridge, 6 mg): $883.44

lyophilisate for solution for injection:

  • 12 mg (1 cartridge, 12 mg): $4,417.20

Dosage Form

Injection for subcutaneous use

Dose Schedule

Pediatric GH deficiency: 0.18 to 0.30 mg/kg/week

Turner syndrome: Up to 0.375 mg/kg/week

Idiopathic short stature: Up to 0.37 mg/kg/week

SHOX deficiency: 0.35 mg/kg/week

Small for gestational age: Up to 0.47 mg/kg/week

Adult GH deficiency: Either a non-weight based or a weight-based dosing regimen may be followed, with doses adjusted based on treatment response and IGF-I concentrations.

Non-weight based dosing. A starting dose of approximately 0.2 mg/day (range, 0.15-0.30 mg/day) may be used without consideration of body weight, and increased gradually every 1-2 months by increments of approximately 0.1-0.2 mg/day.

Weight-based dosing. The recommended initial daily dose is not more than 0.006 mg/kg (6 μg/kg); the dose may be increased to a maximum of 0.0125 mg/kg (12.5 μg/kg) daily.

Drug Class

H01AC – Somatropin and somatropin agonists

Drug Unit

mg/vial

Food Warning

No known interactions

Included In
Health Insurance Plan

Humatrope sometimes is covered by health insurance if considered medically necessary, but some patients have had coverage denied. The Magic Foundation offers help making the case for coverage or appealing a denial, and outlines patients’ experiences getting approval.

Interacting Drug

Inhibitors of 11ß-Hydroxysteroid Dehydrogenase Type 1:
May require the initiation of glucocorticoid replacement therapy. Patients treated with glucocorticoid replacement for previously diagnosed hypoadrenalism may require an increase in their maintenance dosesGlucocorticoid Replacement Therapy:
Should be carefully adjustedCytochrome P450-Metabolized Drugs:
Monitor carefully if used with somatropinOral Estrogen:
Larger doses of somatropin may be required in womenInsulin and/or Oral/Injectable Hypoglycemic Agents:
May require adjustment 

Is Available Generically

No. There is currently no therapeutically equivalent version of Humatrope available.

Is Proprietary

Yes

Label Details

https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/019640s084lbl.pdf

Legal Status

Legal.

Is not subject to the Controlled Substances Act.

Manufacturer

Eli Lilly and Company

Maximum Intake

0.0125 mg/kg (12.5 μg/kg) daily

Mechanism of Action

Somatropin binds to the human growth hormone receptor (GHR). Upon binding, soatropin causes dimerization of GHR, activation of the GHR-associated JAK2 tyrosine kinase, and tyrosyl phosphorylation of both JAK2 and GHR. These events recruit and/or activate a variety of signaling molecules, including MAP kinases, insulin receptor substrates, phosphatidylinositol 3′ phosphate kinase, diacylglycerol, protein kinase C, intracellular calcium, and Stat transcription factors. These signaling molecules contribute to the GH-induced changes in enzymatic activity, transport function, and gene expression that ultimately culminate in changes in growth and metabolism.

Non Proprietary Name

Somatropin

Overdosage

Short-term overdosage could lead initially to hypoglycemia and subsequently to hyperglycemia. Furthermore, overdose with somatropin is likely to cause fluid retention.

Long-term overdosage could result in signs and symptoms of gigantism and/or acromegaly consistent with the known effects of excess growth hormone

Pregnancy Category

 

AU TGA pregnancy category B2: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals are inadequate or may be lacking, but available data show no evidence of an increased occurrence of fetal damage.

US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

Pregnancy Warning

Use is not recommended unless clearly needed.

Animal studies did not show any teratogenicity or adverse effects on gestation, morphogenesis, parturition, lactation, postnatal development, or reproductive capacity of the offspring; a slight increase in fetal death and increased body weight of pups, and reduced pregnancy rate, increased litter size, irregular estrus cycles, and decreased sperm motility in the parents were seen. There are no controlled data in human pregnancy.

Prescribing Info

https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/019640s084lbl.pdf

Prescription Status

Prescription drug

Proprietary Name

Humatrope

Related Drugs

Tesamorelin, Mecasermin rinfabate, Sermorelin, Mecasermin, Somatrem

RxCUI

197123

Warning

 

Acute Critical Illness: Potential benefit of treatment continuation should be weighed against the potential risk.

Prader-Willi Syndrome in Children: Evaluate for signs of upper airway obstruction and sleep apnea before initiation of treatment for GHD. Discontinue treatment if these signs occur.

Neoplasm: Monitor patients with preexisting tumors for progression or recurrence. Increased risk of a second neoplasm in childhood cancer survivors treated with somatropin – in particular meningiomas in patients treated with radiation to the head for their first neoplasm.

Impaired Glucose Tolerance and Diabetes Mellitus: May be unmasked. Periodically monitor glucose levels in all patients. Doses of concurrent antihyperglycemic drugs in diabetics may require adjustment.

Intracranial Hypertension: Exclude preexisting papilledema. May develop and is usually reversible after discontinuation or dose reduction.

Hypersensitivity: Serious hypersensitivity reactions may occur. In the event of an allergic reaction, seek prompt medical attention.

Fluid Retention (i.e., edema, arthralgia, carpal tunnel syndrome – especially in adults): May occur frequently. Reduce dose as necessary.

Hypoadrenalism: Monitor patients for reduced serum cortisol levels and/or need for glucocorticoid dose increases in those with known hypoadrenalism.

Hypothyroidism: May first become evident or worsen.

Slipped Capital Femoral Epiphysis: May develop. Evaluate children with the

onset of a limp or hip/knee pain.

Progression of Preexisting Scoliosis: May develop.

Pancreatitis: Consider pancreatitis in patients with persistent severe abdominal pain.

 

Links:

https://www.humatrope.com/
https://www.drugs.com/pro/humatrope.html
https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a774e1ae-3997-49ee-8b0e-99a2b315d409
https://www.drugbank.ca/drugs/DB00052

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