Pharmacological properties - Omnitrope Somatropin by Sandoz
Somatropin has a pronounced effect on the metabolism of fats, proteins and carbohydrates. In children with growth hormone deficiency, somatropin stimulates the longitudinal growth of skeletal bones by acting on the epiphysis plates of the tubular bones. In both adults and children, somatropin helps to improve body shape by increasing muscle mass and reducing body fat. Visceral adipose tissue is especially sensitive to the action of somatropin. In addition to enhancing lipolysis, somatropin inhibits the supply of triglycerides to body fat.
Under the action of somatropin, the concentration of insulin-like growth factor I (IGF-I) and its binding protein, insulin-like growth factor-binding protein (IGFBP), increases.
Somatropin induces low density lipoprotein (LDL) receptors in the liver and changes the profile of lipids and lipoproteins in the blood. In general, the use of somatropin in patients with growth hormone deficiency leads to a decrease in blood LDL and apolipoprotein B.
There is also a decrease in cholesterol concentration
Somatropin stimulates insulin release, but fasting glucose concentration usually remains unchanged. Children with hypopituitarism may develop fasting hypoglycemia. Somatropin may improve such condition.
Water and mineral metabolism
Growth hormone deficiency is associated with decreased plasma and extracellular volumes. Both are rapidly increased after treatment with somatropin. Somatropin induces the retention of sodium, potassium and phosphorus.
Somatropin stimulates bone metabolism. Long-term administration of somatropin to growth hormone deficient patients with osteopenia results in an increase in bone mineral content and density.
Long-term somatropin replacement therapy can improve muscle strength and physical endurance.
Somatropin also increases cardiac output, but the mechanism has yet to be clarified. A decrease in peripheral vascular resistance may contribute to this effect.
Absorption - The bioavailability of subcutaneously injected somatropin is approximately 80% both in healthy subjects and growth hormone deficient patients.
After subcutaneously injection at a dose of 5 mg to healthy volunteers, plasma Cmax and Tmax were 72 ± 28 μg/L and 4±2 hours, respectively.
In adults with growth hormone deficiency, the average T1/2 of intravenously injected somatropin is about 0.4 hours. However, after subcutaneous administration, T1/2 reaches 3 hours.
Use in Specific Populations
The absolute bioavailability of somatropin after subcutaneous administration does not differ in men and women.
There is no data on the effect of somatropin on the pharmacokinetic parameters of age, race, impaired liver, kidney or heart function.