Absorption
Somatropin C max with concentrations of 5.3 mg/mL is approximately 23 ng/mL. C max with concentrations of 1.3 mg/mL is approximately 17.4 ng/mL. Following a 0.03 mg/kg subcutaneous injection of Genotropin 1.3 mg/mL, about 80% was systemically available compared with that available following IV dosing.

Distribution
Vd is approximately 1.3 L/kg.

Metabolism
Somatropin undergoes classical protein catabolism in both liver and kidneys.

Elimination
The half-life is approximately 0.4 h (IV) and approximately 3 h (subcutaneous). Mean Cl of subcutaneous administration is about 0.3 L/h/kg.

Special Populations
Renal Function Impairment
Patients with chronic renal failure (CRF) and end-stage renal disease have decreased Cl compared with healthy individuals.

Children
Genotropin
Pharmacokinetics similar in children and adults.

Gender
Genotropin
Bioavailability similar in men and women.

Corticosteroids
Somatropin may interfere with the metabolic conversion of cortisol and cortisone to their active metabolites. Glucocorticoids may inhibit growth-promoting effects of somatropin.

CYP-450 substrates (eg, anticonvulsants, cyclosporine)
Somatropin may alter the Cl of drugs metabolized by CYP liver enzymes.

Insulin, oral hypoglycemic agents
Because somatropin decreases insulin sensitivity, diabetic patients receiving drug therapy may require adjustments in the insulin or oral hypoglycemic dosage when somatropin is started or stopped.

Oral estrogens
Larger doses of somatropin may be required in women receiving oral estrogens.

1.Genotropin禁用於有任何腫瘤跡象時，而且開始治療之前必須已經完成抗腫瘤治療。
2.Genotropin禁用於促進骨骨后板已閉合兒童之生長。
3.Genotropin禁用於開心手術、腹部手術、多重意外創傷、急性呼吸衰竭或類似狀況後發生併發症的急性重症病人。
4.對主成分或任何賦形劑過敏者。

1.Somatropin會引起胰島素抗性，有些病人會發生高血糖。因此應觀察病人是否有葡萄糖不耐症的跡象。
2.患有內分泌疾病的病人，包括生長激素缺乏症的病人，可能比一般人更容易發生髖部骨骨后脫位。病童若在somatropin治療期間發生跛行現象，應就醫檢查。
3.使用somatropin治療期間，倘若患者出現上呼吸道阻塞的徵候(包括開始打鼾或打鼾增加)，應中止治療並做新的耳鼻喉科評估。