Medically reviewed by Drugs.com. Last updated on Oct 23, 2021.
(SOE ma PAS i tan)
- Growth Hormone
Somapacitan is a human growth hormone analog of recombinant DNA origin with a single substitution in the amino acid backbone to which an albumin-binding moiety has been attached. Somapacitan binds to a dimeric growth hormone receptor in the cell membrane of target cells resulting in multiple pharmacodynamic effects; some of these effects are primarily mediated by insulin-like growth factor 1 produced in the liver, while others are primarily a consequence of the direct effects of somapacitan.
Vd: ~14.6 L.
Extensive; via proteolytic cleavage of the linker sequence between the peptide backbone and albumin binder sidechain.
Urine: ~81%; feces: ~13%.
Time to Peak
Single dose: 4 to 24 hours (dose dependent); steady state is achieved after 1 to 2 weeks of once weekly SubQ administration (Rasmussen 2014; Rasmussen 2016).
Duration of Action
≥7 days (Rasmussen 2014; Rasmussen 2016).
~2 to 3 days.
Special Populations: Renal Function Impairment
Drug exposure increases with decreasing eGFR (AUC increased by 1.75-fold in severe renal impairment).
Special Populations: Hepatic Function Impairment
Cmax was 3.52-fold higher in patients with moderate hepatic impairment compared to patients with normal hepatic function.
Special Populations: Elderly
Patients ≥65 years of age have greater drug exposure than patients <65 years of age at the same dose level.
Use: Labeled Indications
Growth hormone deficiency: Replacement of endogenous growth hormone in adults with growth hormone deficiency.
Hypersensitivity to somapacitan or any component of the formulation; acute critical illness after open heart surgery, abdominal surgery, or multiple accidental trauma; acute respiratory failure; active malignancy; active proliferative or severe nonproliferative diabetic retinopathy.
Growth hormone deficiency:
SubQ: Initial: 1.5 mg once weekly; may increase dose by 0.5 to 1.5 mg/week every 2 to 4 weeks based on clinical response and insulin-like growth factor 1 (IGF-1) levels; reduce dose if needed for adverse reactions or elevated IGF-1 levels. Maximum dose: 8 mg/week.
Duration of therapy: Consider discontinuing therapy if no apparent benefits are achieved after 12 to 18 months; therapy may be continued indefinitely if benefits are achieved (AACE/ACE [Yuen 2019]).
Missed doses: Administer missed dose as soon as possible within 3 days; resume usual schedule thereafter. If >3 days have passed since the missed dose, skip dose and administer next dose on the next regular dosing day.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
SubQ: Initial: 1 mg once weekly; adjust dose in smaller increments.
SubQ: For SubQ administration into the abdomen or thigh. Rotate injection site weekly to avoid lipohypertrophy. Prime unused pen devices before injecting. Once injected, keep the needle in the skin for a count of 6 after the dose dial has returned to 0 mg before removing the needle to ensure the full dose has been administered. Pen device delivers doses from 0.05 to 4 mg in increments of 0.05 mg.
Store unopened prefilled pen in a refrigerator at 2°C to 8°C (36°F to 46°F) with the cap on and in the original carton to protect from light. After opening, store in a refrigerator at 2°C to 8°C (36°F to 46°F) for up to 6 weeks. Prefilled pen (opened or unopened) may be temporarily exposed to room temperature up to 25°C (77°F) for a total of 72 hours. Do not freeze. Discard prefilled pen if it has been frozen or kept >30°C (86°F). Avoid exposing pen to direct or excessive heat or sunlight.
Antidiabetic Agents: Hyperglycemia-Associated Agents may diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy
Cortisone: May diminish the therapeutic effect of Growth Hormone Analogs. Growth Hormone Analogs may decrease serum concentrations of the active metabolite(s) of Cortisone. Monitor therapy
Estrogen Derivatives: May diminish the therapeutic effect of Growth Hormone Analogs. Management: Initiate somapacitan at 2 mg once weekly in patients receiving oral estrogens. Monitor for reduced efficacy of growth hormone analogs; increased doses may be required. Consider therapy modification
Macimorelin: Products that Affect Growth Hormone may diminish the diagnostic effect of Macimorelin. Avoid combination
PredniSONE: May diminish the therapeutic effect of Growth Hormone Analogs. Growth Hormone Analogs may decrease serum concentrations of the active metabolite(s) of PredniSONE. Monitor therapy
Thyroid Products: Growth Hormone Analogs may diminish the therapeutic effect of Thyroid Products. Monitor therapy
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
>10%: Endocrine & metabolic: Increased serum phosphate (18%)
1% to 10%:
Cardiovascular: Hypertension (3%), peripheral edema (3%)
Endocrine & metabolic: Adrenocortical insufficiency (3%), weight gain (3%)
Gastrointestinal: Dyspepsia (5%), vomiting (3%)
Hematologic & oncologic: Anemia (3%)
Nervous system: Dizziness (4%), sleep disorder (4%)
Neuromuscular & skeletal: Arthralgia (7%), back pain (10%), increased creatine phosphokinase in blood specimen (3% to 9%)
Respiratory: Tonsillitis (3%)
Concerns related to adverse effects:
• Fluid retention: Fluid retention may occur; manifestations of fluid retention, including edema, arthralgia, myalgia, and nerve compression syndromes (including carpal tunnel syndrome or paresthesias), are generally transient and dose dependent.
• Glucose tolerance: Somapacitan may decrease insulin sensitivity. Previously undiagnosed impaired glucose tolerance and overt diabetes mellitus may be detected; new-onset type 2 diabetes mellitus and exacerbation of preexisting diabetes mellitus may occur. Monitor glucose levels periodically in all patients; in patients with preexisting diabetes mellitus, adjustment of antidiabetic medications may be necessary.
• Hypersensitivity: Serious systemic hypersensitivity reactions, including anaphylactic reactions and angioedema, have been reported with use of growth hormone products.
• Intracranial hypertension: Intracranial hypertension (IH) with headache, nausea, papilledema, visual changes, and/or vomiting has been reported in patients treated with growth hormone products; symptoms usually occurred within the first 8 weeks of therapy and signs and symptoms of IH may rapidly resolve after discontinuation or reduction of dose. Funduscopic examination prior to initiation of therapy and periodically thereafter is recommended. Treatment should be discontinued in patients who develop papilledema; resuming treatment at a lower dose may be considered once IH-associated signs and symptoms have resolved.
• Lipoatrophy/Lipohypertrophy: Lipoatrophy or lipohypertrophy have been reported at injection sites when used at the same site for a prolonged period. Rotate injection sites to reduce risk.
• Neoplasm: Increased risk of malignancy progression in patients with active malignancy; any preexisting malignancy should be inactive and treatment complete prior to initiating therapy; discontinue therapy with evidence of recurrence or progression. Monitor patients with preexisting tumors for recurrence or progression of underlying disease. Monitor all patients for any malignant transformation of skin lesions.
• Pancreatitis: Pancreatitis has been reported with use of growth hormone products. Consider pancreatitis diagnosis if abdominal pain occurs.
• Acute critical illness: Somapacitan is contraindicated in patients with acute critical illness due to potential complications following open heart or abdominal surgery, multiple accidental trauma, or acute respiratory failure; these concerns are based on studies that showed increased mortality in critically ill patients without growth hormone deficiency who were receiving supraphysiologic doses of growth hormone. Safety of continuing growth hormone products used at lower doses (eg, for replacement therapy) has not been established during critical illness.
• Hepatic impairment: Use is not recommended in patients with severe hepatic impairment; dosage adjustment is required in patients with moderate hepatic impairment.
• Hypoadrenalism: Patients who have or are at risk for pituitary hormone deficiency(ies) may be at risk for reduced serum cortisol levels and/or unmasking of central (secondary) hypoadrenalism with somapacitan therapy; patients with previously diagnosed hypoadrenalism may require increased dosages of glucocorticoids due to the effects of somapacitan. Monitor for reduced serum cortisol levels and/or need to adjust glucocorticoid dosage.
• Hypothyroidism: Patients who have or are at risk for pituitary hormone deficiency(ies) may be at risk for reduced thyroid function (central hypothyroidism). Untreated/undiagnosed hypothyroidism may decrease response to therapy. Monitor thyroid function periodically and initiate/adjust thyroid replacement therapy as needed.
• Elderly: Patients ≥65 years of age may be more sensitive to the actions of somapacitan due to greater drug exposure than patients <65 years of age at the same dose level; lower starting doses and smaller dose increments are required.
Dosage form specific issues:
• Multiple-dose injection pens: According to the Centers for Disease Control and Prevention, pen-shaped injection devices should never be used for more than 1 person (even when the needle is changed) because of the risk of infection. The injection device should be clearly labeled with individual patient information to ensure that the correct pen is used (CDC 2012).
Monitor clinical response, serum insulin-like growth factor 1 (IGF-1), and side effects every 2 to 4 weeks during dose titration; IGF-1 levels should be checked 3 to 4 days after the prior dose. Once at maintenance dose, monitor serum IGF-1, fasting glucose, HbA1c, BMI, waist circumference/waist to hip ratio, thyroid function (free T4), adrenal function, lipid profile, BP, heart rate, clinical response, and side effects every 6 to 12 months; bone mineral density should be evaluated prior to therapy and dual-energy x-ray absorptiometry scan repeated every 1.5 to 3 years if initial bone scan is abnormal (AACE/ACE [Yuen 2019]; ES [Fleseriu 2016]; ES [Molitch 2011]).
Growth hormone replacement therapy may improve amenorrhea, dysmenorrhea, and fertility in females with growth hormone deficiency (information not specific to use of somapacitan) (Vila 2018).
During normal pregnancy, maternal production of endogenous growth hormone decreases as placental growth hormone production increases. Continued use of short-acting growth hormone replacement early in pregnancy in patients with growth hormone deficiency has not been associated with adverse pregnancy outcomes (information not specific to use of somapacitan) (Vila 2018).
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