Somapacitan (Monograph)

Drug class: Pituitary

Introduction

Recombinant human growth hormone attached to an albumin-binding moiety.

Uses for Somapacitan

Growth Hormone Deficiency in Adults

• Used for endogenous growth hormone (GH) replacement in adults with growth hormone deficiency (GHD).

• Guidelines support use of GH treatment in adults with GHD; benefits include improved body composition (e.g., decreased body fat, increased lean body mass), bone health, exercise capacity, and quality of life.

Growth Hormone Deficiency in Pediatric Patients

• Treatment of pediatric patients ≥2.5 years of age who have growth failure due to inadequate secretion of endogenous GH.

Somapacitan Dosage and Administration

General

Pretreatment Screening

• Perform funduscopic examination to exclude preexisting papilledema.

• Obtain baseline serum IGF-1 concentration.

Patient Monitoring

• Perform periodic funduscopic examination.

• In adults with GHD, experts recommend follow-up monitoring every 1–2 months; once maintenance dosing is achieved, clinical monitoring (e.g., serum IGF-1, fasting glucose, hemoglobin A1c, waist circumference) may occur at 6-12 month intervals.

• In pediatric patients, assess compliance and evaluate other causes of poor growth such as hypothyroidism, undernutrition, advanced bone age, and antibodies to recombinant human GH if patients experience failure to increase height velocity, particularly during the first year of treatment.

• When initiating somapacitan, closely monitor patients with preexisting type 1 diabetes mellitus, type 2 diabetes mellitus, or impaired glucose tolerance and adjust dosages of antihyperglycemic drugs as needed.

• Patients who were treated with somapacitan for GHD in childhood and whose epiphyses are closed should be reevaluated before continuing the drug.

Dispensing and Administration Precautions

• Somapacitan therapy should be supervised by a healthcare provider who is experienced in the diagnosis and management of patients with the conditions for which the drug is indicated.

Administration

Sub-Q Administration

Available in prefilled, single-patient use pen devices.

Administer weekly by sub-Q injection into the upper arms, abdomen, thigh, or buttocks.

Rotate injection sites weekly.

If a dose is missed, administer the missed dose within 3 days, then resume once-weekly dosing for the next dose at the regularly scheduled day.

If >3 days have passed since the missed dose, skip dose and administer next dose on theregularly scheduled day.

Dosage

Pediatric Patients

Growth Hormone Deficiency

Treatment-naive patients or patients switching from daily somatropin therapy

Sub-Q

Pediatric patients ≥2.5 years of age: 0.16 mg/kg (based on actual body weight) once weekly.

Individualize dosage based on growth response.

When switching from daily human GH to once-weekly somapacitan-beco, select the preferred day for the weekly dose. Take the final dose of daily treatment on the day before (or at least 8 hours before) the first dose of somapacitan-beco.

When switching from a weekly human GH to once-weekly somapacitan-beco, continue once weekly dosing schedule.

Adults

Growth Hormone Deficiency

Treatment-naive patients or patients switching from daily somatropin therapy

Sub-Q:

1.5 mg once weekly.

Titrate by 0.5- to 1.5-mg increments every 2–4 weeks until clinical response achieved.

Maximum: 8 mg once weekly.

Special Populations

Hepatic Impairment

Mild: No dosage adjustment necessary.

Moderate: Initial dosage of 1 mg once weekly in adults. Titrate using smaller dosage increments; maximum dosage of 4 mg once weekly. Not recommended in pediatric patients with moderate hepatic impairment.

Severe: Not recommended.

Renal Impairment

No dosage recommendations at this time.

Geriatric Patients

Patients ≥65 years of age: Initial dosage 1 mg once weekly. Titrate using smaller dosage increments.

Women Receiving Oral Estrogen

Initial dosage of somapacitan in women taking oral estrogen is 2 mg once weekly. (See Adult Growth Hormone Deficiency under Dosage and Administration for titration, monitoring, and maximum dosage recommendations.)

Cautions for Somapacitan

Contraindications

• Acute critical illness after open heart surgery, abdominal surgery or multiple accidental trauma, or those with acute respiratory failure.

• Hypersensitivity to somapacitan-beco or any of the excipients.

• Active malignancy.

• Active proliferative or severe non-proliferative diabetic retinopathy.

• Pediatric patients with closed epiphyses.

• Pediatric patients with Prader-Willi syndrome who are severely obese, have a history of upper airway obstruction or sleep apnea or have severe respiratory impairment due to risk of sudden death.

Warnings/Precautions

Warnings

Increased Mortality in Patients with Acute Critical Illness

Increased mortality reported in patients continuing somatropin while experiencing acute critical illness following open heart surgery, abdominal surgery or multiple accidental trauma, or those with acute respiratory failure.

Safety of continuing somapacitan in patients receiving replacement doses for approved indications who develop these conditions not established.

Not indicated for treatment of non-GH deficient adults.

Severe Hypersensitivity

Serious hypersensitivity reactions, including anaphylaxis and angioedema, reported during postmarketing experience with somatropin. Advise patients to immediately seek medical attention if an allergic reaction occurs.

Contraindicated in patients with known hypersensitivity to somatropin or any excipients in somapacitan.

Increased Risk of Neoplasms - Active Malignancy

Increased risk of malignancy progression with somatropin treatment in patients with active malignancy.

Complete malignancy treatment; preexisting malignancy should be inactive before initiating somapacitan.

Discontinue if malignancy recurs.

Increased Risk of Neoplasms – Risk of Second Neoplasm in Pediatric Patients

Increased risk of a second neoplasm reported in pediatric cancer survivors with acquired GHD who were treated with somatropin following radiation to the brain/head for their first neoplasm; intracranial tumors were most common.

Monitor patients with a history of GHD secondary to intracranial neoplasm while on GH therapy for progression or recurrence of the tumor.

Increased Risk of Neoplasms – New Malignancy during Treatment

Consider risks and benefits of starting somapacitan in children with certain rare genetic causes of short stature associated with an intrinsically increased risk of developing malignancies; monitor these patients carefully for neoplasm development.

Risk of malignant changes of preexisting nevi.

Monitor for increased growth, or potential malignant changes, of preexisting nevi.

Advise patients to report skin pigmentation changes or appearance changes of pre-existing nevi.

Glucose Intolerance and Diabetes Mellitus

May decrease insulin sensitivity and/or unmask undiagnosed impaired glucose tolerance or type 2 diabetes mellitus (DM).

Monitor glucose levels periodically, especially in those with risk factors for type 2 DM.

Monitor patients with preexisting type 1 or type 2 DM or impaired glucose tolerance; adjust dosage of antihyperglycemic drugs as needed.

Intracranial Hypertension

Intracranial hypertension with papilledema, visual changes, headache, nausea, and/or vomiting reported.

Symptoms occur within 8 weeks; signs and symptoms resolve rapidly after drug cessation or dosage reduction.

Perform funduscopic examination before initiating treatment. If symptoms (e.g., visual changes, headache, nausea and/or vomiting) occur during therapy, perform fundoscopic examination.

Discontinue treatment if papilledema is observed. May restart treatment at a lower dose after signs and symptoms have resolved.

Fluid Retention

Fluid retention may occur, is usually transient, and dose-dependent.

Hypoadrenalism

Patients with, or are at risk for, pituitary hormone deficiency may be at risk for reduced serum cortisol levels and/or unmasking of central (secondary) hypoadrenalism.

Patients treated with glucocorticoid replacement may require an increase in their maintenance or stress doses.

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

Hypothyroidism

Undiagnosed or untreated hypothyroidism may prevent optimal response.

Central (secondary) hypothyroidism may first become evident or worsen during treatment.

Perform periodic thyroid function tests; initiate or adjust thyroid hormone replacement therapy.

Slipped Capital Femoral Epiphysis in Pediatric Patients

Slipped capital femoral epiphysis may occur more frequently in patients undergoing rapid growth. Evaluate pediatric patients with onset of a limp or complaints of persistent hip or knee pain.

Progression of Preexisting Scoliosis in Pediatric Patients

Because somatropin increases growth rate, progression of preexisting scoliosis can occur in patients who experience rapid growth.

Somatropin has not been shown to increase the occurrence of scoliosis.

Monitor patients with a history of scoliosis for disease progression.

Pancreatitis

Pancreatitis reported; risk may be greater in pediatric patients than adults.

Consider pancreatitis in patients who develop persistent severe abdominal pain.

Lipohypertrophy/Lipoatrophy

Rotate injection sites to reduce the risk of lipohypertrophy or lipoatrophy.

Sudden Death in Pediatric Patients with Prader-Willi Syndrome

Fatalities reported after initiating therapy with somatropin in pediatric patients with Prader-Willi syndrome who had at least one of the following risk factors: severe obesity, history of upper airway obstruction or sleep apnea, or unidentified respiratory infection.

Males may be at greater risk than females.

Somapacitan is not indicated for treatment of pediatric patients who have growth failure due to genetically confirmed Prader-Willi syndrome.

Immunogenicity

No anti-somapacitan-beco antibodies detected in clinical trials of adult patients with GHD.

Anti-somapacitan-beco antibodies detected in approximately 12% of pediatric patients with GHD receiving the drug.

No clinically important effects on pharmacokinetics, pharmacodynamics, safety, or effectiveness observed in patients who developed such antibodies; no neutralizing antibodies detected.

Laboratory Tests

Increased levels of phosphate, alkaline phosphatase, and parathyroid hormone may occur.

Specific Populations

Pregnancy

No available data on somapacitan to inform a risk of major birth defects or other adverse pregnancy outcomes.

No teratogenicity observed in animal studies.

Available data for somatropin have not identified a risk of major birth defects or other adverse pregnancy outcomes.

Lactation

No data on the presence of somapacitan in human milk, effects on breastfed infants, or effects on human milk production.

Data indicate somatropin does not increase normal human milk GH concentrations.

No adverse effects on breastfed infants reported with somatropin.

Consider developmental and health benefits of breastfeeding along with mother’s clinical need for somapacitan and any potential adverse effects on the breastfed infant from the drug or underlying maternal condition.

Pediatric Use

Safety and efficacy in pediatric patients <2.5 years of age not established.

Risks of GH therapy specific to pediatric patients include risk of sudden death in pediatric patients with Prader-Willi syndrome, increased risk of second neoplasm in pediatric cancer survivors treated with radiation to the brain and/or head, slipped capital femoral epiphysis, progression of preexisting scoliosis, and pancreatitis.

Geriatric Use

Limited data in patients ≥65 years of age.

Geriatric patients ≥65 years of age have a higher exposure compared to younger subjects at the same dosage, may be more sensitive, and may be at increased risk for adverse effects. Initial dosage of 1 mg once weekly recommended; use smaller increments when increasing dose.

Hepatic Impairment

Similar exposure between adults with normal and mild hepatic impairment.

Higher exposure was observed in adults with moderate hepatic impairment. Safety and efficacy in patients with severe hepatic impairment not established.

In adults with moderate hepatic impairment, initial dosage of 1 mg once weekly recommended; use smaller increments when increasing the dose; maximum recommended dosage 4 mg once weekly.

No dosage adjustment recommended in pediatric patients with mild hepatic impairment. Higher systemic exposure is expected in pediatric patients with moderate and severe hepatic impairment; therefore, sompacitan is not recommended in these patients.

Renal Impairment

Higher exposure observed in patients with severe renal impairment or those requiring hemodialysis.

Common Adverse Effects

Adverse effects (≥2%) in adults with GHD: back pain, arthralgia, dyspepsia, sleep disorder, dizziness, tonsillitis, peripheral edema, vomiting, adrenal insufficiency, hypertension, increased blood creatine, weight increase, anemia.

Adverse effects (≥5%) in pediatric patients with GHD: nasopharyngitis, headache, pyrexis, pain in extremity, injection site reaction.

Drug Interactions

Not known to be metabolized by CYP isoenzymes or other drug metabolizing enzymes; however, GH can induce changes in CYP activity.

Drugs Affecting or Affected by Hepatic Microsomal Enzymes

Carefully monitor patients receiving concomitant therapy with drugs metabolized by CYP isoenzymes because somapacitan may alter clearance of these drugs.

Specific Drugs

Somapacitan Pharmacokinetics

Absorption

Plasma Concentrations

Maximum plasma levels occur 4-24 hours post dose.

Steady state occurs in 1–2 weeks following once weekly administration.

Lower exposure in females, especially those taking oral estrogen, compared with males.

Geriatric patients ≥65 years of age: Higher exposure compared to younger patients.

Hepatic impairment in adults: Exposure similar for patients with normal function and mild impairment (Child-Pugh class A). Exposure higher in adults with moderate impairment (Child-Pugh class B). Not evaluated in severe impairment (Child-Pugh class C).

Hepatic impairment in pediatric patients: Higher systemic exposure is expected in patients with moderate and severe hepatic impairment.

Renal impairment: Exposure increases with decreasing eGFR; most pronounced with severe renal impairment (GFR <30 mL/minute) and hemodialysis.

Distribution

Extent

Not known whether somapacitan is distributed into human mik.

Plasma Protein Binding

>99%.

Elimination

Metabolism

Metabolized via proteolytic cleavage of the linker sequence between the peptide backbone and albumin binder sidechain.

Elimination Route

Excreted via the urine (81%) and feces (13%); not excreted intact.

Half-life

Approximately 2 to 3 days.

Stability

Storage

Parenteral

Prefilled pen

2–8°C. Do not freeze; do not use if frozen.

Protect from light and store in original carton.

Avoid direct or excessive heat; discard if kept above 30°C.

Before first use (unopened): 2–8°C until expiration date; up to 25°C maximum 72 hours.

After first use (opened): 2–8°C up to 6 weeks; up to 25°C maximum 72 hours.

Actions

• Human growth hormone (hGH) analog with a single substitution in the amino acid backbone to which an albumin-binding moiety is attached.

• Albumin-binding moiety reduces clearance and extends half-life and duration of action.

• Binds to hGH receptor in cell membrane of target cells resulting in a cascade of pharmacodynamic effects (i.e., IGF-1 effect) that increases muscle protein synthesis, lipolysis with catabolic effects, hepatic gluconeogenesis and glycogenolysis via GH, and inhibition of gluconeogenesis via IGF-1.

Advice to Patients

• Advise patients to read the FDA-labeled patient information.

• Advise patients against any reuse or sharing, and proper disposal of pens and needles in an appropriate container.

• Inform patients on how to administer somapacitan and what to do for missed doses.

• Advise patients to report marked changes in skin pigmentation or changes in the appearance of preexisting nevi.

• Advise patients that fluid retention may occur and to contact their healthcare provider if symptoms (e.g., edema, arthralgia, myalgia, nerve compression syndromes including carpal tunnel syndrome/paresthesia) occur.

• Advise patients that pancreatitis may develop and to report any new onset abdominal pain to their healthcare provider.

• Advise patients that hypoadrenalism may develop and to report hyperpigmentation, extreme fatigue, dizziness, weakness, or weight loss to their healthcare provider.

• Advise patients that periodic thyroid function tests may be required.

• Advise patients that intracranial hypertension may occur and to immediately report any visual changes, headache, and nausea and/or vomiting to their healthcare provider.

• Advise patients that hypersensitivity reactions (anaphylaxis and angioedema) are possible, and to seek prompt medical attention if an allergic reaction occurs.

• Advise patients that new-onset impaired glucose intolerance/type 2 diabetes mellitus or exacerbation of preexisting diabetes mellitus can occur and to monitor blood glucose.

• Advise patients to rotate injection sites to decrease the risk of lipohypertrophy or lipoatrophy.

• Advise patients to inform their clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs and dietary or herbal supplements, as well as any concomitant illnesses.

• Advise women to inform their clinicians if they are or plan to become pregnant or plan to breast-feed.

• Inform patients of other important precautionary information.

Additional Information

The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer’s labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

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