Skip to Content
Find out more about colorectal cancer treatments

Pegvisomant

Pronunciation

(peg VI soe mant)

Index Terms

  • B2036-PEG

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Solution Reconstituted, Subcutaneous:

Somavert: 10 mg (1 ea); 15 mg (1 ea); 20 mg (1 ea); 25 mg (1 ea); 30 mg (1 ea)

Brand Names: U.S.

  • Somavert

Pharmacologic Category

  • Growth Hormone Receptor Antagonist

Pharmacology

An analogue of human growth hormone, pegvisomant selectively binds to growth hormone (GH) receptors, blocking the binding of endogenous GH, leading to decreased serum concentrations of insulin-like growth factor-1 (IGF-I) and other GH-responsive proteins. Pegvisomant is made up of a recombinant DNA protein covalently bound to polyethylene glycol (PEG) polymers.

Absorption

SubQ: 57%

Distribution

7 L

Excretion

Urine (<1%)

Time to Peak

Serum: 33 to 77 hours

Half-Life Elimination

~60 to 138 hours (~2.5 to 6 days)

Use: Labeled Indications

Acromegaly: Treatment of acromegaly in patients who have had an inadequate response to surgery or radiation therapy, or for whom these therapies are not appropriate.

Contraindications

There are no contraindications listed in the manufacturer's labeling.

Dosing: Adult

Acromegaly: SubQ: Initial loading dose: 40 mg; maintenance dose: 10 mg once daily following initial loading dose; doses may be adjusted by 5 mg increments or decrements in 4- to 6-week intervals based on IGF-I concentrations (maximum maintenance dose: 30 mg daily)

Dosing: Geriatric

Refer to adult dosing.

Dosing: Renal Impairment

There are no dosage adjustments provided in the manufacturer’s labeling (has not been studied).

Dosing: Hepatic Impairment

At initiation of therapy:

Normal liver function test (LFT): Initiate therapy; monitor LFT monthly for first 6 months, quarterly for next 6 months, then biannually the following year.

Baseline LFT elevated but ≤3 x ULN: May initiate therapy with monthly evaluation of LFT for 1 year then biannually the following year.

Baseline LFT >3 times ULN: Do not initiate treatment without comprehensive work-up to determine cause; monitor closely if treatment is started.

With ongoing therapy:

LFT ≥3 x but <5 x ULN without signs/symptoms of hepatitis, hepatic injury, or increase in total bilirubin: Continue treatment, but monitor LFT weekly for further increases; perform comprehensive hepatic work-up to rule out alternative cause of hepatic dysfunction

LFT ≥5 x ULN or transaminase ≥3 x ULN associated with any increase in total bilirubin (with or without signs/symptoms of hepatitis or other liver injury): Discontinue immediately and perform comprehensive hepatic work-up. If LFTs return to normal, may cautiously consider restarting therapy with frequent LFT monitoring.

Signs or symptoms of hepatitis or hepatic injury: Perform comprehensive hepatic work-up; discontinue permanently if liver injury is confirmed.

Reconstitution

Remove vial and diluent from refrigerator approximately 10 minutes prior to administration. Reconstitute each vial with 1 mL SWFI. Aim diluent along glass wall of vial, do not inject diluent directly on powder. Gently swirl solution in order to dissolve powder; do not invert the vial or shake the solution. After reconstitution, each vial will contain 10, 15, 20, 25, or 30 mg/mL of pegvisomant. Use only 1 dose per vial.

Administration

For SubQ administration only; to minimize the risk for lipohypertrophy, rotate injection site daily; if 2 injections are required, select a different injection site for second injection; may administer in upper arm, thigh, abdomen, or buttocks; do not rub injection site. Do not use on area of skin with rash, lumps, bruising or on broken skin. The manufacturer recommends the initial dose be administered under the supervision of prescribing healthcare provider.

Storage

Store intact vials under refrigeration at 2°C to 8°C (36°F to 46°F); protect from freezing. Following reconstitution, use within 6 hours. Do not use reconstituted solution if cloudy or foaming.

Drug Interactions

Analgesics (Opioid): May diminish the therapeutic effect of Pegvisomant. Monitor therapy

Blood Glucose Lowering Agents: Pegvisomant may enhance the hypoglycemic effect of Blood Glucose Lowering Agents. Monitor therapy

Pegloticase: May diminish the therapeutic effect of Pegvisomant. Monitor therapy

Somatostatin Analogs: May enhance the adverse/toxic effect of Pegvisomant. Specifically, this combination may increase the risk for significant elevations of liver enzymes. Monitor therapy

Test Interactions

Interferes with measurement of serum GH concentrations by available GH assays; commercially available GH assays will overestimate true GH levels

Adverse Reactions

>10%:

Central nervous system: Pain (8% to 14%)

Gastrointestinal: Diarrhea (≤14%), nausea (≤14%)

Hepatic: Abnormal hepatic function tests (4% to 12%; >10 x ULN: ≤1%; ≤15 times ULN: <2%)

Immunologic: Antibody development (17%; non-neutralizing anti-GH antibodies; relevance unknown)

Infection: Infection (≤23%)

Local: Injection site reaction (4% to 11%)

Respiratory: Flu-like symptoms (4% to 12%)

1% to 10%:

Cardiovascular: Chest pain (≤8%), hypertension (≤8%), peripheral edema (≤8%)

Central nervous system: Dizziness (≤8%), paresthesia (≤7%)

Endocrine & metabolic: Lipohypertrophy (1%)

Neuromuscular & skeletal: Back pain (≤8%)

Respiratory: Sinusitis (≤8%)

Miscellaneous: Accidental injury (≤8%)

<1% (Limited to important or life-threatening): Anaphylactoid reaction, anaphylaxis, hypersensitivity reaction, increased serum alkaline phosphatase, tumor growth, weight gain

Warnings/Precautions

Concerns related to adverse effects:

• Hepatic effects: May increase liver function tests; transient but marked elevations (≤15 x upper limit of normal [ULN]) in transaminase levels, usually without accompanying hyperbilirubinemia, have been reported with use; transaminase levels often normalized following interruption of therapy; use with caution in patients with hepatic impairment; monitor hepatic function periodically during therapy; discontinue use immediately with confirmed liver injury.

• Lipohypertrophy: May occur following administration; daily rotation of injection site may prevent or reduce incidence.

Disease-related concerns:

• Diabetes: Use with caution in patients with diabetes mellitus; may affect glucose metabolism; monitor closely; dosage adjustments of antidiabetic therapy may be necessary.

Other warnings/precautions:

• Administration: The manufacturer recommends the initial dose be administered under the supervision of prescribing health care provider.

• Monitoring: Interferes with commercially available GH assays; do not make dose adjustments based on serum GH concentrations reported from assays; use insulin-like growth factor I (IGF-I) levels to adjust therapy.

Monitoring Parameters

GH-secreting tumor size, serum glucose in diabetic patients, serum IGF-I (every 4 to 6 weeks after initial dose and dosage change, every 6 months when normalized, and when multiple injections are converted to single daily injections).

Liver function tests (ALT, AST, total bilirubin, and alkaline phosphatase levels):

Baseline:

Normal: Monthly for first 6 months, quarterly for next 6 months, biannually for the next year

Elevated, but ≤3 x ULN: Monitor monthly for at least 1 year, then biannually for the next year

>3 x ULN: Withhold treatment; perform comprehensive liver function evaluation (rule out cholelithiasis or choledocholithiasis); if appropriate for treatment, closely monitor hepatic function and clinical status.

During therapy:

≥3 x but <5 x ULN without signs/symptoms of hepatitis, hepatic injury or increase in total bilirubin: Monitor weekly for further increases; perform comprehensive hepatic work-up

≥5 x ULN or transaminase ≥3 x ULN associated with any increase in total bilirubin (with or without signs/symptoms of hepatitis or other liver injury): Comprehensive hepatic work-up. If appropriate for treatment monitor closely

Pregnancy Risk Factor

C

Pregnancy Considerations

Adverse events have been observed in some animal reproduction studies.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience diarrhea, flu-like symptoms, back pain, nausea, rhinorrhea, or rhinitis. Have patient report immediately to prescriber signs of infection, signs of liver problems (dark urine, feeling tired, lack of appetite, nausea, abdominal pain, light-colored stools, vomiting, or yellow skin or eyes), severe dizziness, passing out, burning or numbness feeling, angina, severe headache, bruising, bleeding, swelling of arms or legs, or severe injection site pain or irritation (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

Hide