Overview
11 DESCRIPTION Pegvisomant is an analog of human growth hormone (GH) of recombinant DNA origin that acts as a GH receptor antagonist. It contains 191 amino acid residues. The molecular weight of pegvisomant is 22 kDa. The molecular weight of the PEG portion of pegvisomant is approximately 5 kDa. The predominant molecular weights of pegvisomant are thus approximately 42, 47, and 52 kDa.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Pegvisomant selectively binds to growth hormone (GH) receptors on cell surfaces, where it blocks the binding of endogenous GH, and thus interferes with GH signal transduction. Inhibition of GH action results in decreased serum concentrations of IGF-1, as well as other GH-responsive serum proteins such as free IGF-1, the acid-labile subunit of IGF-1 (ALS), and insulin-like growth factor binding protein-3 (IGFBP-3). 12.2 Pharmacodynamics Pegvisomant binds selectively to the GH receptor, and does not cross-react with 19 other cytokine receptors tested, including prolactin. Pegvisomant leads to decreased serum concentrations of IGF-1, free IGF-1, ALS, and IGFBP-3 [see Clinical Studies (14, Figure 1) ] . 12.
Indications
- 1 INDICATIONS AND USAGE SOMAVERT is indicated for the treatment of acromegaly in patients who have had an inadequate response to surgery or radiation therapy, or for whom these therapies are not appropriate. The goal of treatment is to normalize serum insulin-like growth factor-1 (IGF-1) levels. SOMAVERT is a growth hormone receptor antagonist indicated for the treatment of acromegaly in patients who have had an inadequate response to surgery or radiation therapy, or for whom these therapies are not appropriate.
Common Doses
- 40 mg
- 10 mg
- 5 mg
- 30 mg
Dosage
2 DOSAGE AND ADMINISTRATION • Administer a 40 mg loading dose subcutaneously under physician supervision. ( 2.1 ) • After proper injection instruction, on day after loading dose, patients or caregivers begin daily subcutaneous injections of 10 mg. ( 2.1 ) • Adjust dosage in 5 mg increments or decrements until serum IGF-1 concentrations are maintained within age-adjusted normal range. Do not adjust dosage based on growth hormone (GH) levels or signs or symptoms of acromegaly. ( 2.1 ) • Dosage range is 10 mg to 30 mg once daily. ( 2.
Contraindications
- 4 CONTRAINDICATIONS None. None. ( 4 )
Side Effects
- 6 ADVERSE REACTIONS Clinically significant adverse reactions that appear in other section of the labeling include: • Hypoglycemia Associated with GH Lowering in Patients with Diabetes Mellitus [see Warnings and Precautions (5.1) ] • Liver Toxicity [see Warnings and Precautions (5.2) ] • Cross-Reactivity with GH Assays [see Warnings and Precautions (5.3) ] • Lipohypertrophy [see Warnings and Precautions (5.4) ] • Systemic Hypersensitivity [see Warnings and Precautions (5.5) ] Elevations of serum concentrations of ALT and AST greater than ten times the ULN were reported in two patients (0.
Interactions
- 7 DRUG INTERACTIONS • Insulin and/or Oral hypoglycemic Agents: Patients with acromegaly and with diabetes mellitus may require careful monitoring and dose reductions of insulin and/or oral hypoglycemic agents. ( 5.2 , 7.1 ) • Opioids: Patients on opioids may need higher SOMAVERT doses to achieve appropriate IGF-1 suppression. ( 7.2 ) 7.1 Insulin and/or Oral Hypoglycemic Agents After initiation of SOMAVERT, patients with acromegaly and diabetes mellitus treated with insulin and/or oral hypoglycemic agents may require dose reductions of insulin and/or oral hypoglycemic agents [see Warnings and...