Pegvisomant (1 brand name, 1 dosage form, 1 route)
Available dosage forms: INJECTABLE.
Routes of administration: SUBCUTANEOUS.
Brand Names
- SOMAVERT
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.
Contraindications
None.
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 (0.8%) exposed to SOMAVERT in pre-approval clinical studies. One patient was rechallenged with SOMAVERT, and the recurrence of elevated transaminase levels suggested a probable causal relationship between administration of the drug and the elevation in liver enzymes. A liver biopsy performed on the second patient was consistent with chronic hepatitis of unknown etiology. In both patients, the transaminase elevations normalized after discontinuation of the drug. Elevations in ALT and AST levels were not associated with increased levels of TBIL and ALP, with the exception of two patients with minimal associated increases in ALP levels (i.e., less than 3 times ULN). The transaminase elevations did not appear to be related to the dose of SOMAVERT administered, generally occurred within 4 to 12 weeks of initiation of therapy, and were not associated with any identifiable biochemical, phenotypic, or genetic predictors.
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).
Overdosage
In one reported incident of acute overdose with SOMAVERT during pre-marketing clinical studies, a patient self-administered 80 mg/day (2.7 times the maximum recommended maintenance dosage) for seven days. The patient experienced a slight increase in fatigue, had no other complaints, and demonstrated no significant clinical laboratory abnormalities. In cases of overdose, administration of SOMAVERT should be discontinued and not resumed until IGF-1 levels return to within or above the normal range.