PEGVISOMANT
| PEGVISOMANT (peg-vis'o-mant) Somavert Classifications: hormone; growth hormone modifier; growth hormone receptor antagonist; Therapeutic: growth hormone receptor antagonist Pregnancy Category: B |
Availability
10 mg, 15 mg, 20 mg, powder for injection
Action
A growth hormone (GH) receptor antagonist that binds to GH receptors on cell surfaces where it blocks the binding of GH and interferes with its action and ability to stimulate production of insulin-like growth factor I (IGF-I).
Therapeutic Effect
Produces a significant decrease in the level of serum insulin-like growth factor I (IGF-I), the primary mediator of GH effects on body tissues.
Uses
Treatment of acromegaly when other treatments have failed or are inappropriate.
Contraindications
Hypersensitivity to pegvisomant; hypersensitivity to latex.
Cautious Use
Pituitary tumors; diabetes mellitus; hepatic and/or renal impairment; pregnancy (category B); lactation; children, elderly.
Route & Dosage
| Acromegaly Adult: SC 40 mg loading dose, then 10 mg once daily. Adjust dose in 5 mg increments, up to 30 mg/d, based on serum IGF-I concentrations. |
Administration
Subcutaneous- Allow vials to reach room temperature, then reconstitute by adding 1 mL of supplied diluent (sterile water for injection) to the vial. Direct diluent against the glass wall of vial, then mix by gently rolling between palms of hands to dissolve. DO NOT SHAKE. Solution should be clear and colorless. Use within 6 h of reconstitution.
- Inject SC and exercise caution not to inject IV.
- Rotate injection sites and do not use any site more than once every 1–2 mo.
- Store vials of powder at 2°–8° C (36°–46° F).
Adverse Effects (≥1%)
Body as a Whole: Asthenia, flu-like syndrome, infection, injection site reactions, back pain, paresthesias, peripheral edema. CNS: Dizziness. CV: Angina, chest pain, hypertension, MI. GI: Elevated liver function tests, diarrhea, nausea, vomiting. Metabolic: Hypercholesterolemia, hypoglycemia, and low titer nonneutralizing antigrowth hormone antibodies. Musculoskeletal: Arthralgia. Respiratory: Sinusitis.Diagnostic Test Interference
Similar to growth hormone and may cross-react with growth hormone assays. Do not use these assays to monitor pegvisomant therapy.
Interactions
Drug: opiate agonists may lead to higher pegvisomant dosing requirements; may need to decrease doses of insulin, oral antidiabetic agents.Pharmacokinetics
Absorption: 57% from SC injection site. Peak: 33–77 h. Half-Life: 6 d.Nursing Implications
Assessment & Drug Effects
- Montior CV status with baseline and periodic BP measurements.
- Monitor diabetics for loss of glycemic control.
- Withhold drug and notify physician for significant elevation in AST/ALT or S&S of hepatitis.
- Lab tests: IGF-I levels 4–6 wk after initiation of therapy or any dose adjustment, then q6mo after IGF-I levels have normalized; periodic LFTs and lipid profile; frequent blood glucose monitoring, especially if diabetic.
Patient & Family Education
- Report promptly any of the following: chest pain or tightness, signs of infection (e.g., fever, chills, flu-like symptoms).
- Discontinue drug and notify physician immediately if jaundice appears.
- Do not drive or engage in other hazardous activities until reaction to drug is known.
Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; 
Canadian drug name; 
Prototype drug