Somavert

Somavert,

a trademark for pegvisomant.

---

pegvisomant

Somavert

Pharmacologic class: Growth hormone (GH) receptor antagonist

Therapeutic class: GH analog

Pregnancy risk category B

Action

Selectively binds to GH receptors on cell surfaces, where it blocks binding of endogenous GH and interferes with GH signal transduction. This action decreases blood levels of insulin-like growth factor-1 (IGF-1) and other GH-responsive serum proteins.

Availability

Solution: 10-mg, 15-mg, and 20-mg vials

⊘Indications and dosages

➣ Acromegaly

Adults: Initial subcutaneous loading dose of 40 mg, followed by 10 mg/day subcutaneously. May adjust in 5-mg increments after serum IGF-1 measurement q 4 to 6 weeks; don't exceed maximum daily maintenance dosage of 30 mg.

Contraindications

• Hypersensitivity to drug, its components, or latex (in vial stopper)

Precautions

Use cautiously in:
• GH-excreting tumors, diabetes mellitus, hepatic dysfunction
• pregnant or breastfeeding patients
• children.

Administration

• Reconstitute in vial with 1 ml of sterile water for injection.
• Roll vial gently between palms to mix; don't shake. Withdraw prescribed dosage and administer subcutaneously.

Route	Onset	Peak	Duration
Subcut.	Unknown	Unknown	24 hr

Adverse reactions

CNS: dizziness, paresthesia

CV: chest pain, hypertension, peripheral edema

EENT: sinusitis

GI: nausea, diarrhea, abdominal pain

Musculoskeletal: back pain

Other: infection, pain, injection site reaction, accidental injury, flulike symptoms

Interactions

Drug-drug. Insulin, oral hypoglycemics: decreased insulin sensitivity, reduced requirements for these drugs

Opioids: increased pegvisomant requirement

Drug-diagnostic tests. GH assays: interference with GH measurement

Liver function tests: abnormal results

Drug-behaviors. Opioid addiction: increased pegvisomant requirement

Patient monitoring

• Assess liver function tests; watch for signs and symptoms of hepatic dysfunction.
• Monitor serum IGF-1 level. If appropriate, discuss dosage adjustments with prescriber.
• Monitor vital signs; check for hypertension, chest pain, and peripheral edema.
• Measure temperature. Watch for signs and symptoms of infection, especially sinusitis or flulike symptoms.
• Assess blood glucose level closely in diabetic patient. Notify prescriber of significant decrease.

Patient teaching

• Teach patient proper technique for reconstituting and administering drug subcutaneously.
☞ Instruct patient to immediately report chest pain, peripheral edema, or signs or symptoms of infection.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects him.
• Teach diabetic patient to monitor blood glucose level closely and report significant decrease.
☞ Instruct patient to report yellowing of skin or eyes and other signs and symptoms of hepatic dysfunction. Tell him he'll undergo frequent liver function tests.
• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs, tests, and behaviors mentioned above.