General

Pronunciation:
peg-vis-o-mant

Trade Name(s)

• Somavert

Ther. Class.

hormones

Pharm. Class.

growth hormones

Indications

Treatment of acromegaly in patients who do not respond to or are not candidates for surgery, radiation, or other medical therapies.

Action

• Binds to growth hormone (GH) receptor sites on cell surfaces, blocking the effects of endogenous growth hormone.
• Bound to polyethylene glycol (PEG) to reduce clearance and increase duration of action.

Therapeutic Effect(s):

Decreased manifestations of acromegaly and normalized insulin-like growth factor-1 (IGF-1) levels.

Pharmacokinetics

Absorption: 57% absorbed following SUBQ administration.

Distribution: Does not distribute extensively into tissues.

Metabolism and Excretion: Unknown.

Half-life: 6 days.

TIME/ACTION PROFILE (effects on IGF-1)

Contraindication/Precautions

Contraindicated in:

• Hypersensitivity
• Latex allergy (vial stopper contains latex).

Use Cautiously in:

• Diabetes mellitus
• Patients with growth hormone-secreting tumors
• OB:   Safety not established in pregnancy
• Lactation:  Use while breastfeeding only if potential maternal benefit justifies potential risk to infant
• Pedi:   Safety and effectiveness not established in children.

Adverse Reactions/Side Effects

CV: hypertension, peripheral edema

Derm: lipohypertrophy

Endo: ↑ glucose tolerance, growth hormone deficiency

GI: ↑ liver enzymes

GU: ↑ fertility

MS: back pain

Misc: hypersensitivity reactions (including anaphylaxis and angioedema)

* CAPITALS indicate life-threatening.
Underline indicate most frequent.

Interactions

Drug-Drug

Patients receiving  opioid analgesics  often require ↑ doses of pegvisomant to normalize IGF-1.

Route/Dosage

SUBQ (Adults): Loading dose: 40 mg;  maintenance dose: 10 mg daily, further adjustments in increments/decrements of 5 mg are made based on monitoring of IGF-1 levels (not to exceed 30 mg/day).

Availability

Lyophilized powder for injection: 10 mg/vial, 15 mg/vial, 20 mg/vial, 25 mg/vial, 30 mg/vial

Assessment

• Assess patient for signs and symptoms of acromegaly (ring size, soft-tissue swelling, arthralgia, headache, perspiration, fatigue) periodically during therapy.
• Monitor patient for signs and symptoms or hepatitis or other liver injury (jaundice, hyperbilirubinemia, fatigue, nausea, vomiting, right upper quadrant pain, ascites, unexplained edema, easy bruising). If these occur, immediately perform a comprehensive hepatic work-up; may require discontinuation.
• Monitor for signs and symptoms of systemic hypersensitivity reactions (anaphylactic reactions, laryngospasm, angioedema, generalized skin reactions, rash, erythema, pruritus, urticaria) during therapy. Symptoms may not occur after re-challenge.

Lab Test Considerations:

Monitor serum IGF-1 levels 4–6 wk after therapy is initiated or any dose adjustments are made and at least every 6 mo after IGF-1 levels have normalized. Levels should be maintained within the age-adjusted normal range.

• Monitor serum glucose carefully in patients with insulin-dependent diabetes; may increase glucose tolerance causing hypoglycemia, requiring decrease in dose of antidiabetic medications.
• Measure liver tests (serum ALT, AST, total bilirubin and alkaline phosphatase levels) at baseline.  If normal: Monitor liver tests monthly during first 6 mo of treatment, quarterly for next 6 mo, and biannually for the next year.  If liver tests are elevated, but ≤3 times the upper limit of normal: Monitor liver tests monthly for at least 1 year after initiation of therapy and biannually for the next year.  If >3 times the upper limit of normal: Do not treat with pegvisomant until a comprehensive work-up establishes the cause of liver dysfunction. If pegvisomant is used, monitor liver tests very closely.
• If patient develops liver test elevations or other signs or symptoms of liver dysfunction during therapy, monitor as follows:  If ≥3 but <5 times the upper limit of normal, without signs or symptoms of hepatitis or other liver injury, or ↑ in serum total bilirubin: May continue therapy, but monitor liver tests weekly and perform a comprehensive work-up to determine if alternative cause of liver dysfunction is present.  If liver tests are >5 times the upper limit of normal or AST and ALT are >3 times the upper limit of normal associated with any ↑ in total bilirubin: Discontinue pegvisomant immediately, perform a comprehensive work-up, including serial liver tests. If liver tests normalize, therapy may be cautiously reinstated with frequent monitoring of liver tests.
• Do not use serum GH levels to adjust dose. Pegvisomant interferes with the measurement of serum GH concentrations by commercially available assays and may cause an increase in levels.

Implementation

• Administer loading dose under supervision of health care professional.
• To reconstitute, withdraw 1 mL of sterile water from diluent provided and inject into vial aiming stream at sides of vial. Gently roll vial between hands to dissolve powder. Do not shake; may cause denaturation of medication. Discard vial containing remaining diluent. After reconstitution each vial contains 10, 15, 20, 25, or 30 mg of pegvisomant/mL. Solution should be clear; do not administer solutions that are discolored, cloudy or contain a participate. Administer only 1 dose/vial. Store in refrigerator prior to reconstitution; let warm to room temperature for 10 min prior to administration. Reconstituted solution is stable for 6 hr at room temperature; administer within 6 hr of reconstitution.
• SUBQ Administer with a 27- or 30-gauge needle at a 90° angle in the upper arm, upper thigh, abdomen, or buttocks. Rotate sites each day; do not inject into an area that has a rash, broken skin, or is bruised or lumpy. Do not massage area following injection.

Patient/Family Teaching

• Instruct patient on the correct technique for administering pegvisomant. Review patient information sheet, preparation of dose, administration sites and technique, and disposal of equipment into a puncture-resistant container. Inform patient that further questions may be answered by their health care professional or by calling (800)-645-1280.
• Instruct patient that missed doses should be omitted; return to schedule the next day. Do not inject a double dose to make up for a forgotten injection.
• Instruct patient to inform their health care professional if they have diabetes or liver problems, or if they take opioid medications.
• May cause dizziness. Caution patient to avoid driving or other activities requiring alertness until effect of the drug is known.
• Advise patient to consult health care professional before taking other Rx or OTC medications, or herbal products.
• Instruct patient to notify health care professional promptly if skin or whites of the eyes turn yellow (jaundice), urine turn dark, stools turn light in color, decreased appetite, nausea, unexplained tiredness, or abdominal pain occur.
• Advise patient to notify health care professional if pregnancy is planned or suspected or if breastfeeding.
• Emphasize the need for frequent lab test to adjust dose and monitor for adverse effects.

Evaluation/Desired Outcomes

Maintenance of serum IGF-1 concentration within the age-adjusted normal range.

• Control of the signs and symptoms of acromegaly.