Somavert

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.

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, lipohypertrophy

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.

pegvisomant

(peg-vis-o-mant) ,

Somavert

(trade name)

Classification

Therapeutic: hormones
Pharmacologic: growth hormones
Pregnancy Category: B

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 effects

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

Pharmacokinetics

Absorption: 57% absorbed following subcut administration.
Distribution: Does not distribute extensively into tissues.
Metabolism and Excretion: Unknown.
Half-life: 6 days.

Time/action profile (effects on IGF-1)

ROUTEONSETPEAKDURATION
Subcutwithin 2 wk4–6 wkunknown

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Latex allergy (vial stopper contains latex).
Use Cautiously in: Diabetes mellitus; Patients with growth hormone-secreting tumors; Lactation / Pediatric: Safety not established; Obstetric: Use only if clearly needed.

Adverse Reactions/Side Effects

Cardiovascular

  • hypertension
  • peripheral edema

Gastrointestinal

  • ↑ LFTs

Musculoskeletal

  • back pain

Endocrinologic

  • growth hormone deficiency
  • ↑ glucose tolerance

Dermatologic

  • lipohypertrophy

Interactions

Drug-Drug interaction

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

Route/Dosage

Subcutaneous (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 reconstitution: 10-, 15-, and 20-mg vials with diluent (sterile water for injection)

Nursing implications

Nursing 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, bilirubinemia, 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.
  • 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 workup 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.

Potential Nursing Diagnoses

Delayed growth and development (Indications)

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, or 20 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.
  • Subcutaneous: 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.

Somavert

a trademark for pegvisomant.

Somavert

Brand name for PEGVISOMANT.
Mentioned in ?
References in periodicals archive ?
FDA--Approved Pegylated Therapeutics Commercial Name Drug Name Native Compound PegIntron Peginterferon Interferon alpha-2b alpha-2b Pegasys Peginterferon Interferon alpha-2a alfa-2a Adagen Pegadamase Adenosine deaminase Oncaspar Pegaspargase Asparaginase Krystexxa Pegloticase Mammalian urate oxidase Neulasta Pegfilgrastim Granulocyte colony-stimulating factor Cimzia Certolizumab Therapeutic pegol monoclonal antibody Mircera Polyethylene Epoetin beta glycol-epoetin beta Somavert Pegvisomant Growth hormone receptor antagonist Half- Half- life of life of Native Pegylated Commercial Clinical Compound Compound Name Indication (hours) (hours) PegIntron Hepatitis C, gliomas 9 28 Pegasys Hepatitis C 8 65 Adagen Severe combined 0.
Others may be less well-known but equally valuable: Remicade, a therapy for rheumatoid arthritis (NYU), Gardasil, the cervical cancer vaccine (multiple inventors), Somavert, for the treatment of acromegaly (Ohio University), Vorinostat, for T-cell lymphoma, Latanoprost, for glaucoma, and Palivizumab, for respiratory syncytial virus (all Columbia University).
Prior to 2010, Pfizer Health AB produced its legacy products Genotropin [R] and Somavert [R] in separate facilities.
The Bridge Program: Genotropin and Somavert support
Treatment with Somavert normalized IGF-I levels in up to 92% of patients treated for a mean of 1 year in one study, and up to 82% of patients in a 12-week study Compared with those on placebo, treatment was associated with improvements in signs and symptoms of the condition, such as ring size, soft tissue swelling, arthralgia, headache, perspiration, and fatigue.
SOMAVERT is marketed today by Pfizer in both the United States and Europe.
That market is currently dominated by once-a-month Sandostatin LAR(R) Depot (octreotide acetate for injectable suspension) from Novartis (NYSE: NVS) and includes daily injections of Somavert (pegvisomant for injection), a growth hormone receptor antagonist, from Pfizer (NYSE: PFE).
Somavert is a new therapeutic recombinant protein for treating certain growth hormone disorders in patients who respond inadequately to other treatments.
A26) Sales of Somavert totaled $7 million in the second quarter of 2004
On March 27, 2003, Nektar reported that SOMAVERT, which uses Nektar's PEGylation technology, was approved by the Food and Drug Administration (FDA) for the treatment of certain patients with acromegaly, a debilitating disease caused by a noncancerous tumor on the pituitary gland that produces increased quantities of growth hormone.
SOMAVERT is the fifth product using Nektar technology that has been approved in the United States.