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(pegvisomant) for Injection
Pegvisomant is a protein of recombinant DNA origin containing 191 amino acid residues to which several polyethylene glycol (PEG) polymers are covalently bound (predominantly 4 to 6 PEG/protein molecule). The molecular weight of the protein of pegvisomant is 21,998 Daltons. The molecular weight of the PEG portion of pegvisomant is approximately 5000 Daltons. The predominant molecular weights of pegvisomant are thus approximately 42,000, 47,000, and 52,000 Daltons. The schematic shows the amino acid sequence of the pegvisomant protein (PEG polymers are shown attached to the 5 most probable attachment sites). Pegvisomant is synthesized by a specific strain of Escherichia coli bacteria that has been genetically modified by the addition of a plasmid that carries a gene for GH receptor antagonist. Biological potency is determined using a cell proliferation bioassay. Binding of Somavert to the GH receptor results in disruption of the proper binding of the second GH receptor with inhibition of functional receptor dimerization and subsequent intracellular signaling.
Stippled residues indicate PEG attachment sites (Phe 1, Lys38, Lys41, Lys70, Lys115, Lys120, Lys140, Lys145, Lys158)
Shown below are the amino acid substitutions in pegvisomant, relative to human GH.
|Ala 21||Asn 21|
|Lys 168||Ala 168|
|Glu 174||Ser 174|
|Ile 179||Thr 179|
SOMAVERT for injection is supplied as a sterile, white lyophilized powder intended for subcutaneous injection after reconstitution with 1 mL of Sterile Water for Injection. SOMAVERT is available in single-dose sterile vials containing 10, 15, or 20 mg of pegvisomant protein (approximately 10, 15, and 20 U activity, respectively). Each vial also contains 1.36 mg of glycine, 36.0 mg of mannitol, 1.04 mg of sodium phosphate dibasic anhydrous, and 0.36 mg of sodium phosphate monobasic monohydrate.
SOMAVERT is supplied in packages that include a vial containing diluent. Sterile Water for Injection, USP, is a sterile, nonpyrogenic preparation of water for injection that contains no bacteriostat, antimicrobial agent, or added buffer, and is supplied in single-dose containers to be used as a diluent.
What are the possible side effects of pegvisomant (Somavert)?
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; feeling like you might pass out; swelling of your face, lips, tongue, or throat.
Stop using pegvisomant and call your doctor at once if you have a serious side effect such as:
- nausea, upper stomach pain, loss of appetite;
- swelling, rapid weight gain; or
- itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).
Less serious side effects may include:
- cold symptoms such as stuffy...
What are the precautions when taking pegvisomant (Somavert)?
Before using this medication, tell your doctor or pharmacist if you are allergic to it or if you have any other allergies. This product may contain inactive ingredients (such as dry natural rubber/latex in the product packaging), which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver problems.
If you have diabetes, pegvisomant may help improve symptoms of diabetes, such as lowering high blood sugar levels. Check your blood sugar regularly. Your doctor may need to adjust your diabetes medications.
Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription...
Last reviewed on RxList: 12/19/2013
This monograph has been modified to include the generic and brand name in many instances.
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