Pegvisomant
FDA Drug Information • Also known as: Somavert
- Brand Names
- Somavert
- Dosage Form
- INJECTION, POWDER, LYOPHILIZED, FOR SOLUTION
- Product Type
- DRUG FOR FURTHER PROCESSING
Description
11 DESCRIPTION Pegvisomant is an analog of human growth hormone (GH) of recombinant DNA origin that acts as a GH receptor antagonist. It contains 191 amino acid residues. The molecular weight of pegvisomant is 22 kDa. The molecular weight of the PEG portion of pegvisomant is approximately 5 kDa. The predominant molecular weights of pegvisomant are thus approximately 42, 47, and 52 kDa. 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. Stippled residues indicate PEG attachment sites (Phe 1 , Lys 38 , Lys 41 , Lys 70 , Lys 115 , Lys 120 , Lys 140 , Lys 145 , Lys 158 ) Shown below are the amino acid substitutions in pegvisomant, relative to human GH. hGH Pegvisomant His 18 Asp 18 Ala 21 Asn 21 Gly 120 Lys 120 Arg 167 Asn 167 Lys 168 Ala 168 Asp 171 Ser 171 Lys 172 Arg 172 Glu 174 Ser 174 Ile 179 Thr 179 SOMAVERT (pegvisomant) for injection is a sterile, white lyophilized powder intended for subcutaneous injection after reconstitution. SOMAVERT is supplied in packages that include a single-dose prefilled syringe containing 1 mL of Sterile Water for Injection, USP, that is a sterile, nonpyrogenic preparation of water for injection that contains no bacteriostat, antimicrobial agent, or added buffer, to be used as a diluent. SOMAVERT is available in single-dose sterile vials containing 10 mg, 15 mg, 20 mg, 25 mg or 30 mg of pegvisomant. SOMAVERT 10 mg, 15 mg, and 20 mg vials also contain glycine (1.36 mg), mannitol (36 mg), sodium dihydrogen phosphate monohydrate (0.36 mg), and sodium phosphate dibasic anhydrous (1.04 mg). After reconstitution with 1 mL of Water for Injection, USP, the resulting concentration is 10 mg/mL, 15 mg/mL and 20 mg/mL, respectively, with a pH of 7.1 – 7.7. SOMAVERT...
What Is Pegvisomant Used For?
1 INDICATIONS AND USAGE SOMAVERT is indicated for the treatment of acromegaly in patients who have had an inadequate response to surgery or radiation therapy, or for whom these therapies are not appropriate. The goal of treatment is to normalize serum insulin-like growth factor-1 (IGF-1) levels. SOMAVERT is a growth hormone receptor antagonist indicated for the treatment of acromegaly in patients who have had an inadequate response to surgery or radiation therapy, or for whom these therapies are not appropriate. The goal of treatment is to normalize serum insulin-like growth factor-1 (IGF-1) levels. ( 1 )
Dosage and Administration
2 DOSAGE AND ADMINISTRATION
Administer a 40 mg loading dose subcutaneously under physician supervision. ( 2.1 ) After proper injection instruction, on day after loading dose, patients or caregivers begin daily subcutaneous injections of 10 mg. ( 2.1 ) Adjust dosage in 5 mg increments or decrements until serum IGF-1 concentrations are maintained within age-adjusted normal range. Do not adjust dosage based on growth hormone (GH) levels or signs or symptoms of acromegaly. ( 2.1 ) Dosage range is 10 mg to 30 mg once daily. ( 2.1 ) Perform liver tests prior to first dosage and if greater than 3 times upper limit of normal should work-up prior to SOMAVERT administration. ( 2.2 ) Follow reconstitution and injection procedures. ( 2.3 , 2.4 ) 2.1 Dosage Information The recommended loading dose of SOMAVERT is 40 mg given subcutaneously, under healthcare provider supervision. Provide proper training in subcutaneous injection technique to patients or their caregivers so they can receive once daily subcutaneous injections. On the next day following the loading dose, instruct patients or their caregivers to begin daily subcutaneous injections of 10 mg of SOMAVERT. Titrate the dosage to normalize serum IGF-1 concentrations (serum IGF-1 concentrations should be measured every four to six weeks). The dosage should not be based on growth hormone (GH) concentrations or signs and symptoms of acromegaly. It is unknown whether patients who remain symptomatic while achieving normalized IGF-1 concentrations would benefit from increased SOMAVERT dosage. Increase the dosage by 5 mg increments every 4–6 weeks if IGF-1 concentrations are elevated. Decrease the dosage by 5 mg decrements every 4–6 weeks if IGF-1 concentrations are below the normal range. IGF-1 levels should also be monitored when a SOMAVERT dose given in multiple injections is converted to a single daily injection [see Clinical Pharmacology (12) ] . The recommended dosage range is between 10 mg to 30 mg given subcutaneously once daily and the maximum daily dosage is 30 mg given subcutaneously once daily. 2.2 Assess Liver Tests Prior to Initiation of SOMAVERT Prior to the start of SOMAVERT, patients should have an assessment of baseline levels of liver tests [serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), serum total bilirubin (TBIL), and alkaline phosphatase (ALP)]. For recommendations regarding initiation of SOMAVERT based on baseline liver tests and recommendations for monitoring of liver tests while on SOMAVERT, refer to Table 1 in Warning and Precautions (5.2) . 2.3 Loading Dose Injection Procedure The following instructions are for the healthcare provider to reconstitute and prepare the 40 mg loading dose. The healthcare provider will need to reconstitute 2 vials of lyophilized powder of SOMAVERT each containing 20 mg of pegvisomant with supplied diluent [two vials of lyophilized powder and two syringes containing 1 mL of diluent (Sterile Water for Injection,...Side Effects (Adverse Reactions)
6 ADVERSE REACTIONS Clinically significant adverse reactions that appear in other section of the labeling include:
Hypoglycemia Associated with GH Lowering in Patients with Diabetes Mellitus [see Warnings and Precautions (5.1) ] Liver Toxicity [see Warnings and Precautions (5.2) ] Cross-Reactivity with GH Assays [see Warnings and Precautions (5.3) ] Lipohypertrophy [see Warnings and Precautions (5.4) ] Systemic Hypersensitivity [see Warnings and Precautions (5.5) ] Elevations of serum concentrations of ALT and AST greater than ten times the ULN were reported in two patients (0.8%) exposed to SOMAVERT in pre-approval clinical studies. One patient was rechallenged with SOMAVERT, and the recurrence of elevated transaminase levels suggested a probable causal relationship between administration of the drug and the elevation in liver enzymes. A liver biopsy performed on the second patient was consistent with chronic hepatitis of unknown etiology. In both patients, the transaminase elevations normalized after discontinuation of the drug. Elevations in ALT and AST levels were not associated with increased levels of TBIL and ALP, with the exception of two patients with minimal associated increases in ALP levels (i.e., less than 3 times ULN). The transaminase elevations did not appear to be related to the dose of SOMAVERT administered, generally occurred within 4 to 12 weeks of initiation of therapy, and were not associated with any identifiable biochemical, phenotypic, or genetic predictors. Most common reported adverse reactions (>6%) are infection, pain, nausea, diarrhea, abnormal liver tests, flu syndrome, injection site reaction. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Pfizer Inc. at 1-800-438-1985 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In a 12-week randomized, placebo-controlled, double-blind, fixed-dose study of SOMAVERT in subjects with acromegaly, 32 subjects received placebo and 80 subjects received SOMAVERT once daily [see Clinical Studies (14) ] . A total of 108 subjects (30 placebo, 78 SOMAVERT) completed 12 weeks of study treatment. Overall, eight patients with acromegaly (5.3%) withdrew from pre-marketing clinical studies because of adverse events, including two patients with marked transaminase elevations, one patient with lipohypertrophy at the injection sites, and one patient with substantial weight gain. Most adverse events did not appear to be dose-dependent. Table 3 shows the incidence of adverse events that were reported in at least two patients treated with SOMAVERT and at frequencies greater than placebo during the 12-week, placebo-controlled study. Table 3. Adverse Reactions in a 12-week Placebo-Controlled Study in Patients with Acromegaly Table includes only those events that were reported in at least 2 patients and at a higher incidence in patients treated with SOMAVERT than in patients treated with placebo. Placebo n=32 SOMAVERT 10 mg/day n=26 15 mg/day n=26 20 mg/day N=28 Infection The 6 events coded as "infection" in the group treated with SOMAVERT 10 mg were reported as cold symptoms (3), upper respiratory infection (1), blister (1), and ear infection (1). The 2 events in the placebo group were reported as cold symptoms (1) and chest infection (1). 2 (6%) 6 (23%) 0 0 Pain 2 (6%) 2 (8%) 1 (4%) 4 (14%) Nausea 1 (3%) 0 2 (8%) 4 (14%) Diarrhea 1 (3%) 1 (4%) 0 4 (14%) Abnormal liver function tests 1 (3%) 3 (12%) 1 (4%) 1 (4%) Flu syndrome 0 1 (4%) 3 (12%) 2 (7%) Injection site reaction 0 2 (8%) 1 (4%) 3 (11%) Dizziness 2 (6%) 2 (8%) 1 (4%) 1 (4%) Accidental injury 1 (3%) 2 (8%) 1 (4%) 0 Back pain 1 (3%) 2 (8%) 0 1 (4%) Sinusitis 1 (3%) 2 (8%) 0 1 (4%) Chest pain 0 1 (4%) 2 (8%) 0...Drug Interactions
7 DRUG INTERACTIONS
Insulin and/or Oral hypoglycemic Agents: Patients with acromegaly and with diabetes mellitus may require careful monitoring and dose reductions of insulin and/or oral hypoglycemic agents. ( 5.2 , 7.1 ) Opioids: Patients on opioids may need higher SOMAVERT doses to achieve appropriate IGF-1 suppression. ( 7.2 ) 7.1 Insulin and/or Oral Hypoglycemic Agents After initiation of SOMAVERT, patients with acromegaly and diabetes mellitus treated with insulin and/or oral hypoglycemic agents may require dose reductions of insulin and/or oral hypoglycemic agents [see Warnings and Precautions (5.1) ] . 7.2 Opioids In clinical studies, patients taking opioids often needed higher SOMAVERT doses to normalize IGF-1 concentrations compared with patients not receiving opioids. The mechanism of this interaction is not known.Contraindications
4 CONTRAINDICATIONS None. None. ( 4 )
Pregnancy and Breastfeeding
8.1 Pregnancy Risk Summary Postmarketing reports of SOMAVERT use in pregnant women are insufficient to establish a drug-associated risk for major birth defects, miscarriage or adverse maternal or fetal outcomes. Acromegaly may improve during pregnancy (see Clinical Considerations ) . In animal reproduction studies, fetotoxicity was observed at a dose that was 6 times the maximum recommended human dose based on body surface area following subcutaneous administration of pegvisomant during organogenesis or during the preimplantation period (see Data ) . The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2–4% and 15–20%, respectively. Clinical Considerations Disease-associated maternal and/or embryofetal risk Published data from case reports, case series, and a small interventional study in pregnant women with acromegaly have demonstrated that acromegaly may improve or stabilize without treatment during pregnancy, particularly if acromegaly is treated before pregnancy. In rare cases, acromegaly may worsen during pregnancy. Since IGF-1 levels may change physiologically during pregnancy and interpreting IGF-1 and growth hormone levels in pregnant women with acromegaly may be unreliable, clinical monitoring is recommended. Data Animal Data The effects of pegvisomant on early embryonic development and embryo-fetal development were evaluated in two separate studies, which were conducted in pregnant rabbits with pegvisomant at subcutaneous doses of 1, 3, and 10 mg/kg/day. There was no evidence of teratogenic effects associated with pegvisomant administration during organogenesis. At the 10-mg/kg/day dose (6 times the maximum human therapeutic dose based on body surface area), a reproducible, slight increase in post-implantation loss was observed in both studies.
Overdosage
10 OVERDOSAGE In one reported incident of acute overdose with SOMAVERT during pre-marketing clinical studies, a patient self-administered 80 mg/day (2.7 times the maximum recommended maintenance dosage) for seven days. The patient experienced a slight increase in fatigue, had no other complaints, and demonstrated no significant clinical laboratory abnormalities. In cases of overdose, administration of SOMAVERT should be discontinued and not resumed until IGF-1 levels return to within or above the normal range.
How Supplied
16 HOW SUPPLIED/STORAGE AND HANDLING SOMAVERT (pegvisomant) for injection is a white lyophilized powder supplied in the following strengths and package configurations: One Day Package Configuration Strength NDC Description 10 mg per vial 0009-7166-01 One single-dose vial with one prefilled syringe containing 1 mL of diluent (Sterile Water for Injection, USP) and a separate 27 -gauge ½ inch safety needle per carton 15 mg per vial 0009-7168-01 20 mg per vial 0009-7188-01 25 mg per vial 0009-7199-01 30 mg per vial 0009-7200-01 30-Day Package Configuration Strength NDC Description 10 mg per vial 0009-7166-30 Each outer carton contains three intermediate cartons, 30 prefilled syringes containing 1 mL of diluent (Sterile Water for Injection, USP), and 30 separate 27-gauge ½ inch safety needles. Each intermediate carton contains ten single-dose vials of Somavert. 15 mg per vial 0009-7168-30 20 mg per vial 0009-7188-30 25 mg per vial 0009-7199-30 30 mg per vial 0009-7200-30 Storage Prior to reconstitution:
The One Day Package of SOMAVERT should be stored in a refrigerator at 2°C to 8°C (36°F to 46°F). For the 30-Day Package, remove the three intermediate cartons containing the SOMAVERT vials and store in a refrigerator at 2°C to 8°C (36°F to 46°F). For convenience, the One Day Package and intermediate cartons in the 30-Day Package containing the SOMAVERT vial(s), may be stored at room temperature up to 25°C (77°F) for a single period of up to 30 days. o In the space provided on the carton, record the date when the carton was removed from the refrigerator and the discard date (30 days after removal from the refrigerator). o Once the carton has been stored at room temperature, it should not be placed back into the refrigerator. If not used within 30 days at room temperature, the vial(s) should be discarded. Discard the SOMAVERT vial(s) after the expiration date printed on the carton or the discard date, whichever is sooner. The prefilled syringe(s) may be stored at a...About This Information
This drug information is sourced from FDA-approved labeling via the openFDA database. It is intended for educational and reference purposes only. This is not medical advice. Always consult your healthcare provider before making decisions about medication. Drug information may be updated by the FDA; check with your pharmacist for the most current information.
What are side effects?
Side effects are unwanted reactions that can occur when taking a medication. They range from mild (headache, nausea) to severe (allergic reactions, organ damage). Not everyone experiences side effects, and severity varies. Report any concerning side effects to your doctor.
What are drug interactions?
Drug interactions occur when a medication is affected by another drug, food, or supplement. Interactions can make medications less effective or cause dangerous side effects. Always tell your doctor about all medications and supplements you take.