Somavert (pegvisomant)
An approved treatment for Acromegaly.
The same compound appears under different names depending on the context. Here is how to identify Pegvisomant wherever you encounter it, plus the key facts at a glance.
- Generic name
- Pegvisomant
- Brand name
- Somavert
- Development code
- B2036-PEG
- Drug class
- Growth hormone receptor antagonist
- Manufacturer
- Pfizer
- How it's taken
- Treatment starts with a 40 mg loading dose given under a healthcare provider's supervision.
A unique drug that blocks growth hormone receptors rather than suppressing hormone production. Given as a daily injection, it normalizes IGF-1 levels even when GH remains elevated.
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Where Pegvisomant fits
Approved for acromegaly when surgery or radiation has not worked well enough or is not appropriate. The label does not require trying somatostatin analogs first, though in practice pegvisomant is often used when they are not enough, either alone or added to them. The only GH receptor antagonist, directly blocking growth hormone action rather than reducing its secretion.
How Pegvisomant works
Pegvisomant works differently from other acromegaly medicines. Instead of stopping growth hormone production, it blocks growth hormone's effects on the body. It binds to growth hormone receptors on cells and prevents growth hormone from attaching and causing problems, like blocking a doorway so growth hormone can't enter.
Mechanism: Growth hormone receptor antagonist that blocks GH from binding its receptor, preventing formation of the active signaling complex
Side effects and safety
Common side effects include infections such as colds, pain, nausea, diarrhea, abnormal liver tests, flu-like symptoms, and injection site reactions. Your liver enzymes may increase, so regular blood tests are needed. Tell your doctor about unusual tiredness, yellowing of skin or eyes, dark urine, or abdominal pain. If you have diabetes, Somavert can lower your blood sugar, so blood sugar is checked and your diabetes medicine may need to be reduced. Allergic reactions throughout the body (systemic hypersensitivity) have been reported, so get medical help right away if you think you are having a serious allergic reaction. The label also warns about a build-up of fatty tissue under the skin at injection sites (lipohypertrophy), and that Somavert can interfere with some growth hormone blood tests.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Pegvisomant
Treatment starts with a 40 mg loading dose given under a healthcare provider's supervision. From the next day, you or a caregiver give a 10 mg injection under the skin once a day at home after training, and the dose is raised or lowered by 5 mg every 4 to 6 weeks based on IGF-1, within a range of 10 to 30 mg a day. Regular blood tests are needed to check IGF-1 levels and liver function. Insurance may require prior authorization.
Availability and cost
Only available as the brand-name product.
Unique growth hormone receptor antagonist produced through recombinant DNA technology with PEGylation for extended half-life. The only drug in its class for acromegaly.
Help paying for Somavert
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
SOMAVERT Copay Card: eligible commercially insured patients may pay as little as $5 per prescription fill; annual savings up to $20,000. Offer expires 12/31/2026.
For: private insurance · source - Free medicine program
Pfizer Patient Assistance Program may provide SOMAVERT at no cost to qualified uninsured or government-insured patients.
For: no insurance, Medicare, Medicaid, TRICARE · source - Insurance and case manager help
Pfizer Bridge Program offers personalized treatment support, a patient hotline and one-on-one injection training.
The official page does not say who qualifies. Ask the program. · source
Good to know: Copay card excludes Medicare, Medicaid, TRICARE, VA and other government programs. Free medicine is through the Pfizer Patient Assistance Foundation, a separate entity.
- From a charity · TotalAssist (formerly PAN Foundation)Acromegaly fundOpen
Pays for: Out-of-pocket costs for approved medications, up to $5,000 per year. Requires Medicare, Medicaid or TRICARE.
- From a charity · The Assistance FundAcromegaly fundWaitlist
Pays for: Copays, coinsurance, deductibles and other health-related expenses.
The foundation says: “WAITLIST — Accepting Waitlist Patients. TAF is currently accepting requests to join the enrollment waitlist for this program. Waitlists a…”
How acromegaly treatments compare
Five FDA-approved medications are available for acromegaly. Your endocrinologist will recommend a treatment based on your tumor size, IGF-1 levels, symptoms, and how you respond to initial therapy. This chart summarizes the key practical differences between options.
5 FDA-approved acromegaly treatments are available: Sandostatin LAR (octreotide, approved 1998); Somatuline Depot (lanreotide, approved 2007); Signifor LAR (pasireotide, approved 2014); Somavert (pegvisomant, approved 2003); Palsonify (paltusotine, approved 2025). Sandostatin LAR is typically used as first-line medical therapy (injectable).
| Drug | How it works | How it’s given | How often | Where you get it | Typical use | FDA approved |
|---|---|---|---|---|---|---|
Sandostatin LAR octreotide | Somatostatin analog — mimics a hormone that tells the pituitary to release less growth hormone | Intramuscular injection (gluteal muscle) | Every 4 weeks | Clinic or infusion center | First-line medical therapy (injectable) | 1998 |
Somatuline Depot lanreotide | Somatostatin analog — same receptor target as octreotide, but given as a deep subcutaneous gel rather than an intramuscular injection | Deep subcutaneous injection (upper outer buttock) | Every 4 weeks (FDA-approved extended dosing: 120mg every 6–8 weeks for biochemically controlled patients) | Clinic (healthcare provider administration per FDA label) | First-line medical therapy (injectable) | 2007 |
Signifor LAR pasireotide | Multi-receptor somatostatin analog — targets more receptor subtypes than first-generation options | Intramuscular injection (gluteal muscle) | Every 4 weeks | Clinic or infusion center | Second-line, after first-generation somatostatin analogs | 2014 |
Somavert pegvisomant You are here | Growth hormone receptor antagonist — blocks GH from binding to cells instead of reducing GH release | Subcutaneous injection (self-administered) | Daily | Home (self-injection) | Second-line or add-on to somatostatin analog | 2003 |
Palsonify paltusotine | Oral somatostatin agonist — activates the same SST2 receptor as injectable somatostatin analogs, taken as a pill | Oral tablet | Once daily | Home (oral, no injection needed) | First-line medical therapy, or switch from injectable somatostatin analog | 2025 |
This chart summarizes approved acromegaly treatments to help you understand the landscape. It is not medical advice. Treatment decisions depend on your individual health profile, tumor characteristics, lab results, and response to therapy. Dosing intervals shown reflect FDA labeling; your endocrinologist may adjust intervals based on your individual response. Always discuss options with your endocrinologist.
Clinical trial results
FDA approved Somavert in March 2003. In the 12-week placebo-controlled trial of 112 people, IGF-1 fell by an average of 27%, 48% and 63% on 10, 15 and 20 mg a day, compared with 4% on placebo. In the open-label extension, 100 of 108 people (93%) had a normal IGF-1 at some visit. It's particularly useful for patients who don't respond to or can't tolerate somatostatin analogues.
Development history
Pegvisomant was discovered at Ohio University in 1987 and developed through multiple clinical trials before FDA approval in 2003. Pfizer commercialized it as Somavert. It represented a revolutionary new approach by blocking growth hormone effects rather than production.
Explore Acromegaly trials
Other Acromegaly treatments
Common questions about Pegvisomant
▸What is Pegvisomant (Somavert)?
A unique drug that blocks growth hormone receptors rather than suppressing hormone production. Given as a daily injection, it normalizes IGF-1 levels even when GH remains elevated.
▸How does Pegvisomant work?
Pegvisomant works differently from other acromegaly medicines. Instead of stopping growth hormone production, it blocks growth hormone's effects on the body. It binds to growth hormone receptors on cells and prevents growth hormone from attaching and causing problems, like blocking a doorway so growth hormone can't enter.
▸What are the side effects of Pegvisomant?
Common side effects include infections such as colds, pain, nausea, diarrhea, abnormal liver tests, flu-like symptoms, and injection site reactions. Your liver enzymes may increase, so regular blood tests are needed. Tell your doctor about unusual tiredness, yellowing of skin or eyes, dark urine, or abdominal pain. If you have diabetes, Somavert can lower your blood sugar, so blood sugar is checked and your diabetes medicine may need to be reduced. Allergic reactions throughout the body (systemic hypersensitivity) have been reported, so get medical help right away if you think you are having a serious allergic reaction. The label also warns about a build-up of fatty tissue under the skin at injection sites (lipohypertrophy), and that Somavert can interfere with some growth hormone blood tests.
▸How is Pegvisomant taken?
Treatment starts with a 40 mg loading dose given under a healthcare provider's supervision. From the next day, you or a caregiver give a 10 mg injection under the skin once a day at home after training, and the dose is raised or lowered by 5 mg every 4 to 6 weeks based on IGF-1, within a range of 10 to 30 mg a day. Regular blood tests are needed to check IGF-1 levels and liver function. Insurance may require prior authorization.
▸Is Pegvisomant FDA approved?
Yes, Pegvisomant (Somavert) is FDA approved (2003) for the treatment of Acromegaly.
▸How does pegvisomant work differently from somatostatin analogs?
Somatostatin analogs reduce growth hormone production at the pituitary, while pegvisomant blocks GH from binding to its receptor at the tissue level. This means pegvisomant normalizes IGF-1 levels even if GH levels remain elevated, making it effective when somatostatin analogs fail.
▸Why is liver monitoring required with pegvisomant?
Pegvisomant can cause liver enzyme elevations, so liver function tests are required before starting treatment and periodically during therapy. If liver enzymes reach 3 to 5 times the upper limit of normal, tests are repeated weekly. Somavert is stopped right away at 5 times the limit or higher, or at 3 times the limit with any rise in bilirubin.
▸Is pegvisomant used alone or in combination?
The FDA label covers Somavert used on its own and does not describe combining it with other drugs. Adding it to a somatostatin analog when neither alone controls IGF-1 is an off-label use to discuss with your doctor.
▸How is Somavert administered?
Treatment starts with a 40 mg loading dose given under a healthcare provider's supervision. From the next day, you or a caregiver give a 10 mg injection under the skin once a day at home after training, and the dose is raised or lowered by 5 mg every 4 to 6 weeks based on IGF-1, within a range of 10 to 30 mg a day.
▸Was pegvisomant the first GH receptor antagonist?
Yes. Pegvisomant (Somavert) was approved in 2003 as the first and only growth hormone receptor antagonist. It represented a novel approach to acromegaly treatment by blocking GH action rather than reducing GH production.
▸What patient support does Pfizer offer?
The Pfizer Bridge Program provides savings and support for Somavert patients, including copay assistance and other financial resources.