Is pegvisomant FDA-approved, and what does the research show?

What is pegvisomant?

Pegvisomant is a growth hormone receptor antagonist: it sits on the receptor that growth hormone uses and blocks the hormone's signal ¹. The label describes it as "an analog of human growth hormone (GH) of recombinant DNA origin that acts as a GH receptor antagonist" ¹. An analog is an altered copy of a natural molecule. Recombinant means that genetically modified bacteria make it ¹.

The protein has 191 amino acids, the building blocks of proteins ¹. Chains of polyethylene glycol (PEG), a polymer, are attached to it "in order to reduce the clearance rate," the speed at which the body removes it ¹. It is sold under the brand name Somavert ¹.

Pegvisomant is "an analog of human growth hormone," made to block the hormone's receptor ¹. It is approved for acromegaly, which the label's patient leaflet describes as having "too much growth hormone" ¹. It is not a wellness, weight-loss or performance peptide, and the label names no such use ¹.

Is pegvisomant FDA-approved?

Yes, as a prescription drug for one condition. Drugs@FDA records the approval of Somavert (pegvisomant) on March 25, 2003 ². The record lists the drug under BLA 021106, an NDA until FDA deemed it a biologics license on March 23, 2020 ². Its products carry marketing status "Prescription" as of November 9, 2026, the date of the record's data ².

The label says 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" ¹. It adds that "the goal of treatment is to normalize serum insulin-like growth factor-1 (IGF-1) levels" ¹. IGF-1 is a blood protein whose level falls when growth hormone's action is blocked ¹.

The label refers to "GH-secreting tumors" in people with acromegaly ¹. It calls for blood tests of IGF-1 and of the liver before and during treatment ¹.

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How does pegvisomant work?

The FDA-approved label says pegvisomant "selectively binds to growth hormone (GH) receptors on cell surfaces, where it blocks the binding of endogenous GH, and thus interferes with GH signal transduction" ¹. Endogenous means the body's own. Signal transduction is the chain of messages a hormone sets off inside a cell.

With that signal blocked, IGF-1 in the blood falls, along with other proteins that respond to growth hormone ¹. The label says the drug did not cross-react with 19 other receptors tested ¹.

Pegvisomant does not lower growth hormone itself. In the main trial, growth hormone in the blood rose within two weeks of starting treatment, but the drug blocks that hormone at its receptors ¹. The label calls the rise "presumably the result of diminished inhibition of GH secretion as IGF-1 levels fall" ¹. IGF-1 fell in the same trial ¹.

Commercial growth hormone tests also detect the drug itself, so measured levels "will appear falsely elevated" ¹. The label says, "The dosage should not be based on growth hormone (GH) concentrations or signs and symptoms of acromegaly" ¹.

After an injection under the skin, the drug generally reaches its peak in the blood only after 33 to 77 hours ¹. Mean estimates of its half-life, the time for half the drug to leave the blood, ranged from 60 to 138 hours ¹.

What does the research show?

The label's clinical studies section rests on one placebo-controlled trial, with an extension in which every patient received the drug ¹. Two later papers add a longer follow-up and a comparison with another acromegaly drug ⁴, ⁵.

Approved by FDA for acromegaly: the trial enrolled 112 patients with acromegaly, 63 men and 49 women, for 12 weeks, and was published in April 2000 ³, ¹. It was randomized and double-blind. Patients were assigned by chance to placebo, a dummy injection, or to one of three daily doses, and neither they nor their doctors knew which ³, ¹. To enter, a patient's IGF-1 had to be at least 1.3 times the upper limit of normal for age ¹. Ninety-three had had surgery on the pituitary, the gland that makes growth hormone, and 57 of those had also had radiation ¹.

The main measure was the percent change in IGF-1 after 12 weeks ¹. By the label's analysis, mean IGF-1 fell 4 percent in the 31 placebo patients analyzed ¹. It fell 27, 48 and 63 percent in the lowest, middle and highest dose groups, of 26, 26 and 28 patients ¹. The published paper gives 26.7, 50.1 and 62.5 percent for those three groups ³. IGF-1 became normal in 10 percent of the placebo group and in 54, 81 and 89 percent of the three dose groups ³.

The trial also scored five signs and symptoms, each from 0 to 8: soft-tissue swelling, joint pain, headache, sweating and fatigue ¹. From a mean starting total of 15.2, the score rose by 1.3 with placebo and fell by 2.5, 4.4 and 4.7 in the three dose groups ¹. The paper reports statistically significant decreases, ones unlikely to be due to chance, in ring size, soft-tissue swelling, sweating and fatigue in the two higher dose groups ³. Its authors called these "preliminary results" ³.

In the extension, which was open-label, meaning everyone knew the drug was given, 109 patients were treated for a mean of 42.6 weeks ¹. Of the 108 with IGF-1 data, 100 (92.6 percent) had a normal IGF-1 "at any visit during the study" ¹.

Studied in people over a longer period: a report published in November 2001 covered 160 patients with acromegaly treated for an average of 425 days ⁴. The paper pooled the patients of the drug's development studies and calls its data "uncontrolled" ⁴. Of the patients treated for 12 months or more, 87 of 90 (97 percent) reached a normal IGF-1 ⁴. Mean pituitary tumor volume, measured by MRI, a type of body scan, in 131 patients over a mean of 11.46 months, did not change significantly ⁴. Two patients had "progressive growth of their pituitary tumours" ⁴.

Studied in people against another drug: a 52-week randomized trial, published online in December 2009, compared pegvisomant with long-acting octreotide, another acromegaly drug ⁵. It was open-label, ran at several centers, and compared the two in patients with acromegaly who had had neither radiation nor drug treatment ⁵. Fifty-six received pegvisomant and 57 received octreotide ⁵.

IGF-1 became normal in 51 percent of the pegvisomant group and 34 percent of the octreotide group ⁵. That difference was not statistically significant (p=0.09; the usual bar is below 0.05), so the trial did not show either drug to be better on this measure ⁵. Mean fasting glucose fell in the pegvisomant group and rose in the octreotide group, each a change within its own group ⁵. The change in tumor volume was similar between the groups ⁵.

The label reports no body weight by treatment group ¹. It lists "substantial weight gain" as the reason one patient with acromegaly withdrew from the studies run before approval ¹. It also lists weight gain among the four adverse events that ended treatment in the open-label extension ¹.

Every trial described enrolled patients with acromegaly, and none studied pegvisomant for weight, muscle, aging or performance ³, ¹, ⁴, ⁵. The label says safety and effectiveness in children "have not been established" ¹. It was not studied in patients with kidney impairment, and its trials included too few patients aged 65 and over to judge them separately ¹.

What are the side effects?

The label's comparison with placebo comes from the 12-week trial: 32 patients on placebo and 80 on pegvisomant, in dose groups of 26, 26 and 28 ¹. Injection site reactions were reported by none on placebo and by 2, 1 and 3 patients in the lowest, middle and highest dose groups ¹. Abnormal liver tests were reported in 1 patient on placebo and in 3, 1 and 1 ¹.

Nausea was reported by 1 on placebo and by 0, 2 and 4; diarrhea by 1 on placebo and by 1, 0 and 4 ¹. Events coded as infection, cold symptoms among them, were reported by 2 on placebo and by 6, 0 and 0 ¹. The label says most adverse events "did not appear to be dose-dependent" ¹. The paper says the incidence of adverse effects "was similar in all groups" ³.

Across the studies run before approval, eight patients with acromegaly (5.3 percent) withdrew because of adverse events ¹. Two had marked rises in transaminases, the liver enzymes measured in blood tests ¹. One had lipohypertrophy, a thickening of fat under the skin at the injection sites ¹. In the open-label extension, 93 of 109 patients (85.3 percent) had an adverse event, and 16 (14.7 percent) had a serious one ¹.

One label warning concerns the liver, and it calls for liver tests before treatment starts and at set intervals afterward ¹. In two open-label trials of 147 patients, it reports "asymptomatic, transient elevations in transaminases up to 15 times ULN" in fewer than 2 percent ¹. ULN is the upper limit of normal. Reports after approval describe rises to more than 20 times that limit together with raised bilirubin, another liver test ¹. "In many of these cases," the label says, stopping the drug "resulted in improvement or resolution of hepatic laboratory abnormalities" ¹.

Another warning is for people with diabetes. Growth hormone opposes insulin, so blocking it may improve glucose tolerance, the body's handling of sugar ¹. The label says such patients "should be carefully monitored" and their diabetes drugs reduced as necessary "to avoid hypoglycemia," low blood sugar ¹.

A further label passage concerns tumors. It says "GH-secreting tumors may enlarge in people with acromegaly" and that they need monitoring by MRI ¹.

Reports after approval include "systemic hypersensitivity reactions including anaphylactic reactions, laryngospasm, angioedema, generalized skin reactions" ¹. These are whole-body allergic reactions, and the label adds, "Some patients required hospitalization" ¹. In the studies run before approval, about 17 percent of treated patients developed "low titer, non-neutralizing anti-GH antibodies" ¹. A low titer is a low level in the blood, and a non-neutralizing antibody binds its target without blocking the target's action. The label says the antibodies' long-term clinical significance "is not known" ¹.

The longest safety record is a registry, a study that observes patients in ordinary care, of 2,221 patients with acromegaly treated for a mean of 8.5 years ¹. They could also receive other acromegaly treatments ¹. Of the 1,327 with normal liver enzymes at the start, 20 (1.5 percent) later exceeded 3 to 5 times the upper limit and 22 (1.7 percent) exceeded 5 times ¹. Lipohypertrophy was reported in 35 patients (1.6 percent) ¹. The label says comparing these rates with the original trial's "is not appropriate," because not every assessment was done for every patient ¹.

The label also gives MRI results for 1,795 of the registry's patients ¹. The label says 128 (7.1 percent) "were reported to have an increase," 310 (17.3 percent) "a decrease," 81 (4.5 percent) "both increase and decrease" and 1,276 (71.1 percent) "no change" ¹.

On pregnancy, the label says reports of use "are insufficient to establish a drug-associated risk" ¹. It also warns of "the potential for an unintended pregnancy," because treatment "may lead to improved fertility" ¹.

Under contraindications the label says "None" ¹. It reports that in clinical studies patients taking opioids often needed more of the drug to normalize IGF-1, by a mechanism it says "is not known" ¹.

In sport

The 2026 Prohibited List of the World Anti-Doping Agency (WADA) does not name pegvisomant ⁶. In section S2.2.3 it lists "Growth hormone (GH), its analogues and fragments," and names lonapegsomatropin, somapacitan and somatrogon as its examples of analogs ⁶.

The label calls pegvisomant "an analog of human growth hormone," and it blocks growth hormone's receptor instead of activating it ¹. The list does not say whether a receptor blocker of this kind falls under S2.2.3, and no WADA document read settles the question ⁶.

What JumpstartMD offers

JumpstartMD does not prescribe pegvisomant. Our peptide library covers it so you have the facts on its FDA status and the evidence, current as of November 10, 2026.

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Compounded medications are not FDA-approved, and FDA does not review their safety, effectiveness, or quality before they are marketed. A licensed clinician decides after an evaluation whether a peptide is appropriate for you, and not every patient will qualify.