Drug information

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Other Names
Genotropin, Humatrope, Nutropin AQ NuSpin, Nutropin, Norditropin FlexPro, Omnitrope, Saizen, Zomacton (brand products for the treatment of growth disorders and growth hormone deficiency); Zorbtive (brand product for the treatment of short bowel syndrome); Serostim (brand product for the treatment of HIV wasting or cachexia); r-hGH, recombinant hGH, recombinant human GH, recombinant human growth hormone, somatotropin
Drug Class
Immune Modulators
Registry Number
12629-01-5 (CAS)
Chemical Name

Growth hormone (human)

Chemical Class
Carboxylic acids and derivatives
Phase of Development

Somatropin is in Phase 2 development as an immune modulator for the treatment of HIV infection.

FDA-Approved Product for HIV-Related Treatment: Somatropin is FDA-approved under the brand name Serostim for the treatment of HIV-associated wasting or cachexia.

(Compound details obtained from PubChem,1 Clinical and Experimental Immunology article,2 DrugBank website,3 ClinicalTrials.gov,4 and Serostim Full Prescribing Information5)


What is somatropin?What is somatropin?

What is somatropin?

Somatropin is a drug that has been approved by the U.S. Food and Drug Administration (FDA) for various uses, though it is mainly used to treat growth disorders in children and growth hormone deficiency in adults.3,6,7 Somatropin is FDA-approved under the brand name Serostim to treat HIV-associated wasting or cachexia in people with HIV. Off-label use of somatropin may include treatment of HIV-associated lipodystrophy syndrome.5,8

As an investigational HIV drug, somatropin belongs to a group of drugs called immune modulators.2 Immune modulators (also called immunomodulators) are substances that help to activate, boost, or restore normal immune function. Researchers have studied whether somatropin in combination with antiretroviral therapy (ART) could help reduce the size of the latent HIV reservoir.2,4

To learn how investigational drugs are tested during clinical trials, read the HIVinfo What is an Investigational HIV Drug? and HIV and AIDS Clinical Trials fact sheets.

Select clinical trials of somatropinSelect clinical trials of somatropin

Select clinical trials of somatropin

Study Names: ACTG A5198s; ACTG A5174; NCT00050921

Phase: Not available
Status: This study has been completed.
Location: United States
Purpose: The purpose of this study was to evaluate whether somatropin could increase naive CD4 cell production in people who had incomplete immune recovery while on ART.(Naive CD4 cells are newly made CD4 cells that have not yet been activated by antigen.)
Selected Study Results: Results published in AIDS Research and Human Retroviruses (2010) showed that somatropin 1.5 mg daily added to ART (Arm A) did not result in a significant change in naive CD4 cell count or percentage from baseline to Week 24, as compared to ART alone (Arm B). The primary endpoint of at least a 10% increase in naive CD4 cell percentage was achieved by only one participant in Arm A. After Week 24, participants in Arm A continued on their current dose of somatropin and participants in Arm B added somatropin 3.0 mg daily. By Week 48, participants in both arms had significant increases from baseline in total and naive CD4 cell counts.10

Study Names: CTN 298; NCT03091374

Phase: 2
Status: This study is ongoing, but not recruiting participants.
Location: Canada
Purpose: The purpose of this study was to evaluate whether somatropin could reduce the latent HIV reservoir in people with viral suppression and immune recovery on suppressive ART.4,11,12
Selected Study Results: Results presented at CROI 2021 showed that somatropin added to ART resulted in a trend towards a reduction in the size of the replication competent latent HIV reservoir from baseline to Week 48.11 (The replication competent latent HIV reservoir refers to the pool of latently infected cells in the body that are capable of producing new HIV.)

Study Name: NCT00071240

Phase: 2
Status: This study has been completed.
Location: United States
Purpose: The purpose of this study was to evaluate whether somatropin could increase the size and function of the thymus and increase the number of naive and total T cells in people with persistently low CD4 counts despite viral suppression on ART.13,14
Selected Study Results: Results published in The Journal of Clinical Investigation (2008) showed that somatropin treatment increased the size of the thymus. Somatropin treatment also enhanced the function of the thymus, as shown by an increased frequency of TCR rearrangement excision circles (TRECs) in peripheral blood mononuclear cells (PBMCs) and number of circulating naive and total CD4 cells. (TRECs are DNA byproducts of T-cell development and are markers for how well the thymus is functioning.)14

Study Names: VIHCREC01; NCT00287677

Phase: 4
Status: This study has been completed.
Location: Spain
Purpose: The purpose of this study was to evaluate whether somatropin could boost cellular immunity and humoral immunity to commonly used vaccines in people with severe immunosuppression despite viral suppression on ART.15
Selected Study Results: Results published in Immunology (2011) showed that thymus reconstitution through treatment with somatropin restored specific CD4 cell and antibody immune responses in participants with immunosuppression on ART.16

For more details on the studies listed above, see the Health Professional version of this drug summary.

The following clinical trials have also evaluated somatropin as an immune modulator:

  • NCT00119769: A Phase 4 substudy that evaluated the effect of somatropin on immune function in people with HIV on ART.2,17
  • NCT01130376: A Phase 1 study that explored whether an investigational therapeutic HIV vaccine called GTU-MultiHIV B boosted with somatropin and other immune modulators could improve immune responses in people with viral suppression on ART.18,19

What side effects might somatropin cause?What side effects might somatropin cause?

What side effects might somatropin cause?

One goal of HIV research is to identify new drugs that have fewer side effects. The following side effects were observed in some of the studies of somatropin listed above.

ACTG A5174 (NCT00050921):

Among the 60 participants in this study, eight dropped out because of a side effect. In six participants, carpal tunnel syndrome that was either suspected or diagnosed was likely related to somatropin. One participant entered the study with anal cancer, which worsened during the study, possibly because of somatropin.9,10

CTN 298 (NCT03091374):

In this study, only three out of 12 participants who started taking somatropin completed 48 weeks of treatment. The primary reason for study drug discontinuation was musculoskeletal pain, which occurred in six participants.4,11


In this study, three participants stopped taking somatropin and dropped out of the study because of a side effect (diabetes in two participants and carpal tunnel syndrome in one participant). In seven other participants, the somatropin dose was temporarily withheld or reduced by at least half because of side effects.14

Overall, most of the study participants reported having a side effect of at least moderate severity. Most of the side effects were known effects of somatropin treatment and included joint pain, abnormal glucose metabolism, swelling, and carpal tunnel syndrome. There were three reported cases of lymphoma, but only one occurred in a participant who had received somatropin. Three cases of hand tenosynovitis (inflammation of a tendon and the membrane surrounding the tendon) were reported in participants receiving somatropin.14

VIHCREC01 (NCT00287677):

During this study, four participants had their somatropin dose reduced because of a side effect, including joint or muscle pain, swelling of the arms or legs, and nerve damage. In some participants, the somatropin dose had to be reduced at least twice to manage the side effect.15,16

Side effects reported in participants who received somatropin included joint pain, swelling of the hand, muscle pain, nerve damage, carpal tunnel syndrome, weakness, and acute respiratory infection. Although the side effects were generally mild, somatropin treatment was stopped because of carpal tunnel syndrome in one participant and swelling of the hand in another participant. One participant was hospitalized because of acute respiratory infection.16

Because somatropin is still being studied, information on possible side effects of the drug is not complete. As testing of somatropin continues, additional information on possible side effects will be gathered.

Additional information on side effects that are known to be associated with somatropin can be found in the FDA-approved Full Prescribing Information for Serostim.

Where can I get more information about clinical trials studying somatropin?Where can I get more information about clinical trials studying somatropin?

Where can I get more information about clinical trials studying somatropin?

More information about somatropin-related research studies is available from ClinicalTrials.gov

Some clinical trials may be looking for volunteer participants. Your health care provider can help you decide whether participating in a clinical trial is right for you. For more information, visit NIH Clinical Research Trials and You.



  1. National Center for Biotechnology Information. PubChem Compound Summary for SID 472423450, Somatropin. Accessed October 25, 2023
  2. Herasimtschuk AA, Hansen BR, Langkilde A, Moyle GJ, Andersen O, Imami N. Low-dose growth hormone for 40 weeks induces HIV-1-specific T cell responses in patients on effective combination anti-retroviral therapy. Clin Exp Immunol. 2013;173(3):444-453. doi:10.1111/cei.12141. Accessed October 25, 2023
  3. DrugBank. Somatotropin. Accessed October 25, 2023
  4. McGill University Health Center. A proof-of-concept study to assess the effect of recombinant human growth hormone on the size of the replication-competent viral reservoir in HIV-infected individuals on suppressive antiretroviral therapy. In: ClinicalTrials.gov. Bethesda (MD): National Library of Medicine (US). Registered on March 21, 2017. NLM Identifier: NCT03091374. Accessed October 25, 2023
  5. EMD Serono, Inc. Serostim: full prescribing information, February 2, 2022. DailyMed. Accessed October 25, 2023
  6. Reh CS, Geffner ME. Somatotropin in the treatment of growth hormone deficiency and Turner syndrome in pediatric patients: a review. Clin Pharmacol. 2010;2:111-122. Accessed October 25, 2023
  7. Cai Y, Xu M, Yuan M, Liu Z, Yuan W. Developments in human growth hormone preparations: sustained-release, prolonged half-life, novel injection devices, and alternative delivery routes. Int J Nanomedicine. 2014;9:3527-3538. doi:10.2147/IJN.S63507. Accessed October 25, 2023
  8. Generali JA, Cada DJ. Recombinant human growth hormone: HIV-related lipodystrophy. Hosp Pharm. 2014;49(5):432-434. doi:10.1310/hpj4905-432. Accessed October 25, 2023
  9. National Institute of Allergy and Infectious Diseases (NIAID). Improving immune reconstitution with growth hormone in HIV-infected subjects with incomplete CD4+ lymphocyte restoration on highly active antiretroviral therapy (HAART). In: ClinicalTrials.gov. Bethesda (MD): National Library of Medicine (US). Registered on December 30, 2002. NLM Identifier: NCT00050921. Accessed October 25, 2023
  10. Smith K, Zheng L, Bosch R, et al. Treatment with recombinant growth hormone is associated with modest improvement in CD4 lymphocyte reconstitution in HIV-infected persons on antiretroviral therapy: results of ACTG A5174. AIDS Res Hum Retroviruses. 2010;26(4):425-432. doi:10.1089/aid.2009.0052. Accessed October 25, 2023
  11. Chomont, N. Effect of recombinant growth hormone on HIV reservoirs: a pilot study (CTN 298). Webcast presented at: Conference on Retroviruses and Opportunistic Infections (CROI); March 6-10, 2021; Virtual. Accessed October 25, 2023
  12. Treatment Action Group website. Research toward a cure trials. Accessed October 25, 2023
  13. National Institute of Allergy and Infectious Diseases (NIAID). The use of recombinant growth hormone to enhance T-cell production in adults infected with HIV-1. In: ClinicalTrials.gov. Bethesda (MD): National Library of Medicine (US). Registered on October 16, 2003. NLM Identifier: NCT00071240. Accessed October 25, 2023
  14. Napolitano LA, Schmidt D, Gotway MB, et al. Growth hormone enhances thymic function in HIV-1–infected adults. J Clin Invest. 2008;118(3):1085-1098. doi:10.1172/JCI32830. Accessed October 25, 2023
  15. Germans Trias i Pujol Hospital. Double strategy to induce and expand the T cell repertoire by the administration of growth hormone and vaccination in HIV-1 Infected patients. In: ClinicalTrials.gov. Bethesda (MD): National Library of Medicine (US). Registered on February 6, 2006. NLM Identifier: NCT00287677. Accessed October 25, 2023
  16. Plana M, Garcia F, Darwich L, et al. The reconstitution of the thymus in immunosuppressed individuals restores CD4-specific cellular and humoral immune responses. Immunology. 2011;133(3):318-328. doi:10.1111/j.1365-2567.2011.03442.x. Accessed October 25, 2023
  17. Hvidovre University Hospital. The effect of low-dose human growth hormone therapy in HIV infected patients on highly active antiretroviral therapy (HAART). In: ClinicalTrials.gov. Bethesda (MD): National Library of Medicine (US). Registered on July 7, 2005. NLM Identifier: NCT00119769. Accessed October 25, 2023
  18. Imperial College London. A randomised, open labelled, Phase I, safety, toxicity, and exploratory immunogenicity evaluation of therapeutic immunisation +/- IL-2, GM-CSF and growth hormone in HIV-1 infected subjects receiving highly active anti-retroviral therapy. In: ClinicalTrials.gov. Bethesda (MD): National Library of Medicine (US). Registered on May 25, 2010. NLM Identifier: NCT01130376. Accessed October 25, 2023
  19. Herasimtschuk A, Downey J, Nelson M, et al. Therapeutic immunisation plus cytokine and hormone therapy improves CD4 T-cell counts, restores anti-HIV-1 responses and reduces immune activation in treated chronic HIV-1 infection. Vaccine. 2014;32(51):7005-7013. Accessed October 25, 2023

Last Reviewed: October 25, 2023