Curious about tesamorelin vs. ipamorelin and how these two synthetic peptides stack up against each other?
Many researchers in the growth hormone therapy field are interested in the similarities and differences between tesamorelin and ipamorelin. Both of these peptides increase the synthesis and release of endogenous human growth hormone.
But they're slightly different in how they work, as well as in their potential benefits and side effects. Tesamorelin is an FDA-approved treatment for reducing abdominal fat in HIV-infected patients with lipodystrophy, while ipamorelin has yet to complete human clinical trials and is typically administered in conjunction with a GHRH like tesamorelin or CJC-1295.
In this A-Z guide, we’ll detail the similarities and differences between the two peptides to help interested researchers decide which peptide merits further investigation.
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What are Research Peptides?
Research peptides, known as peptide drug products, are at the forefront of ongoing GH therapy research and experimentation . They're essentially chains of molecules called amino acids — the same molecules that make up proteins. Peptides naturally occur in the body or can be synthesized in laboratory settings via chemical synthesis.
According to the United States Food & Drug Administration (FDA), any polymer composed of 40 or fewer amino acids can be considered to be a peptide. To date, there are over 100 peptide drug products marketed in the U.S., Europe and Japan — in a global market estimated to be worth over $20 billion .
Because peptide drug products are so promising, many scientists and researchers are eager to conduct further research. There are currently almost 500 peptides recognized by the FDA as having therapeutic value to potentially treat various diseases, including :
- Bone disorders
- Genetic disorders
- Infectious disease
- Cardiovascular problems
- Immune system
- Respiratory disorders
- Eye disorders
- Neurodegenerative problems
- Poor hormonal health
- Bone disorders
Some of the most commonly used GHRH-promoting peptide drug products include tesamorelin, ipamorelin and sermorelin. In the following section, we will take a closer look at tesamorelin.
What is Tesamorelin?
Tesamorelin is a synthetic GHRH analogue that was created in the 1990s by the Canadian technology company Theratechnologies . It has been approved by the FDA to treat visceral adiposity (excessive fat around the midsection) in HIV-infected patients with lipodystrophy . For this exclusive purpose, it is sold under the trade name EGRIFTA.
Mechanism of Action
The chemical structure of tesamorelin is almost identical to the hypothalamic peptide “growth hormone-releasing hormone” (GHRH), which occurs naturally in the body. This hormone plays a role in regulating the synthesis and release of human growth hormone (HGH).
Tesamorelin works by binding to receptors in the pituitary gland, and stimulating the gland to produce and release even more HGH. The result is an increase in the concentration of HGH in the blood . By up-regulating the amount of HGH in the bloodstream, tesamorelin offers several research-backed benefits.
Benefits of Tesamorelin
Tesamorelin's main clinical benefit is that it helps treat HIV-positive patients who suffer from lipodystrophy, a condition that leads to excessive visceral adipose tissue (VAT) around the trunk. Tesamorelin has been shown to decrease VAT and help decrease the waist circumference of adults with HIV .
In other clinical trials involving HIV-infected adults, tesamorelin has been shown to help decrease muscle fat while simultaneously increasing muscle area  and lowering levels of overall abdominal fat  caused by long-term antiretroviral therapy. Tesamorelin therapy has been shown to trigger lipolysis, or fat burning, especially around the abdominal area .
To date, the only tesamorelin research conducted on adults without HIV involved measuring levels of neurotransmitters in the brain. A Washington state study found that tesamorelin helps lower levels of myo-inositol (MI), an osmolyte linked to early-onset Alzheimer's disease . In the next section, ipamorelin will be introduced and discussed.
What is Ipamorelin?
Ipamorelin is a pentapeptide that was developed by Novo Nordisk, a Danish pharmaceutical company. Ipamorelin is composed of a chain of five amino acids, making it much simpler than tesamorelin. It is chemically very similar to the body's own natural growth hormone-releasing peptide (GHRP)-1, with the main difference being that it lacks the central dipeptide Ala-Trp found in GHRP-1 .
Unlike tesamorelin, ipamorelin has not been approved by the FDA for any use, and has yet to be reviewed in human clinical trials. All data related to ipamorelin's efficacy, benefits, and safety is from animal studies.
Mechanisms of Action
Like tesamorelin, ipamorelin is a GH secretagogue, meaning that it promotes the synthesis and release of GH in vitro and in vivo. Animal studies have shown that ipamorelin is able to bind to primary rat pituitary cells and stimulate the release of GH into the blood. It binds to cells in the pituitary gland, prompting the release of additional HGH into the bloodstream .
The other effect of ipamorelin is to suppress somatostatin, which is a hormone that inhibits the production of HGH. By reducing this HGH inhibitor, ipamorelin indirectly increases the body's ability to produce additional HGH.
Benefits of Ipamorelin
Similar to tesamorelin, the main benefit of ipamorelin is that it appears to increase HGH levels. Based on research data, composed of animal studies, the following is worth noting:
- The results of animal studies indicate that ipamorelin appears to be a “selective” GH secretagogue. This means it only up-regulates HGH, but not other hormones like cortisol or adrenocorticotropic hormone (ACTH) .
- In a study involving young female rats, ipamorelin was shown to help increase “body weight gain” and enhance “in vitro basal and ipamorelin or GHRH-stimulated GH release” .
- A study involving groups of 8-month-old female rats found that ipamorelin could “counteract the catabolic effects of glucocorticoid (GC) on skeletal muscles and bone” .
Ipamorelin has been shown to induce longitudinal bone growth in rats .
Following this review of the benefits of ipamorelin, we can now discuss whether researchers should investigate tesamorelin or ipamorelin as their HGHR peptide of choice.
Best Human Growth Hormone-Releasing Peptide
The studies cited above have confirmed that both tesamorelin and ipamorelin appear to offer similar benefits, but which one is superior from a research standpoint?
A key difference between these peptides is that while they both appear to increase the secretion and production of HGH in vitro and in vivo, only tesamorelin has undergone human clinical trials and has been approved by the FDA.
Another key difference between these two peptides is that ipamorelin does not adversely affect ACTH or cortisol, at least not based on the rat and swine studies .
In the following section, we will discuss the differences between tesamorelin and ipamorelin in greater detail.
Differences between Tesamorelin and Ipamorelin
While there are strong similarities between tesamorelin and ipamorelin, researchers will note that these peptides differ significantly in the following ways.
The primary difference between ipamorelin vs. tesamorelin is chemical.
They are both peptides, thus short chains of amino acids. But tesamorelin is much longer at 44 amino acids in length. By contrast, ipamorelin is made up of just five amino acids.
Mechanism of action
The structural difference between tesamorelin and ipamorelin means that the two have a slightly different mechanism of action. Tesamorelin is a stabilized peptide analogue of growth hormone-releasing hormone (GHRH) while ipamorelin is a growth hormone-releasing secretagogue. They mimic slightly different chemicals in the body and bind to different receptors.
So while they have the same ultimate effect of increasing HGH, they do so in slightly different ways. Tesamorelin is an FDA-approved treatment for reducing excess abdominal fat in HIV-infected patients with lipodystrophy and may be administered as a standalone treatment. Ipamorelin, on the other hand, has yet to pass human clinical trials and is typically administered in conjunction with another peptide.
Ipamorelin vs. Tesamorelin Cost
Another key difference between ipamorelin and tesamorelin is cost.
How much does ipamorelin cost? Ipamorelin costs about $50 for 5 mg while tesamorelin costs about $70 for 5 mg. Depending on the dosing protocol adopted by the researcher, ipamorelin may cost significantly less than tesamorelin.
How Are Tesamorelin and Ipamorelin Dosed and Cycled?
This section will outline how tesamorelin and ipamorelin are typically dosed and cycled.
Tesamorelin Dosage and Administration
The recommended dose of tesamorelin (EGRIFTA™) for HIV-positive adult patients with lipodystrophy is 2 mg injected subcutaneously once daily .
In the clinical context, patients are typically instructed to follow this dosing schedule:
- One subcutaneous injection containing 2 mg tesamorelin daily
- Taken at the same time each day, ideally before bed
- Five days per week
- Continue for 60 days, with one month off
Ipamorelin Dosage and Administration
In terms of ipamorelin dosage, this peptide has not been approved for human use and therefore has no “recommended” dosage or cycling structure. Ipamorelin was investigated in phase II clinical trials for the treatment of postoperative ileus; however, these trials were discontinued due to lack of efficacy .
Participants in this small proof of concept study were given intravenous infusions of 0.03-mg/kg ipamorelin twice daily for 7 days after undergoing small and large bowel resection by open or laparoscopic surgery. The study found that “ipamorelin 0.03-mg/kg twice daily for up to 7 days was well tolerated” . There is clearly potential for further research in terms of ipamorelin’s long-term safety and effects.
There is strong research interest in the application of both tesamorelin and ipamorelin to improve both body composition and physical performance. However, there are no official or published figures to indicate the dosage at which either peptide should be administered to these ends .
However, a WADA-funded study into the effects of growth hormone (GH) on athletic performance gives some insight into how peptides may be administered. In the study, recreational athleted were administered GH at a dose of 2 mg injected subcutaneously once daily . This offers some indication of how GH may be supplemented to increase physical performance and how ipamorelin may be administered at a lower dose in conjunction with a GHRH like tesamorelin or CJC-1295.
How to Order Research Peptides online
Researchers can legally buy both tesamorelin and ipamorelin online for limited purposes only. But the researcher-consumer should exercise due caution: not every vendor is trustworthy. There are many vendors that sell low-purity peptides that don’t work, and can even be dangerous. Researchers interested in ordering peptides online should ensure that they source them from a reputable vendor.
Researchers interested in identifying trustworthy tesamorelin and ipamorelin vendors may consider the following criteria:
- Does the website have a clear disclaimer that outlines the terms and conditions of the peptides?
- Does the site publish certificates of analysis that show the purity of the peptides?
- Are there independent reviews of the vendor on third-party websites?
- Can researchers use secure payment methods?
- Is reasonably priced shipping available?
In our opinion, the most reliable and consistent vendor to buy research peptides from online is Peptide Sciences. We've only had excellent experiences and we know that they offer extremely high-quality peptides.
The main benefits of Peptide Sciences include:
- American-made peptides with publicly available certificates of analysis.
- Convenient shipping options with very quick delivery.
- Shipping to most countries in the world.
- Secure payment options, including accepting cyber currencies like Bitcoin.
- Great customer service with a strong product guarantee.
While we have no doubt that researchers will have a positive experience with Peptide Sciences, we wanted to outline relevant side effects and safety concerns linked to both tesamorelin and ipamorelin.
Side effects and Safety Concerns
So both tesamorelin and ipamorelin appear to be effective at promoting GH in the body. But are they safe? What are the side effects of ipamorelin and tesamorelin?
The short answer is that only tesamorelin has undergone human clinical trials and has received FDA approval for an extremely limited purpose. Ipamorelin studies are lacking overall and this merits further research.
Here’s what we know.
Tesamorelin side effects
Tesamorelin has only been studied in HIV-positive adults. Results show that the most common side effects are:
- Redness, itching, pain, swelling, and irritation at the site of injection
- Muscle aches
Additionally, tesamorelin has been linked to glucose intolerance and found to increase the risk of type 2 diabetes mellitus. The drug is contraindicated during pregnancy .
Ipamorelin side effects
As ipamorelin has not been approved for human use, ipamorelin side effects require further research. As a GHRH secretagogue that is subcutaneously injected, ipamorelin likely causes side effects related to frequent injections such as pain, rash or soreness at injection sites, in common with other forms of GH therapies .
Avoiding side effects
Researchers who are new to working with peptides are advised to screen test subjects for pre-existing conditions and follow approved protocols to minimize the risk of injection-related complications.
Ipamorelin vs. Tesamorelin | Verdict
Between tesamorelin and ipamorelin, which ultimately wins out?
From an experimental standpoint, tesamorelin has the clear advantage of having been evaluated in human clinical trials and approved by the FDA for use in humans. It still presents many avenues for further research, such as long-term cardiovascular benefits and safety.
By comparison, ipamorelin has yet to receive FDA approval and remains a research peptide that is typically taken with a GHRH receptor agonist like tesamorelin itself or CJC-1295.
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