Ipamorelin + MOTS-c Stack: Evidence, Mechanism Overlap, and Protocol

What has been tested in people?

Ipamorelin is a five-amino-acid synthetic peptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) that contains unnatural amino acids, first described in 1998 [5][1]. It releases growth hormone by acting at the ghrelin/GH-secretagogue receptor, not at the GHRH receptor. In rats and pigs it released growth hormone with potency similar to GHRP-6, and in swine it did not change FSH, LH, prolactin or TSH [5]. Most of the claims about how selective it is come from that animal work [5].

It was developed as an investigational drug for postoperative ileus, and that development was reportedly discontinued after disappointing phase 2 results [1][5]. FDA identified only one published ileus trial (Beck 2014), which enrolled 117 adults and analyzed 114 after bowel resection. Ipamorelin 0.03 mg/kg given intravenously twice daily from postoperative day 1 to 7 did not significantly shorten the median time to a first tolerated solid meal: 25.3 hours with ipamorelin versus 32.6 hours with placebo, p=0.15 [3][1]. Secondary bowel-recovery endpoints did not differ either [3].

Human pharmacokinetics come from a dose-escalation study in healthy men given single 15-minute intravenous infusions of 4.21 to 140.45 nmol/kg: terminal half-life about 2 hours, clearance 0.078 L/h/kg, steady-state volume of distribution 0.22 L/kg, and growth hormone rose in a single peak about 0.67 hours after the infusion [4].

MOTS-c (mitochondrial open reading frame of the 12S rRNA-c) is a 16-amino-acid peptide of about 2,174.6 g/mol, encoded in mitochondrial DNA and first reported in 2015 by Lee and colleagues in Cell Metabolism [2][6]. In mice, MOTS-c treatment prevented age-dependent and high-fat-diet-induced insulin resistance and diet-induced obesity, with skeletal muscle as the apparent main target; at the cellular level it inhibits the folate cycle and activates AMPK [6].

The mouse numbers are specific: injected MOTS-c at 0.5 mg/kg/day intraperitoneally produced about 20% lower body weight than controls after 8 weeks on a high-fat diet, and a late-life schedule of 15 mg/kg three times weekly from 23.5 months of age lengthened median lifespan from 912 to 970 days [2][9]. FDA notes that the molecular targets are unknown [2].

The human work has measured the body's own MOTS-c rather than injected peptide. In a randomized study of 30 healthy adults who did endurance exercise (n=10), resistance exercise (n=10) or nothing (n=10), circulating MOTS-c showed only a trend to rise after endurance exercise, and plasma levels were not related to fitness [10]. A second study found that exercise raises MOTS-c expression in skeletal muscle and in circulation; those participants were not given the peptide [9]. There is also a delivery question: in an in-vitro study, MOTS-c was quickly broken down in human blood [2].

Do the mechanisms overlap?

The primary targets are different. Ipamorelin acts at the ghrelin/GH-secretagogue receptor to release growth hormone [5]. MOTS-c acts on AMPK signaling inside cells; in mouse and cell studies it inhibited the folate cycle and activated AMPK [6].

The two stories touch at glucose, but only as separate observations in different species. FDA says that because ipamorelin stimulates the GH and IGF-1 axis it may carry the risks listed on approved growth hormone labels, which include glucose intolerance and diabetes [1], and in the ileus trial high blood sugar at discharge was recorded in 14.3% of ipamorelin patients versus 8.6% on placebo [1]. MOTS-c improved insulin sensitivity in mice [6]. No study has tested whether one affects the other.

Is there a dosing protocol?

The only ipamorelin doses on record in humans are intravenous: 0.03 mg/kg twice daily in the ileus trial, and single 15-minute infusions of 4.21 to 140.45 nmol/kg in volunteers [3][4]. Those are study doses in specific groups, not recommendations, and FDA found no human pharmacokinetic, safety or efficacy data for subcutaneous ipamorelin [1].

For MOTS-c, the only doses on record are the nominated products FDA reviewed: 5 mg and 10 mg subcutaneous injections [2]. Those come from a nomination, not from a dose-finding study. The mouse doses of 0.5 to 15 mg/kg cannot be converted into human doses, and FDA found no dose-response data [2].

So no schedule or cycle length can be derived from published research for either peptide, or for the pair [1][2].

Regulatory status: two different situations

Ipamorelin. It is not an FDA-approved drug, is not a component of one, and has no US Pharmacopeia monograph [1][5]. FDA lists ipamorelin acetate among bulk substances that may present significant safety risks for compounding by outsourcing facilities (large registered compounders); it was added September 29, 2023 and remains in category 2 on FDA's page dated 04/22/2026 [8][11]. FDA's stated concerns are immunogenicity from aggregation and impurities, the difficulty of characterizing a peptide with unnatural amino acids, and a published study that reported serious adverse events including death when ipamorelin was given intravenously for gastric motility [8]. For state-licensed pharmacies and physicians, ipamorelin appears in FDA's nominated-but-withdrawn table, and FDA's category 1 policy does not apply to it [8][12]. On October 29, 2024, FDA's Pharmacy Compounding Advisory Committee voted 0 yes, 12 no, 1 abstention on ipamorelin free base, and the same on the acetate, citing a lack of information supporting safety and efficacy [13]. It is not among the six peptides named in HHS's October 2026 draft enforcement-discretion policy [14].

MOTS-c. It is also not FDA-approved; FDA found no USP or National Formulary monograph and no product authorized by the European Medicines Agency [2]. It sits in the nominated-but-withdrawn table on FDA's safety-risk page, meaning it was previously in category 2 and its nominators withdrew it; removal from category 2 was not a finding that it is safe [8]. It appears in none of the three categories on FDA's list for state-licensed pharmacies and physicians (updated May 14, 2026) or on the list for outsourcing facilities (updated March 21, 2025) [12][11][15]. In July 2026 FDA staff recommended against adding it to the compounding list, citing inconsistent naming, no human safety or effectiveness data, no animal toxicity studies, and the existence of approved treatments for two of the nominated uses, obesity and osteoporosis [2]. On July 23, 2026 the advisory committee voted in favor of adding it, against the staff recommendation; that advice is non-binding and does not put MOTS-c on the list, which takes formal rulemaking [16][17].

HHS's draft policy, filed October 28, 2026, names MOTS-c acetate for subcutaneous or intramuscular injection among six peptides and says HHS does not intend to take enforcement action against state-licensed pharmacies, federal facilities or licensed physicians compounding with it if its conditions are met [17][14]. The notice states that it does not establish any rights for any person and is not binding on HHS or the public, and that HHS may revisit it, for example if a safety signal appears [17]. Compounded drugs are not FDA-approved, and FDA does not review their safety, effectiveness or quality before marketing [18].

Safety: what the records show

In the ileus trial, low potassium occurred in 12.5% of ipamorelin patients versus 3.4% on placebo, insomnia in 10.7% versus 5.2%, high blood sugar at discharge in 14.3% versus 8.6%, and serious adverse events in 17.9% versus 15.5% [1][3]. Two ipamorelin-treated patients died of surgical complications after bowel surgery for colon cancer; FDA said it is unclear whether the deaths were related to the drug but that they raise safety concerns [1].

FDA also expects growth-hormone-axis risks. Because ipamorelin stimulates GH and IGF-1, FDA says it may carry the risks listed on approved growth hormone labels (neoplasm, glucose intolerance and diabetes, intracranial hypertension, fluid retention, hypothyroidism, pancreatitis and others) and possibly QT prolongation, as with the approved GH stimulator macimorelin. FDA found no data showing it would not [1].

For MOTS-c, FDA found no human exposure data by any route, no animal toxicity studies and no immunogenicity data, and searches of its adverse-event database through March 9, 2025 retrieved no MOTS-c reports [2]. Its stated concern for injectable peptides is immunogenicity from aggregation and peptide-related impurities [2].

In sport, WADA names ipamorelin in S2.2.4 (growth hormone secretagogues and mimetics) and MOTS-c in S4.4.1 (metabolic modulators, AMPK activators). Both are prohibited at all times, in and out of competition [7][19].

What remains unknown

Whether injected MOTS-c survives long enough in human blood to produce active levels [2]. How the two peptides together would affect glucose: the only human glucose signal for ipamorelin is the ileus trial's blood sugar at discharge, 14.3% versus 8.6% [1], while MOTS-c's metabolic results come from mice [6].