MOTS-c Compounding Pharmacy: 503A vs 503B, What You Need to Know Before You Buy

Does the pharmacy-versus-outsourcing question even apply to MOTS-c?

Compounding a bulk drug substance at a state-licensed pharmacy requires one of three things: the substance complies with a USP or National Formulary monograph, it is a component of an FDA-approved drug product, or it appears on FDA's bulks list for state-licensed pharmacies [8]. MOTS-c meets none of the three.

FDA's July 2026 review found no USP or National Formulary monograph for MOTS-c, no listing in the European or Japanese pharmacopeias, and no product authorized by the European Medicines Agency, and the peptide is not a component of any approved drug [1]. Nor is it on FDA's bulks list for state-licensed pharmacies [8].

FDA's interim policy sorts nominated substances into three categories [8]. MOTS-c appears in none of the three on the list for state-licensed pharmacies and physicians, updated May 14, 2026, so the category 1 policy, under which FDA says it does not intend to take action against a compounder that meets the guidance conditions, does not cover it [7][8].

Outsourcing facilities have their own list, updated March 21, 2025, and MOTS-c is not on it. FDA also found that no outsourcing facility reported compounding the peptide from January 2017 through December 2025 [1][2].

How do state-licensed pharmacies and outsourcing facilities differ?

Federal law sets out the conditions under which compounded human drug products from state-licensed pharmacies are exempt from the FD and C Act provisions on FDA approval, current good manufacturing practice and adequate directions for use, and one of those conditions is that the drugs are compounded on receipt of valid patient-specific prescriptions [10].

The Drug Quality and Security Act, enacted November 27, 2013, created a separate voluntary category of compounders called outsourcing facilities. Outsourcing facilities are subject to current good manufacturing practice, may distribute compounded drugs either pursuant to a patient-specific prescription or in response to an order from a health care provider that is not for an identified individual patient, are inspected by FDA on a risk-based schedule, and must report adverse events and give FDA information about what they compound [10]. Compounded drugs are not FDA-approved, and FDA does not review them for safety, effectiveness or quality before they reach patients [10].

For MOTS-c, both lists point the same way: the peptide is on neither one [7][2].

What is MOTS-c's current federal status?

MOTS-c sat in category 2, FDA's designation for bulk substances that may present significant safety risks, before its nominator withdrew it. It now sits in the nominated-but-withdrawn table on FDA's safety-risk page, content dated April 22, 2026 [11]. FDA's stated concerns were that it 'has not identified any human exposure data on drug products containing MOTs-C administered via any route of administration', that the substance lacks important safety information, and that injectable peptides may raise immunogenicity risk from aggregation and peptide-related impurities. Removal from category 2 was not a finding that MOTS-c is safe [11].

FDA staff went further in July 2026 and recommended that neither the free base nor the acetate be added to the pharmacy bulks list. The briefing document cited inconsistent naming, no impurity, aggregate or endotoxin data, unknown use in compounding, no human safety or effectiveness data, no animal toxicity studies, and the existence of FDA-approved treatments for obesity and osteoporosis, two of the nominated uses [1].

What did the July 2026 advisory committee vote mean?

The Pharmacy Compounding Advisory Committee took up MOTS-c on July 23, 2026 alongside BPC-157, KPV and TB-500, with obesity and osteoporosis as the uses FDA reviewed [3]. The committee voted in favor of adding it to the bulks list, against the staff recommendation. That is advice only and does not bind FDA, and adding a substance takes formal rulemaking; MOTS-c is not on the list [3][4].

The original nomination proposed 5 mg and 10 mg subcutaneous injections for insulin resistance, obesity, osteoporosis, vascular calcification, muscle and fat metabolism, and longevity [1].

What does the October 2026 HHS draft policy say?

HHS filed a draft enforcement-discretion policy on October 28, 2026, Federal Register document 2026-22192, scheduled for publication October 30, 2026 with comments due two weeks after publication [4]. It names MOTS-c among six peptides, with BPC-157, epitalon, KPV, Semax and TB-500, and covers MOTS-c acetate given by subcutaneous or intramuscular injection [4][5].

Under the draft, HHS 'does not intend to take enforcement action' against a state-licensed pharmacy, federal facility or licensed physician compounding with it if the policy's conditions are met, including a single active ingredient, a patient-specific prescription, an FDA-registered manufacturer with a certificate of analysis, and a label reading 'This is a compounded drug product. Not for resale.' [4][5]

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 the policy if a safety signal or product quality issue arises [4]. It is not an FDA approval and does not put MOTS-c on any list [4].

What has been measured in people?

Human studies so far measured the body's own MOTS-c, not an injected product. In a 2021 Nature Communications study, exercise induced endogenous MOTS-c expression in skeletal muscle and in the circulation [12]. A 2021 randomized trial in the Journal of Applied Physiology assigned 30 healthy adults to endurance exercise (n=10), resistance exercise (n=10) or a control group (n=10). Circulating humanin rose after endurance exercise, MOTS-c showed only a trend to increase, and plasma levels of the two peptides were not related to fitness [13]. Nobody in either study received MOTS-c [12][13].

What do the animal and laboratory data show?

MOTS-c was first reported in 2015 in Cell Metabolism as a 16-amino-acid peptide from a short open reading frame in the mitochondrial 12S rRNA, with skeletal muscle as its main target and AMPK activation downstream of inhibited folate-cycle metabolism. In mice it prevented age-dependent and high-fat-diet-induced insulin resistance, as well as diet-induced obesity [6].

Injected MOTS-c reduced weight gain on a high-fat diet, about 20% lower body weight after 8 weeks at 0.5 mg/kg/day intraperitoneally, and improved insulin sensitivity and exercise performance; 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 [1]. FDA noted that the molecular targets are unknown and that no dose-response relationships were assessed [1]. One laboratory finding bears directly on the injection question: MOTS-c is quickly broken down in human blood in vitro, which raises the question whether injecting it can produce active levels in a person [1].

Is there an approved dose or human safety data?

The nominated products were 5 mg and 10 mg subcutaneous injections, and the rodent doses of 0.5 to 15 mg/kg cannot be converted into human doses [1]. FDA found no pharmacokinetic data for MOTS-c in humans or in live animals; the only kinetic observation is rapid breakdown in human blood in vitro [1].

FDA's searches of its adverse-event database through March 9, 2025 retrieved no MOTS-c reports [1]. Its stated concern for injection is immunogenicity from aggregation and peptide-related impurities, and no immunogenicity data exist for this 16-amino-acid peptide. No animal toxicity studies were found either, so its safety in humans is unknown [1].

Is MOTS-c prohibited in sport?

WADA's Prohibited List names MOTS-c in section S4.4.1 among activators of AMP-activated protein kinase, and prohibits it at all times, in and out of competition; S4.4 substances are non-Specified Substances [9]. It is on the 2026 List, in force since January 1, 2026, and remains on the 2027 List in the tracked-changes version dated August 26, 2026; FDA notes it was already on the 2024 List [9][14][1].

What should you check before paying for MOTS-c?

The HHS draft's conditions apply to MOTS-c acetate only, by injection only, and do not add MOTS-c to an FDA bulks list [4][5]. A state-licensed pharmacy cannot lean on FDA's category 1 policy here, because MOTS-c is not in category 1 [7][8]. FDA found no reported outsourcing-facility history with the peptide [1]. And there is no approved human dose and no human pharmacokinetic data to compare a vial against [1].