InsufficientPreprint
This paper presents a theoretical hypothesis arguing that current GLP-1 and dual GIP/GLP-1 receptor agonist therapies (e.g., semaglutide, tirzepatide) produce weight loss plateaus because they only address one side of what the authors term the "mass balance equation" — net mass inflow (NMI) — while net mass outflow (NMO) passively and actively declines over time. The authors propose a "mass balance model" (MBM) as an alternative explanatory framework to the conventional energy balance model, framing the plateau as a predictable physical consequence rather than a vague compensatory metabolic adaptation. Based on this framework, the authors hypothesize that combining an NMI-reducing agent with an NMO-stabilizing or NMO-enhancing agent could produce greater, more durable weight loss and improved body composition. Candidate NMO-targeting agents discussed include SGLT2 inhibitors, activin/myostatin pathway inhibitors, and mitochondrial uncouplers. The paper is entirely theoretical; no original experimental data, clinical trials, or systematic evidence synthesis are presented. Its primary limitation is that the MBM framework and the dual-action hypothesis remain untested in human or animal studies.
Unknown journal · Jun 2026DOI ↗ Insufficient
This scoping review, conducted following PRISMA-ScR guidelines, examines whether GLP-1 receptor agonists (GLP-1 RAs) — including semaglutide, liraglutide, tirzepatide, and retatrutide — may interfere with autologous fat grafting outcomes. The authors note that millions of patients using GLP-1 RAs for weight loss now present to aesthetic surgeons with facial volume loss and soft tissue deflation, conditions commonly treated with fat grafting. The review synthesizes preclinical and clinical evidence on how GLP-1 RA medications affect adipocyte biology, adipose-derived stem cell (ASC) function, and tissue revascularization. The authors identify several theoretical interference points: GLP-1-mediated adipocyte "browning" and thermogenic activation (including UCP1 upregulation), enhanced lipolysis via ATGL and HSL pathways, suppression of white adipogenic differentiation in ASCs favoring beige/thermogenic lineages, and altered angiogenic and inflammatory signaling during the revascularization window critical to graft survival. The authors explicitly acknowledge that no clinical or preclinical studies have directly examined fat graft outcomes in patients receiving these therapies. The review's conclusions are framed as hypothesis-generating, and any clinical considerations offered are described as mechanism-based rather than evidence-based. This limits the paper's direct applicability to patient care.
Aesthetic surgery journal · Jun 2026DOI ↗ Insufficient
This brief report, authored for nurse practitioners (NPs), examines the clinical and regulatory challenges arising from patient-driven "microdosing" of GLP-1 receptor agonists (semaglutide and tirzepatide) in the context of FDA restrictions on compounded versions following resolution of drug shortages. The authors describe how affordability barriers push patients toward subtherapeutic dosing strategies, unregulated "research-grade" peptides purchased online, and unsupervised sources such as medical spas. The paper outlines specific safety concerns associated with these practices, including pen manipulation, medication sharing, compounded vials, and dosing errors, as well as the side effect profiles encountered. It also explores how provider weight bias may inadvertently drive patients toward unregulated alternatives and offers practical stigma-reduction strategies for clinical encounters. The authors discuss the legal risks of compounded "copies" and acknowledge a narrow legitimate role for compounding in patients with documented allergies. As a brief report rather than an empirical study, the paper does not present original data or a systematic review; its conclusions are based on regulatory context, clinical observation, and expert opinion. Its primary value lies in synthesizing emerging practice-relevant issues for NPs navigating a rapidly evolving regulatory environment.
Journal of the American Association of Nurse Practitioners · May 2026DOI ↗ Insufficient
This analytical chemistry study examined compounded tirzepatide products combined with vitamin B12 analogs that are widely marketed in the United States as alternatives to FDA-approved tirzepatide. Researchers collected samples from multiple U.S. market sources and subjected them to various analytical methods to assess peptide-related impurity profiles and potency. The key finding was the identification of a previously unknown chemical impurity generated by a reaction between tirzepatide and certain B12 analogs. This impurity was described as widespread across the tested samples and present at substantial levels. The authors note that compounded tirzepatide-B12 combinations are mass-marketed without undergoing formal evaluation of potency or impurity profiles, unlike FDA-approved products. The study does not characterize the clinical effects of the identified impurity, which remains unknown. Limitations include the absence of clinical outcome data, lack of information on the specific analytical thresholds used, and no assessment of patient exposure or harm. The authors conclude that the findings highlight quality-control risks associated with compounded therapies marketed outside the drug-approval regulatory framework and reinforce the rationale for pre-market testing and FDA oversight.
Expert opinion on drug safety · Apr 2026DOI ↗ InsufficientPreprint
This study analyzed a large, publicly available independent testing dataset of 6,441 samples spanning fourteen peptide compounds sold through largely unregulated gray market channels directly to consumers. Compounds examined included BPC-157, semaglutide, tirzepatide, PT-141, TB-500, thymosin beta-4, and others marketed for purposes such as injury recovery, muscle growth, fat loss, and athletic performance. Researchers applied two quality acceptance frameworks — one approximating standards for 503A compounded medications and a stricter model reflecting FDA-approved drug production standards — to assess purity, measured abundance, and endotoxin burden. The study found that between 41.6% and 71.1% of samples failed to meet basic quality criteria depending on the framework applied, and measurable endotoxin contamination was detected in 15% of samples. Gray market peptides were consistently cheaper than FDA-approved alternatives, though cost differentials varied widely (e.g., 72.8% higher for tirzepatide vs. 3,850% higher for PT-141 when comparing FDA-approved options). The authors concluded that consumer-directed third-party testing improves transparency but captures only a fraction of the full safety profile relevant to patients self-administering injectable compounds. Key limitations include reliance on a secondary dataset not collected under controlled research conditions and the inability to assess many other safety dimensions beyond purity and endotoxin levels.
Unknown journal · Apr 2026DOI ↗ InsufficientPreprint
This narrative review examines the pharmacogenomics of GLP-1 receptor agonists — principally semaglutide (Ozempic®/Wegovy®) and the dual GIP/GLP-1 agonist tirzepatide (Mounjaro®/Zepbound®) — with a focus on explaining the wide inter-individual variability in efficacy and tolerability observed in clinical practice. The authors synthesise evidence around key genetic loci, including GLP1R, GIPR, ARRB1, TCF7L2, and MC4R, and highlight a purported April 2026 genome-wide association study (GWAS) conducted by 23andMe (n=27,885) as the largest pharmacogenomic study of GLP-1 therapies to date. The review also surveys the competitive landscape among Novo Nordisk, Eli Lilly, 23andMe Research Institute, and PGxAI, and dedicates substantial attention to South Asian and Indian populations, arguing that their large diabetes burden and undercharacterised pharmacogenomic profiles represent a critical gap. The authors conclude that GLP-1 pharmacogenomics has advanced from exploratory science toward actionable clinical discovery. Limitations include the narrative (non-systematic) design, reliance on a preprint-stage GWAS of uncertain peer-review status, and the absence of prospective clinical validation data for genotype-guided prescribing.
Unknown journal · Apr 2026DOI ↗ Insufficient
This study investigated compounded semaglutide and tirzepatide products being sold by compounding pharmacies following the resolution of the innovator drug shortage. Researchers conducted a Google-based search of compounding pharmacy websites between February and March 2025, identifying 33 unique compounded GLP-1 products. Two-thirds contained semaglutide and one-third contained tirzepatide. Nearly half of the products combined the active GLP-1 ingredient with additional agents such as cyanocobalamin, glycine, niacinamide, docusate, or ondansetron. Single-ingredient products were predominantly offered in sublingual (82%) or oral disintegrating tablet (ODT) (18%) formulations. The study found that the vast majority of products lacked transparency around beyond-use dating and storage conditions. The authors concluded there was little scientific justification for adding nutrients or docusate sodium to these formulations; while ondansetron co-formulation had a theoretical rationale, evidence for subcutaneous delivery was absent. Sublingual and ODT formats also lacked comparative evidence against FDA-approved oral tablets. A key limitation is that this was an observational web survey, not a clinical study, so no safety or efficacy data on patients were collected or analyzed.
The Annals of pharmacotherapy · Feb 2026DOI ↗ Insufficient
This systematic review surveyed ClinicalTrials.gov (from inception through July 2025) to map the landscape of registered clinical trials investigating glucagon-like peptide-1 receptor agonists (GLP-1RAs) as potential treatments for substance use disorders (SUDs). Of 192 records identified, 33 trials met inclusion criteria. The most commonly studied SUD was alcohol use disorder (15 trials), followed by nicotine/tobacco (9), cocaine (4), opioid (4), and methamphetamine (1); no trials targeting cannabis use disorder were identified. Agents under investigation included semaglutide, exenatide, tirzepatide, liraglutide, dulaglutide, and pemvidutide. The review found that trial designs and outcome measures were highly heterogeneous, often blending self-reported measures (e.g., Timeline Follow-Back, craving scales) with objective indices (e.g., urine toxicology). The authors note that most registered trials rely on older-generation GLP-1RAs and that significant gaps exist for methamphetamine and cannabis use disorders. As a registry-based systematic review, it does not report clinical efficacy data from completed trials. The authors conclude that next-generation GLP-1RAs and trials using FDA-recommended endpoints are needed to establish efficacy and safety across the full spectrum of SUDs.
Addictive behaviors reports · Jan 2026DOI ↗ Insufficient
This cross-sectional pilot study examined the direct-to-consumer market for compounded glucagon-like peptide-1 (GLP-1) receptor agonists in Colorado. Researchers conducted Google searches of business websites advertising compounded GLP-1 products for weight loss across census-defined statistical areas between March and April 2024. They identified 93 websites corresponding to 188 physical locations. Most businesses were categorized as medical/health spas or weight loss services. Semaglutide was the most commonly advertised product (92/93 sites), followed by tirzepatide (40/93). Some sites advertised combination formulations including B vitamins, BPC-157 (flagged by the FDA as unsafe for compounding), and other additives. Seven sites advertised oral formulations. Notably, 41 of 93 websites referenced FDA approval in their product descriptions—a potentially misleading claim, as compounded products are not FDA-approved—and 5 sites incorrectly referred to products as "generic." The study's limitations include its focus on a single state, reliance on publicly available website data, and its pilot/cross-sectional design, which limits generalizability. The authors conclude that regulatory action is needed to address misleading advertising and safety concerns in this market.
Journal of pharmaceutical policy and practice · Dec 2024DOI ↗