System suitability determines whether an HPLC system and method are performing adequately at the time of a peptide analysis. Learn what repeatability, resolution, peak shape, and theoretical plates demonstrate—and what they cannot prove.
TLDR A paper can be technically accurate and still be easy to misread. Suppose the headline says: “Peptide X reduced tumor growth by 60%.” That sounds impressive. But before deciding what it means, we need to know whether the experiment involved: a purified enzyme, a dish of cancer cells, a mouse xenograft, twenty patients, or … Read more
Glucagon has traditionally been associated with one thing: raising blood glucose. So it can sound counterintuitive that retatrutide, a molecule being studied for obesity and type 2 diabetes, was deliberately designed to activate the glucagon receptor. That receptor activity is not an accidental side effect. It is one of the defining features of retatrutide. Retatrutide, … Read more
Peptide photostability depends on sequence, formulation, oxygen, light spectrum, exposure, and packaging. Learn what light-stress studies can—and cannot—establish.
TLDR Retatrutide has now produced significant improvements in both glycemic control and body weight in peer-reviewed Phase 2 and Phase 3 trials involving people with type 2 diabetes. The 2023 Phase 2 study found A1C reductions of about 2 percentage points at the higher doses and weight loss approaching 17% after 36 weeks. The evidence … Read more
TLDR A peptide can have the correct sequence when it is synthesized and still become a chemically different material later. Sometimes a bond breaks. Sometimes an amino acid side chain is oxidized. Sometimes an asparagine residue rearranges. And sometimes the peptide remains chemically unchanged but begins associating with other peptide molecules until aggregates or fibrils … Read more
A high HPLC purity result can coexist with lower peptide content because chromatographic purity, target-peptide mass, and total material mass are different measurements.
Synthetic peptides are often isolated as salts containing TFA, acetate, chloride, or another counterion. This guide explains why salt form matters, why weighed material is not necessarily peptide-only mass, and which lot-specific measurements clarify composition.
Updated September 4, 2026 Retatrutide is no longer a drug candidate supported by one or two promising trials. Eli Lilly has built a broad clinical development program around the investigational triple hormone receptor agonist, testing it across obesity, type 2 diabetes, cardiovascular disease, chronic kidney disease, obstructive sleep apnea, knee osteoarthritis, chronic low back pain, … Read more
Peptide solubility reflects a system-specific balance among hydration, ionization, self-association and solid-state interactions. This guide explains why sequence, pH, concentration, salts, solvents and temperature must be considered together.
TLDR Semaglutide is a peptide. So is retatrutide. So are insulin, glucagon, liraglutide, teriparatide, oxytocin, and many other biologically active molecules. But saying that two products “contain peptides” tells us very little about their regulatory or pharmaceutical status. A research peptide sold as a laboratory reagent and an FDA-approved peptide medicine may even contain nominally … Read more
Retatrutide’s Phase 3 results are now large enough that one number no longer describes the drug. Depending on which trial you look at, the highest-dose retatrutide group lost an average of about 20.8%, 22.6%, 28.3%, or 28.7% of body weight. Those differences are not contradictions. They come from four trials that studied very different people. … Read more
Retatrutide has now been studied in thousands of people across Phase 2 and Phase 3 clinical trials. That gives researchers a much clearer picture of its safety profile than was available when the first obesity results appeared in 2023. The most consistent finding is not surprising: gastrointestinal side effects are the most common adverse events, … Read more
TLDR A peptide stability study is really a study of change. Researchers begin with a characterized peptide and repeatedly ask the same question: Is it still the same material? That sounds simple until we define what “same” means. A peptide could retain 99% chromatographic purity while forming a small amount of aggregate. It could maintain … Read more
Large reductions in body weight almost never come entirely from body fat. Some fat-free mass is usually lost as well. That has made muscle loss an important question for newer incretin-based drugs, especially retatrutide, which has produced particularly large weight reductions in clinical trials. The good news is that researchers now have direct body-composition data … Read more
