Study summary · research use only
Stability of peptide drugs in the colon
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
In this study, the authors investigated the colonic stability of 17 peptide molecules (including insulin, calcitonin, glucagon, secretin, somatostatin, desmopressin, oxytocin, Arg-vasopressin, octreotide, ciclosporin, leuprolide, nafarelin, buserelin, histrelin, [D-Ser(4)]-gonadorelin, deslorelin, and goserelin) using a large-intestine model with mixed human faecal bacteria. The abstract reports that the larger peptides, insulin, calcitonin, somatostatin, glucagon and secretin, were metabolized rapidly, with complete degradation within 5 min, while several smaller peptides degraded more slowly, and octreotide, histrelin and ciclosporin were more stable. It states degradation rate correlated with peptide lipophilicity (higher logP more stable; R2=0.94), and that all peptides were stable without faecal bacteria.
Abstract
This study was the first to investigate the colonic stability of 17 peptide molecules (insulin, calcitonin, glucagon, secretin, somatostatin, desmopressin, oxytocin, Arg-vasopressin, octreotide, ciclosporin, leuprolide, nafarelin, buserelin, histrelin, [D-Ser(4)]-gonadorelin, deslorelin, and goserelin) in a model of the large intestine using mixed human faecal bacteria. Of these, the larger peptides - insulin, calcitonin, somatostatin, glucagon and secretin - were metabolized rapidly, with complete degradation observed within 5 min. In contrast, a number of the smaller peptides - Arg-vasopressin, desmopressin, oxytocin, gonadorelin, goserelin, buserelin, leuprolide, nafarelin and deslorelin - degraded more slowly, while octreotide, histrelin and ciclosporin were seen to be more stable as compared to the other small peptides under the same conditions. Peptide degradation rate was directly correlated to peptide lipophilicity (logP); those peptides with a higher logP were more stable in the colonic model (R(2)=0.94). In the absence of human faecal bacteria, all peptides were stable. This study highlights the impact of the colonic environment - in particular, the gut microbiota - on the metabolism of peptide drugs, and identifies potential peptide candidates for drug delivery to the colon.
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