Safety and efficacy of an oral insulin (Capsulin) in patients with early-stage type 2 diabetes: A dose-ranging phase 2b study.

AIM: To compare the pharmacodynamic properties of different doses of regular human insulin administered in capsule form twice daily in a randomised twelve-week open-label study. METHODS: A total of 100 individuals (48 males, 52 females) with type 2 diabetes on metformin completed the study according to the protocol. The mean (SD) age was 48.5 (6.7) years, body mass index 25.7 (2.8) kg/m2 and HbA1c 8.10% (0.65%). Subjects randomized upon admission were assigned to one of three groups receiving formulated regular insulin at dose levels of 75 iu BD, 150 iu insulin BD, or 300 iu BD, all in enteric-coated capsules. The primary and secondary endpoints were change from baseline in HbA1c and fasting plasma glucose (FPG), respectively. RESULTS: The study met its primary clinical endpoint of a decrease in HbA1c of 0.5% or higher (least square mean decrease 0.52%; P = .004, median decrease 0.6%) in the dose group receiving 150 iu BD. In a subset of this population, with starting HbA1c values of 9% to 9.5%, an average decrease of 1.575% was observed. In the total population, least square mean decreases in HbA1c for the 75 and 300 iu BD groups were -0.11% and -0.42%, respectively. Mean change in FPG in the 150 iu BD dose group was -18.8 mg/dl (P = .017) and -14.8 and -2.7 mg/dl for the 75 and 300 iu BD groups, respectively. A decrease of 20% for triglycerides (-40 mg/dl) was observed in the 150 iu BD dose group. No significant increases in body weight were observed, and significant decreases in systolic blood pressure were seen in all groups. No serious treatment-related adverse events were recorded, and no incidence of hypoglycaemia was reported throughout the entire 12-week study period. CONCLUSIONS: Capsulin oral insulin administered twice per day at a dose of 150 iu per capsule is safe, with no confirmed treatment-linked hypoglycaemic events, and results in significant decreases from baseline in HbA1c, FPG and triglycerides.

Binding Interactions of Peptide Aptamers.

Peptide aptamers are short amino acid chains that are capable of binding specifically to ligands in the same way as their much larger counterparts, antibodies. Ligands of therapeutic interest that can be targeted are other peptide chains or loops located on the surface of protein receptors (e.g., GCPR), which take part in cell-to-cell communications either directly or via the intermediary of hormones or signalling molecules. To confer on aptamers the same sort of conformational rigidity that characterises an antibody binding site, aptamers are often constructed in the form of cyclic peptides, on the assumption that this will encourage stronger binding interactions than would occur if the aptamers were simply linear chains. However, no formal studies have been conducted to confirm the hypothesis that linear peptides will engage in stronger binding interactions with cyclic peptides than with other linear peptides. In this study, the interaction of a model cyclic decamer with a series of linear peptide constructs was compared with that of a linear peptide with the same sequence, showing that the cyclic configuration does confer benefits by increasing the strength of binding.

Efficacy of Bioactive Cyclic Peptides in Rheumatoid Arthritis: Translation from In Vitro to In Vivo Models.

Using a novel drug discovery technology reported in previous issues of this journal cyclic peptides have been created which are able to down-regulate secretion of inflammatory cytokines, in vitro, by stimulated cells of the macrophage cell line J774. The cytokines in question, TNF-alpha and IL-6, are strongly implicated in etiology of diseases such as rheumatoid arthritis. Studies are reported here using the CAIA animal model for rheumatoid arthritis, which show that the peptides identified are indeed able to impact on inflammation of joints, induced in vivo. The results suggest that these peptides are effective at a dose which could be viable in man, and at which no adverse side effects are evident in the short term.

Design and optimisation of bioactive cyclic peptides: generation of a down-regulator of TNF secretion.

Although strong binding interactions between protein receptor and ligand do not require the participation of a large number of amino acids in either site, short peptide chains are generally poor at recreating the types of protein-protein interactions which take place during cell recognition and signalling process, probably because their flexible backbones prevent the side chains from forming sufficiently rigid and stable epitopes, which can take part in binding with the desired strength and specificity. In a recently-reported study, it was shown that a proto-epitope containing F, R and S amino acids has the ability to down-regulate TNF secretion by macrophages. This paper extends these findings, putting those amino acids into a short cyclic peptide scaffold, and determining the optimal configuration required to overcome the problems of conformational instability, and give rise to molecules which have potential as therapeutic agents in human disease, such as rheumatoid arthritis.