Our previous studies
revealed that the kc and Kc values in the SBE4-β-CyD system were 0.145 ± 0.012h−1 and 144 ± 18M−1, respectively . Therefore, it is evident that the inhibitory effect of SBE7-β-CyD on enzymatic degradation of insulin glargine is more potent than that of SBE4-β-CyD. Figure 6 Effects of Sul-β-CyD and SBE7-β-CyD (5 to 20mM) on tryptic cleavage (2IU) of insulin glargine (0.1mM) in phosphate buffer (pH 9.5, I = 0.2) at 37°C. Each point represents Inhibitors,research,lifescience,medical the mean ± S.E.M. of … Recently, it has been reported that the aspartic acid residue existing in the catalytic pocket of trypsin is responsible for attracting and stabilizing positively charged lysine and/or arginine on the substrate Inhibitors,research,lifescience,medical peptide . Therefore, the insulin glargine/Sul-β-CyD interaction or insulin glargine/SBE7-β-CyD complex is speculated to ameliorate the interaction between the negatively charged aspartic acid in the catalytic pocket of trypsin and positively charged lysine and/or arginines mentioned earlier, since Sul-β-CyD and SBE7-β-CyD have negative charge originating from the sulfate and sulfonate Inhibitors,research,lifescience,medical groups, respectively.
This hypothesis in which the insulin glargine/Sul-β-CyD interaction and insulin glargine/SBE7-β-CyD complex ameliorate the interaction between the aspartic acid and lysine and/or arginines is supported by the finding that the aromatic amino acid residues in insulin glargine which are capable of
interacting with β-CyDs (at B24-, B25-phenylalanines, B26-tyrosine, Inhibitors,research,lifescience,medical and B28-proline) locate near the three digestive sites by trypsin (B22-B23, B29-B30, and B31-B32) . These results suggest that Sul-β-CyD and SBE7-β-CyD act as stabilizers of insulin glargine NVP-AUY922 solubility dmso against Inhibitors,research,lifescience,medical enzymatic degradation by their respective interactions with insulin glargine. 3.7. Subcutaneous Administration of Insulin Glargine/β-CyDs Solutions to Rats To confirm whether Sul-β-CyD and SBE7-β-CyD are useful excipients for insulin glargine in vivo, we evaluated the effects of the β-CyDs on pharmacokinetics and pharmacodynamics of insulin glargine after subcutaneous injection to rats. In our preliminary studies, we found heptaminol that neither Sul-β-CyD (100mM) nor SBE7-β-CyD (100mM) changed the serum glucose level-time profiles remarkably in comparison with that of insulin glargine alone (2IU/kg) after subcutaneous injection to rats (data not shown). Taking the positive results of SBE7-β-CyD in ultrafiltration (Figure 2) and dissolution (Figure 3) studies by contrast to those of Sul-β-CyD into account, further in vivo investigation was performed with a higher concentration of SBE7-β-CyD.