Absence of exacerbation of myocardial stunning in anesthetized dogs treated with KAD-1229, a novel hypoglycemic agent

Mitiglinide, a Novel Oral Hypoglycemic Agent, Preserves the Cardioprotective Effect of Ischemic Preconditioning in Isolated Perfused Rat Hearts

Diabetic patients often have manifestation of coronary heart disease. As a consequence, therapeutic strategies for diabetes should pay more attention to hypoglycemic agents which do not have adverse effects on myocardium. Mitiglinide is considered to have little or no impact on the cardioprotective effect of ischemic preconditioning (IP) because of its high selectivity for blocking sulfonylurea receptor1 (SUR1). However, glibenclamide, a nonselective SUR blocker, attenuates this beneficial effect. In the present study, we tested the hypothesis that mitiglinide preserves the protective action of IP evaluated by ischemia/reperfusion ventricular tachyarrhythmia (rVT) in isolated perfused rat hearts. After initial perfusion, the hearts were assigned to one of the following groups: 1) non-IP with control perfusion buffer (non-IP group); 2) IP with control perfusion buffer (IP-C group); 3) IP with perfusion buffer containing glibenclamide (IP-G group); and 4) IP with perfusion buffer containing mitiglinide (IP-M group). The protocol for the non-IP group consisted of 21 minutes of aerobic perfusion before 10 minutes of ischemia. In the other 3 groups (IP groups), there were 3 cycles of 2-minute ischemia followed by 5 minutes of reperfusion before 10 minutes of ischemia. The IP-C group had a significantly shorter rVT duration than the non-IP group (4.4 +/- 1.8 minutes versus 14.3 +/- 2.5 minutes; P < 0.05). rVT duration was the shortest in the IP-M group (3.9 +/- 1.0 minutes), but among the longest in the IP-G group (14.0 +/- 2.6 minutes). In conclusion, mitiglinide preserved the cardioprotective effect of IP, however, glibenclamide abolished this beneficial effect. Therefore, mitiglinide may offer a long-term benefit for myocardial ischemia in diabetic patients.

Effects of mitiglinide and sulfonylureas in isolated canine coronary arteries and perfused rat hearts

Our aim was to compare the cardiovascular effects of mitiglinide ((+)-monocalcium bis[(2S,3a,7a-cis)-alpha-benzylhexahydro-gamma-oxo-2-isoindolinebutyrate] dehydrate), a novel hypoglycemic drug, with those of glibenclamide and glimepiride, two sulfonylurea drugs. In isolated canine coronary arteries (organ-bath method), mitiglinide, glibenclamide, and glimepiride competitively antagonized the cromakalim-induced relaxation (pA2 values, 5.29, 7.36, and 7.49, respectively). In isolated perfused rat hearts (Langendorff method) subjected to a 12-min global ischemia followed by a 30-min reperfusion, mitiglinide (3 x 10(-6) mol/l) altered neither the change in coronary perfusion flow nor the alterations in cardiac functions associated with reperfusion. In contrast, both glibenclamide (3 x 10(-8) mol/l) and glimepiride (1 x 10(-7) mol/l) significantly reduced coronary perfusion flow after reperfusion. Moreover, at 30 min of reperfusion: (1) glibenclamide induced a significant increase in left ventricular end-diastolic pressure and significant decreases in left ventricular systolic pressure, left ventricular developed pressure, and the maximum first derivative of left ventricular pressure, while (2) glimepiride induced significant decreases in left ventricular developed pressure and the maximum first derivative of left ventricular pressure. Thus, the cardiovascular effects of mitiglinide (at least, in these rat and dog preparations) may be weaker than those of glibenclamide and glimepiride.

[Pharmacological and clinical profile of mitiglinide calcium hydrate (Glufast), a new insulinotropic agent with rapid onset]

Mitiglinide calcium hydrate (mitiglinide, Glufast) is a new insulinotropic agent of the glinide class with rapid onset. Mitiglinide is thought to stimulate insulin secretion by closing the ATP-sensitive K(+) (K(ATP)) channels in pancreatic beta-cells, and its early insulin release and short duration of action would be effective in improving postprandial hyperglycemia. In studies of various cloned K(ATP) channels, mitiglinide shows a higher selectivity for the beta-cell type of SUR1/Kir6.2 than the cardiac and smooth muscle types of K(ATP) channels in comparison with glibenclamide and glimepiride. In vitro and in vivo studies demonstrated the insulinotropic effect of mitiglinide is more potent than that of nateglinide, and mitiglinide surpassed in controlling postprandial hyperglycemia in normal and diabetic animals. In clinical trials, treatment with mitiglinide provided lasting improvement of postprandial hyperglycemia in Type 2 diabetic patients and decreased the fasting plasma glucose levels and HbA(1C) values. The incidence of adverse events related to mitiglinide were nearly equivalent to placebo; in particular there was no difference with the frequency of hypoglycemia. The results from these studies indicated that mitiglinide could be expected to possess good therapeutic features of being effective in reducing postprandial glucose excursions in the early stage of Type 2 diabetes and less incidence of events suggestive of hypoglycemia.