The efficacy of the combination of the rapid-acting insulin secretagogue mitiglinide and the sodium-glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin was explored in streptozotocin-nicotinamide-induced type 2 diabetic (STZ-NA) rats and in Zucker fatty (ZF) rats. The STZ-NA rats were prepared at 8 weeks of age. At 9 weeks of age, the combination study was conducted by oral glucose tolerance test (OGTT). At 13 weeks of age, ZF rats were dosed orally with dapagliflozin once daily up to the 22(nd) day. At days 15 and 22, the combination study was conducted by OGTT. In 2 different animal models, plasma glucose levels were strongly suppressed by the combination of mitiglinide and dapagliflozin as compared with either drug alone. The urinary glucose excretion was drastically elevated in the dapagliflozin group, but the combination with mitiglinide suppressed it about 50%. In STZ-NA rats, the plasma insulin secretion by the combination of both drugs was about at the same level as in the mitiglinide group. In ZF rats, the plasma insulin secretion by the combination of both drugs was less than mitiglinide group. Thus, in 2 different animal models, the combination of mitiglinide and dapagliflozin showed stronger antihyperglycemic action accompanied by less insulin secretion than mitiglinide alone, and reduced the urinary glucose excretion as compared with dapagliflozin used alone. These results indicate that the combination of mitiglinide and dapagliflozin can be a promising combination for the treatment of diabetic patients.

The effects of PA21, a novel iron-based and non-calcium-based phosphate binder, on hyperphosphatemia and its accompanying bone abnormality in chronic kidney disease-mineral and bone disorder (CKD-MBD) were evaluated. Rats with adenine-induced chronic renal failure (CRF) were prepared by feeding them an adenine-containing diet for four weeks. They were also freely fed a diet that contained PA21 (0.5, 1.5, and 5%), sevelamer hydrochloride (0.6 and 2%) or lanthanum carbonate hydrate (0.6 and 2%) for four weeks. Blood biochemical parameters were measured and bone histomorphometry was performed for femurs, which were isolated after drug treatment. Serum phosphorus and parathyroid hormone (PTH) levels were higher in the CRF rats. Administration of phosphate binders for four weeks decreased serum phosphorus and PTH levels in a dose-dependent manner and there were significant decreases in the AUC0–28 day of these parameters in 5% PA21, 2% sevelamer hydrochloride, and 2% lanthanum carbonate hydrate groups compared with that in the CRF control group. Moreover, osteoid volume improved significantly in 5% of the PA21 group, and fibrosis volume and cortical porosity were ameliorated in 5% PA21, 2% sevelamer hydrochloride, and 2% lanthanum carbonate hydrate groups. These results suggest that PA21 is effective against hyperphosphatemia, secondary hyperparathyroidism, and bone abnormalities in CKD-MBD as sevelamer hydrochloride and lanthanum carbonate hydrate are, and that PA21 is a new potential alternative to phosphate binders.

BackgroundApproximately 30% of patients on dialysis received combination therapy for their phosphate binder prescription; however, few studies for combined effects of phosphate binders are reported. For the purpose of evaluating the efficacy of combination therapy, we compared the efficacy of sucroferric oxyhydroxide (PA21) combined with calcium carbonate with that of lanthanum carbonate hydrate, sevelamer hydrochloride, and ferric citrate hydrate combined with calcium carbonate.MethodsFor in vitro studies, calcium carbonate and the other phosphate binders alone or in combination were stirred in phosphate solution at pH 2–8 for 2 h. After centrifuging the suspension, the phosphorus level in the supernatant was determined. For in vivo studies, rats were orally administered calcium carbonate and the other phosphate binders (except for sevelamer hydrochloride) alone or in combination, followed by oral administration of phosphate solution adjusted to pH 2 or 7. Serum samples were collected from the rats at predetermined timepoints and the serum phosphorus levels were determined and analyzed using a two-way analysis of variance.ResultsIn the in vitro study, the measured phosphate-binding capacity of combining sevelamer hydrochloride, PA21, and lanthanum carbonate hydrate with calcium carbonate was approximately equal to or greater than the theoretical values under most conditions. Furthermore, these combined effects were insensitive to pH in that order. The measured phosphate-binding capacity of ferric citrate hydrate combined with calcium carbonate was smaller than the theoretical values, and the combination did not exhibit efficacy under any of the tested conditions. In the in vivo study, the combined effect of PA21 and calcium carbonate at both pH values and that of lanthanum carbonate hydrate and calcium carbonate at pH 2 were additive. In contrast, the combined effect of lanthanum carbonate hydrate and calcium carbonate at pH 7 and that of ferric citrate hydrate and calcium carbonate at pH 2 were antagonistic.ConclusionsThese results suggest that coadministration of PA21 and calcium carbonate showed good and relatively stable efficacy throughout the range of the gastrointestinal pH and that combining lanthanum carbonate hydrate and ferric citrate hydrate with calcium carbonate may not produce the expected efficacy under certain conditions.

These results indicated that PA21 has a phosphate binding capacity over the entire pH range of the GI tract.

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