Proanthocyanidin and anthocyanins from the hulls and beards of red-kerneled rice and their antiglycation properties.

In the current study, we isolated a proanthocyanidin oligomer from the hulls of red-kerneled rice. The structure of the oligomer was characterized based on spectral data and chemical reaction. Furthermore, two anthocyanins were isolated from the beards of the same source. The proanthocyanidins and beard extract showed more potent inhibitory and cleaving activities than those of positive controls, respectively.

In vitro-in vivo correlation for wet-milled tablet of poorly water-soluble cilostazol.

The purpose of the present study was to investigate oral bioavailability of an immediate release tablet containing wet-milled crystals of a poorly water-soluble drug, cilostazol, and to establish in vitro-in vivo correlation. Sub-micron sized cilostazol (median diameter: 0.26 microm) was successfully prepared using a beads-mill in water in the presence of a hydrophilic polymer and an anionic surfactant. The milled suspension was solidified with a sugar alcohol as a water-soluble carrier by spray-drying method. The co-precipitate was compressed into an immediate release tablet with common excipients. Oral bioavailability of the wet-milled cilostazol tablet in male beagle dogs was 13-fold higher than the hammer-milled commercial tablet in fasted condition. Food did not increase the oral bioavailability of the wet-milled tablet, while 4-fold increase was found for the commercial tablet. Irrespective to the bioavailability enhancement, in vitro dissolution rate of the wet-milled tablet was even slower than the commercial tablet by the compendial method (USP Apparatus 2). On the other hand, a good correlation was found between the dissolution profiles obtained by a flow-through cell method (USP Apparatus 4, closed-loop system without outlet filter) using a large volume of water and sodium lauryl sulfate (SLS) solution at the concentration lower than the critical micellar concentration (cmc) as dissolution media corresponding to the fasted and fed conditions, respectively.

Development of suppository formulation safely improving rectal absorption of rebamipide, a poorly absorbable drug, by utilizing sodium laurate and taurine.

To develop the safe formulation that can safely improve bioavailability of poorly absorbable drugs and that is practically available, we prepared the suppositories of rebamipide, a poorly soluble and poorly absorbable antiulcer drug, by employing the combinatorial use of sodium laurate (C12), an absorption enhancer, with taurine (Tau) or L-glutamine (L-Gln), an adjuvant exerting the cytoprotective action. Although the dissolution of rebamipide from fatty base (FB) suppository prepared using Witepsol H-15 was very slow, it was remarkably improved by the addition of C12 and L-Gln or Tau into the suppository. On the other hand, the dissolution of rebamipide from water-soluble base (WB) suppository prepared using polyethylene glycol was very rapid and the addition of adjuvants did not influence its dissolution so much. Rectal absorption of rebamipide examined in rats was remarkably improved by FB suppository containing C12 or both C12 and Tau, while the enhancing effect of C12 was relatively small in the case of WB suppositories. Biochemical and histopathological studies have confirmed that FB suppository containing both C12 and Tau or L-Gln did not cause any serious local damage, while FB suppository containing C12 only caused the erosion and shrinkage for a lot of rectal epithelial cells. In conclusion, FB suppository employing the combinatorial use of C12 with Tau could be a promising formulation that is effective and safe enough for poorly absorbable drugs to be practically administered.

Combinatorial use of sodium laurate with taurine or L-glutamine enhances colonic absorption of rebamipide, poorly absorbable antiulcer drug, without any serious histopathological mucosal damages.

We previously reported that the combinatorial use of sodium laurate (C12) with several amino acids such as taurine (Tau) and L-glutamine (L-Gln) enhanced the colonic absorption of phenol red with attenuating the local toxicity caused by C12. However, even these amino acids could not protect epithelial cells from being damaged if the mucosal damage got worse to the coagulation necrosis by an excessive dose of C12. Comparing C12 with sodium caprate (C10), used in drug products marketed, 100 micromol C10 was needed to exert the similar absorption-enhancement of rebamipide, a poorly absorbable antiulcer drug, to that by 10 micromol C12, and 100 micromol C10 was obviously more toxic to the mucosa than 10 micromol C12. The combinatorial use of C12 with Tau or L-Gln enhanced the colonic absorption of rebamipide four to nine times larger in AUC than the control. Histopathologic studies clearly showed that Tau and L-Gln exerted the cytoprotective action on epithelial cells suffering from slight damages such as shrinkage and exfoliation, more articulately at 6 h than at 1.5 h after dosing. In conclusion, the combinatorial use of C12 with Tau or L-Gln could lead to a novel formulation improving the bioavailability of poorly absorbable drugs without any serious local damages.