Stabilization study on a wet-granule tableting method for a compression-sensitive benzodiazepine receptor agonist.

SX-3228, 6-benzyl-3-(5-methoxy-1,3,4-oxadiazol-2-yl)-5,6,7,8-tetrahydro-1,6-naphthyridin-2(1H)-one, is a newly-synthesized benzodiazepine receptor agonist intended to be developed as a tablet preparation. This compound, however, becomes chemically unstable due to decreased crystallinity when it undergoes mechanical treatments such as grinding and compression. A wet-granule tableting method, where wet granules are compressed before being dried, was therefore investigated as it has the advantage of producing tablets of sufficient hardness at quite low compression pressures. The results of the stability testing showed that the drug substance was chemically considerably more stable in wet-granule compression tablets compared to conventional tablets. Furthermore, the drug substance was found to be relatively chemically stable in wet-granule compression tablets even when high compression pressure was used and the effect of this pressure was small. After investigating the reason for this excellent stability, it became evident that near-isotropic pressure was exerted on the crystals of the drug substance because almost all the empty spaces in the tablets were occupied with water during the wet-granule compression process. Decreases in crystallinity of the drug substance were thus small, making the drug substance chemically stable in the wet-granule compression tablets. We believe that this novel approach could be useful for many other compounds that are destabilized by mechanical treatments.

Stabilization by meglumine of an amine compound degraded by formaldehyde in tablets.

[3-[(2R)-[[(2R)-(3-Chlorophenyl)-2-hydroxyethyl]amino]proryl]-1H-indol-7-yloxy]acetic acid (AJ-9677), which was being developed as an antidiabetic, was observed to degrade in tablet preparations. The main degradation product in tablets, AD-9889, was a carbon adduct of the drug substance. When the drug substance was exposed to formaldehyde in aqueous solutions, a correlation was found between the level of formaldehyde and the quantity of AD-9889 formed during storage. Comprehensive one- and two-dimensional NMR analysis of the reaction product identified the location of the carbon atom which originated from formaldehyde, thus proving that AD-9889 was produced by a reaction with formaldehyde. Since it was demonstrated in our previous report that meglumine is an amine that can react with, and reduce amounts of formaldehyde, its stabilizing effect on AJ-9677 was examined. The results showed that in a solution system containing AJ-9677, formaldehyde and meglumine, meglumine reduced formaldehyde levels and suppressed degradation. Addition of meglumine into the tablet formulation of AJ-9677 was also effective in suppressing degradation and successfully stabilized the drug substance. This effect was almost certainly due to meglumine absorbing formaldehyde from around the drug substance and we believe that meglumine can be used with many other drug substances degraded by formaldehyde.