the racemic material, except that the intermediate aldehyde in the sequence (exogonal) was oxidized to the acid by a different proced~re.~~ Methylation (CH2N2) then provided methyl exogonate as the 2R,5R,7S E,E and 2R,5S,7S Z,Z stereoisomers, -4.3O (c 5.05, CHC13). The methyl ester of purified natural exogonic acid exhibited [a]"OD +7.6O. The 'H and 13C NMR spectra and GC-MS data of this synthesized methyl exogonate were identical with those previously reported.6 13C NMR (CDCI,):

The aim of present study was to develop stomach specific floating beads of metformin hydrochloride for effective management of type 2 diabetes mellitus. The beads were evaluated for surface morphology, particle size, tapped density, true density, percent porosity, drug entrapment efficiency, percent yield, differential scanning calorimetry, in vitro floating ability and in vitro drug release. Stability studies were performed at 25 and 40 °C up to 45 days. Effectiveness of the formulations was evaluated in vivo by hypoglycemic response in both normal and diabetic albino rats. The beads were grossly spherical in shape, and average particle diameter of beads was found to be in the size range of 861.34 to 991.75 μm. Percent entrapment was found to be in the range of 77.61 to 82.48%. Beads demonstrated favorable in vitro floating ability. All the formulations followed a non-Fickian release mechanism. It was found that there was no significant effect on floating ability of aged beads since it floated up to an 8 h study period. In vivo studies on diabetic rats showed that the hypoglycemic effect induced by the metformin hydrochloride loaded alginate beads was significantly greater (P < 0.05) and more prolonged than that induced by the nonfloating beads. The results clearly demonstrated the ability of the formulation to maintain blood glucose level and improved the patient compliance by enhancing, controlling and prolonging the systemic absorption of metformin hydrochloride.

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Ausgehend vom 6‐lithiierten 2‐Brompyridin wird durch Cu‐induzierte Dimerisierung bei ‐100°C das Bipyridyl (I) erhalten (Ausb. 60%), das mit den Di‐Na‐Derivaten der Glykole (II) in siedendem Xylol die Kronenether (III) und (IV) liefert, wobei die Ausb. mit steigender Ringgröße zunehmen.

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