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Ampicillin-polyvinylpyrrolidone coprcipitates, 1 : 5 ratio w/w, were prepared by the solvent method to increase the solubility and dissolution rate of ampicillin anhydrous. It was found that the solubility and dissolution rate of the coprecipitate were higher than that of ampicillin anhydrous, mechanical mixture of ampicillin and polyvinylpyrrolidone in powder state. The intrinsic, dissolution rate, G, are 1.15×10?4molecm?2min?1 for the coprecipitate, 1.09×10?5molecm?2min?1 for ampicillin anhydrous, and the activation energy of the coprecipitate and ampicillin anhydrous are 9.091×103cal/mole and 1.854×103cal/mole, respectively.
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