Unusual solubility and dissolution behavior of pharmaceutical hydrochloride salts in chloride-containing media
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説明
Abstract The pH-solubility profiles of 3 pharmaceutical hydrochloride salts were determined in sodium acetate-hydrochloric acid buffer. Unusual pH-solubility profiles containing maxima at pH 4–6 were observed for phenazopyridine hydrochloride, cyproheptadine hydrochloride and bromhexine hydrochloride. The decrease in solubility at lower pH values was attributed to the common ion effect of chloride on the solubility product equilibrium of the hydrochloride salts. The dissolution behavior of the free bases and that of the hydrochloride salts of these drugs were compared in dilute hydrochloric acid solution, in pH range from 1.0 to 3.0. The apparent dissolution rates and solubilities of these hydrochlorides were less than those of the respective free base forms in the pH range of the stomach (pH 1.0–2.0). These results substantiated further the contention that the salt formation does not always result in an enhancement of solubility characteristics.
収録刊行物
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- International Journal of Pharmaceutics
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International Journal of Pharmaceutics 6 77-85, 1980-07-01
Elsevier BV