Dissolution Kinetics of a Weak Acid, 1,1-hexamethylene p-Tolylsulfonylsemicarbazide, and Its Sodium Salt

Miniaturized Approach for Excipient Selection During the Development of Oral Solid Dosage Form

“…As evident from Figure , comparison of the dissolution profiles for NS and NFA reveals negligible difference in dissolved amounts of both forms at pH 2, whereas the dissolved amount of NS was found to be significantly higher than that of NFA at pH 5.5 and 6.8. This phenomenon can be explained on the basis of the same mechanism proposed by Higuchi et al for a weak acid, tolazamide, and its sodium salt. Accordingly, at low pH values (at pH 2 in this case), there is formation of an “acid coat” surrounding the dissolving particles because of the immediate disproportionation of the salt form.…”

“…The concept of microenvironment pH has been used in many literature reports to explain dissolution behavior of pharmaceutical salts . As evident from Figure , comparison of the dissolution profiles for NS and NFA reveals negligible difference in dissolved amounts of both forms at pH 2, whereas the dissolved amount of NS was found to be significantly higher than that of NFA at pH 5.5 and 6.8.…”

Isoenergetic Polymorphism: The Puzzle of Tolazamide as a Case Study

“….2186(9)9.0679(6)13.8712 (7) c [] 13.5146 (13) 13.4841 (10) 11.2358(6) a [8]78.997(8)82.510 (6) 90.00 b [8]87.202 (7)85.260(5)105.163(4) g [8]85.811 (7) 85.839 (5)90.00 V [ 3 ]774.86 (12) 784.25 (9) 1572.76 (14) (V/2 = 786) Z 224 Figure 5. H-Bonded ribbonsa nd molecular packing in the crystal structures of tolazamide polymorphs: a) Form I; b) and c) Form II, and d) and e) Form III.…”

Effect of Added Alkalizer and Surfactant on Dissolution and Absorption of the Potassium Salt of a Weakly Basic Poorly Water-Soluble Drug

“…Salts of weak acids convert to the less‐soluble neutral forms during dissolution in the stomach. This in some cases causes gelling of the drug in the tablet formulation and in other cases formation of a layer of free acid or neutral form on the surface of the dosage form . As a result, the drug release from the tablet formulation is either retarded or in some cases completely hindered.…”

“…the tablet formulation and in other cases formation of a layer of free acid or neutral form on the surface of the dosage form. 4 As a result, the drug release from the tablet formulation is either retarded or in some cases completely hindered. Some of the most common approaches employed to overcome this issue are addition of surfactants, inorganic salts, disintegrants, polymers, or pH modifiers to provide a more favorable local environment for drug release, control active pharmaceutical ingredient (API) particle size, and dilution of the tablet with more excipients.…”