title: Thermodynamic Solubility Profile of Carbamazepine-Cinnamic Acid Cocrystal at Different pH.
abstract: Pharmaceutical cocrystal formation is a direct way to dramatically influence physicochemical properties of drug substances, especially their solubility and dissolution rate. Because of their instability in the solution, thermodynamic solubility of cocrystals could not be determined in the common way like other compounds; therefore, the thermodynamic solubility is calculated through concentration of their components in the eutectic point. The objective of this study is to investigate the effect of an ionizable coformer in cocrystal with a nonionizable drug at different pH. Carbamazepine (CBZ), a nonionizable drug with cinnamic acid (CIN), which is an acidic coformer, was selected to prepare CBZ-CIN cocrystal and its thermodynamic solubility was studied in pH range 2-7. Instead of HPLC that is a costly and time-consuming method, a chemometric-based approach, net analyte signal standard addition method, was selected for simultaneous determination of CBZ and CIN in solution. The result showed that, as pH increases, CIN ionization leads to change in CBZ-CIN cocrystal solubility and stability in solution. In addition, the results of this study indicated that there is no significant difference between intrinsic solubility of CBZ and cocrystal despite the higher ideal solubility of cocrystal. This verifies that ideal solubility is not good parameter to predict cocrystal solubility.
authors.affiliation: Liver and Gastrointestinal Diseases Research Center and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.|Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Keramatnia
authors.affiliation: Drug Applied Research Center and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Shayanfar
authors.affiliation: Drug Applied Research Center and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Abolghasem
authors.initials: A
authors.lastname: Jouyban
mesh_terms: D000465:Algorithms; D000927:Anticonvulsants / Q000737:chemistry*; D002220:Carbamazepine / Q000737:chemistry*; D055598:Chemical Phenomena; D002934:Cinnamates / Q000737:chemistry*; D004339:Drug Compounding; D004355:Drug Stability; D005079:Excipients / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D048088:Informatics; D007700:Kinetics; D008956:Models, Chemical; D011208:Powders; D015203:Reproducibility of Results; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
chemical_list: D000927:Anticonvulsants; D002934:Cinnamates; D005079:Excipients; D011208:Powders; C029010:cinnamic acid; D002220:Carbamazepine
keywords: co-crystal; crystal engineering; pH; solubility; stability; thermodynamic