aThe cocrystal formation of the anticonvulsant drug carbamazepine (CBZ) with para-aminosalicylic acid (PASA, antituberculous drug) has been studied by varying the molar ratios of CBZ to PASA (1 : 1 and 2 : 1) and using liquid-assisted grinding (LAG), slurrying and solution crystallization methods. PASA has been shown to lead to a dramatic decrease of the CBZ rate of conversion from the anhydrous to the hydrate form, and as a consequence, to solubility improvement by approximately 1.5 times.