It is expected that co-crystals of drug substances with different pharmaceutical properties and medical activities will be characterized by a wider spectrum of activity, new therapeutic properties and better bioavailability of the drug .
Although fenamic acids are very popular non-steroidal anti-inflammatory substances  used in therapy, their physical properties as solubility in water connected to the pharmaceutical dosage needs to be improved.
Ethacridine lactate is a drug used as an antiseptic agent therefore it can be expected that co-crystals of ethacridine with fenamic acids will combine pharmaceutical properties of both components and additionally will be characterized by improved bioavailability.
Organic complexes of fenamic acids (fenamic, mefenamic, flufenamic, tolfenamic)
and ethacridine have been obtained by formation of the network of intermolecular of N–H∙∙∙O and C–H∙∙∙O hydrogen bonds, occurring between the components of the co-crystal, as well as O–H∙∙∙O and N–H∙∙∙O hydrogen bonds generated by fenamate and ethacridine species along with water molecules. The crystal structure of fenamic acids with ethacridine will be presented and analysis of the hydrogen bonds will be performed.
Finacial support: Grant of the Wrocław Medical University STM.D050.17.002.
Figure. Structure of co-crystal of mefenamic acid with ethacridine.