Refers to a co Crystal of agomelatine, which includes: (a) to agomelatine or N - [2 - (7 - methoxy - 1-naphthyl) ethyl] acetamide of formula (i) and (b) an organic acid such as Citric Acid, oxalic acid, gallic acid, glutaric acid, among others which presents Diagram x Powder diffraction on Values Bragg Angle 2 - Theta - such as 5,21\u00ba, 12,24\u00ba, 17,07\u00ba, 19,38\u00ba, 20,69\u00ba, 21,72\u00ba, 27,36\u00ba, 29,77\u00ba,11,30\u00ba, 11,95\u00ba, 25,05\u00ba, 9,59\u00ba, 10,35\u00ba, among others.It also relates to a Pharmaceutical Composition and a preparation method comprising: (i) MIX THE 2 constituents in an organic Solvent (1 equivalent of agomelatine for 0.25 to 4 molar Equivalents of organic acid), (ii) Shake and optionally Heat temperature Boiling Point of the Solvent, (iii) Stir to cool,The cocristal precipitates and precipitates after collected in a Second Solvent, (iv) The precipitate obtained was filtered and dried. The cocristal is useful for the treatment of stress, Sleep Disorders, diabetes, Epilepsy, painSE REFIERE A UN CO-CRISTAL DE AGOMELATINA QUE COMPRENDE: A) AGOMELATINA O N-[2-(7-METOXI-1-NAFTIL)ETIL]ACETAMIDA DE FORMULA (I) Y B) UN ACIDO ORGANICO TAL COMO ACIDO CITRICO, ACIDO OXALICO, ACIDO GALICO, ACIDO GLUTARICO, ENTRE OTROS QUE PRESENTA DIAGRAMA DE DIFRACCION X SOBRE POLVO CON VALORES DE ANGULOS DE BRAGG 2 TETHA TALES COMO 5,21º, 12,24º, 17,07º, 19,38º, 20,69º, 21,72º, 27,36º, 29,77º, 11,30º, 11,95º, 25,05º, 9,59º, 10,35º, ENTRE OTROS. SE REFIERE TAMBIEN A UNA COMPOSICION FARMACEUTICA Y A UN PROCEDIMIENTO DE PREPARACION QUE COMPRENDE: i) MEZCLAR LOS 2 CONSTITUYENTES EN UN DISOLVENTE ORGANICO (1 EQUIVALENTE DE AGOMELATINA PARA 0,25 A 4 EQUIVALENTES MOLARES DE ACIDO ORGANICO), ii) AGITAR Y OPCIONALMENTE CALENTAR A LA TEMPERATURA DE EBULLICION DEL DISOLVENTE, iii) AGITAR PARA ENFRIAR, EL COCRISTAL PRECIPITA O PRECIPITA DESPUES DE RECOGERSE EN UN SEGUNDO DISOLVENTE, iv) EL PRECIPITADO OBTENIDO SE FILTRA Y SE SECA. DICHO COCRISTAL ES UTIL
