Co-crystals of agomelatine, a process for there preparation and pharmaceutical compositions containing them

A co-crystal of agomelatine, comprising:

• agomelatine, or N-[2-(7-methoxy-1-naphthyl)ethyl]acetamide of formula (I)
• and
• an organic acid which is in a solid state at ambient temperature, wherein the co-crystal is selected from:
• N-[2-(7-methoxy-1-naphthyl)ethyl]acetamide/para-hydroxybenzoic acid (2/1);
• N-[2-(7-methoxy-1-naphthyl)ethyl]acetamide/para-hydroxybenzoic acid (1/2);
• N-[2-(7-methoxy-1-napthyl)ethyl]acetamide/citric acid (1/1);
• N-[2-(7-methoxy-1-naphthyl)ethyl]acetamide/oxalic acid (2/1);
• N-[2-(7-methoxy-1-napthyl)ethyl]acetamide/gallic acid (2/1);
• N-[2-(7-methoxy-1-naphthyl)ethyl]acetamide/maleic acid (1/1);
• N-[2-(7-methoxy-1-naphthyl)ethyl]acetamide/malonic acid (1/1);
• N-[2-(7-methoxy-1-naphthyl)ethyl]acetamide/glutaric acid (1/1);
• N-[2-(7-methoxy-1-naphthyl)ethyl]acetamide/glycolic acid (1/1);
• and
• N-[2-(7-methoxy-1-naphthyl)ethyl]acetamide/ketoglutaric acid (1/1).