It is shown that the drug teraphthal should be considered as a mixture of octasodium salt of cobalt(II) 2,3,9,10,16,17,23,24-octacarboxyphthalocianine (OCPC) and the product of its oxidation (component A) with OCPC octasodium salt and the products of profound destruction of a substance with similar elemental composition (component B). Quantitave estimation of the composition can be performed by two methods: (i) calculation of the results of elemental analysis (H, N, Co) and (ii) 1H NMR in combination with the measurement of weight loss on drying.