Physicochemical, Terminological, and Ethical Aspects of the Patenting of Substances and Medicinal Formulations of Abacavir Sulfate

Abstract

Using abacavir sulfate substance and medicinal formulations as an example, this being an agent used as an active pharmaceutical substance (APS) protected by a series of patents, we demonstrate that additional patenting has occurred because its physicochemical properties and the laws of chemistry have been ignored and professional terminology has been applied inappropriately. Eurasian patent No. EA 001809 includes substitution of the correct chemical name of the patented substances with an erroneous synonym, and the statement of claim, along with lack of novelty of the data on the properties of the patented substances, includes contradictory and unreliable information irrelevant to the item subject to the patent. This approach to prolonging the period of legal protection of a substance used as an APS is not acceptable either from the scientific or from the ethical points of view. Our x-ray diffraction study of abacavir sulfate (USP RS) showed that this substance and abacavir hemisulfate are identical, on the basis of published data on the structure of abacavir hemisulfate crystals. Each of these substances is a neutral salt and each has the atomic formula (C14H19N6O)2SO4 and a molecular weight of 670.76. Thus, repatenting a known APS (i.e., abacavir sulfate) as a new substance under a name incorrect for a neutral salt, i.e., (1S,4R)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]cyclopent-2-en-1-methanol hemisulfate, is unjustified.