1. The compound of formula (I)； wherein R is C 1-6 alkyl substituted with one, two, or 3 substituents selected from hydroxy, C 1-6 alkoxy, or C 1-6 cycloalkoxy； C 1-6 cycloalkyl substituted with one, two or three substituents selected from hydroxy, C 1-6 alkoxy or C 1-6 cycloalkoxy； or R is C 1-6 alkyl, hydroxy or C 1-6 alkoxy-C 1-6 alkyl； R 1 is hydrogen or C 1-6 alkyl； n is 1 or 2； R 1 is C 1-6 alkyl or C 1-4 fluoroalkyl； and its pharmaceutically acceptable salts； for use in a method of treating, preventing or slowing the development of cramping. 2. The compound of formula (I) according to claim 1, wherein R 1 is D 1: R 1 is C 1 -C 6 alkyl, hydroxy or C 1 -C 4 alkoxy-C 1-6 alkyl； R 1 is C 1-6 alkyl or C 1-4 fluoroalkyl； and pharmaceutically acceptable salts thereof； for use in a method of treating, preventing or slowing the development of cramping. 3. The compound of formula (I) according to claim 1, wherein R is D 2: R is hydrogen or C 1-6 alkyl； n is 1 or 2； R 1 is C 1-6 alkyl or C 1-4 fluoroalkyl； and pharmaceutically acceptable salts thereof； for use in a treatment method , preventing or slowing the development of cramping. 4. The compound of formula (I) according to claim 1, selected from the group consisting of: N- [6- (1-hydroxyethyl) -2,4-dioxo-7-trifluoromethyl-1,4-dihydro-2H-quinazolin-3- yl] methanesulfonamide； N- [6- (1-methoxyethyl) -2,4-dioxo-7-trifluoromethyl-1,4-dihydro-2H-quinazolin-3-yl] methanesulfonamide； N- [6- (1-hydroxypropyl ) -2,4-dioxo-7-trifluoromethyl-1,4-dihydro-2H-quinazolin-3-yl] methanesulfonamide； N- [6- (1-isopropoxyethyl) -2,4-dioxo-7-trifluoromethyl-1 , 4-dihydro-2H-quinazolin-3-yl] methanesulfonamide； N- [6- (1-ethoxyethyl) -2,4-dioxo-7-trifluoromethyl-1,4-dihydro-2H-quinazolin-3-yl] methanesulfone1. Соединение формулы (I)；гдеRпредставляет собой C-Cалкил, замещенный одним, двумя или тремя заместителями, выбранными из гидрокси, C-Cалкокси или C-Cциклоалкокси； C-Cциклоалкил, замещенный одним, двумя или тремя заместителями, выбран
