The present invention provides imidazotriazinone compounds which are inhibitors of phosphodiesterase 9. The present invention further provides processes, pharmaceutical compositions, pharmaceutical preparations and pharmaceutical use of the compounds in the treatment of PDE9 associated diseases or disorders in mammals, including humans.本發明提供咪唑三酮化合物,其為磷酸二酯酶9之抑制劑。本發明進一步提供該等化合物用於治療哺乳動物(包括人類)中與PDE9有關之疾病或病症的方法、其醫藥組合物、醫藥製劑及醫藥用途。