AGENT FOR PREVENTION/TREATMENT OF DISEASE CAUSED BY ACYCLOVIR-RESISTANT HERPESVIRUS

[Problems] To provide an agent useful for the prevention or treatment of various diseases associated with the infection with acyclovir-resistant viruses of the family Herpesviridae, specifically various infectious caused by herpes viruses, such as varicella associated with varicella-zoster virus infection, herpes zoster associated with recurrent infection with latent varicella-zoster virus, and herpes labialis, herpes encephalitis and genital herpes associated with HSV-1 and HSV-2 infection, and the like. [Means for Solving Problems] An N-[2-[(4-substituted phenyl)amino]-2-oxoethyl]tetrahydro-2H-thiopyran-4-carboxamide derivative in which the phenyl group is substituted at position 4 by a specific 5- or 6-membered heteroaryl group. This derivative has an excellent anti-viral activity against acyclovir-resistant herpes viruses and, therefore, is effective for the treatment of the diseases as mentioned above.