The invention relates to sodium and calcium salts of {8-fluoro-2-[4-(3-methoxyphenyl)piperazine-1-yl]-3-[2-methoxy-5-(trifluoromethyl)phenyl]-3,4-dihydroquinazoline-4-yl}acetic acid and solvates thereof, to the use thereof in a method of treatment and/or prophylaxis of virus infections and to the use thereof for producing drugs for use in methods of treatment and/or prophylaxis of diseases, more particularly the use thereof as antiviral agents, more particularly against cytomegaloviruses.