The present invention relates to the field of anti-viral active agents, particularly the free base hemihydrate form of N-[5-(aminosulfonyl)-4-methyl-1,3-thiazol-2-yl]- N-methyl-2-[4-(2-pyridinyl)-phenyl]-acetamide as well as methods for the manufacture thereof. The present invention relates also to the use of the above compound in the treatment of human herpes virus infections and in the preparation of pharmaceuticals comprising said compound.本發明係關於抗病毒活性劑之領域,特定而言,N-[5-(胺基磺醯基)-4-甲基-1,3-噻唑-2-基]-N-甲基-2-[4-(2-吡啶基)-苯基]-乙醯胺之游離鹼半水合物形式以及用於製造其之方法。本發明亦係關於上述化合物在治療人類疱疹病毒感染中及在製備包含該化合物之藥品中之用途。