One of the major problems of the current therapy of brain diseases such as Alzheimer’s disease is the distribution of drugs to the central nervous system (CNS). Difficulties in traversing the blood–brain barrier (BBB) often impair the efficacy of valuable drugs. Using the ascorbic acid–drug conjugate concept, we have succeeded in developing a thiazolamide conjugate that shows an improved pharmacokinetic profile compared to the parent thiazolamide previously reported.