Long-term treatment of juvenile Huntington's chorea with dipropylacetic acid

Since the proposed mode of action of dipropylacetic acid, an anticonvulsant, is to increase central nervous system gamma-aminobutyric acid levels, we used this agent to treat identical twins with juvenile Huntington's chorea. Their clinical status did not improve immediately after they received dipropylacetic acid. Furthermore, long-term administration (over a year) of high doses of the agent (up to 2,400 mg per day; 92 mg per kilogram per day) did not seem to alter the slow progression of their disease. Prior to treatment with dipropylacetic acid, the twins had normal cerebrospinal fluid gamma-aminobutyric acid levels. In addition, cerebrospinal fluid 5-hydroxyindoleacetic acid and homovanillic acid were determined before and after 18 hours of high-dose probenecid. The former showed a normal threefold to fourfold increase after probenecid administration, but homovanillic acid had a distinctly subnormal turnover after probenecid, with only a threefold rather than the normal tenfold increase.