Acute encephalopathy with hyperammonemia and dicarboxylic aciduria during calcium hopantenate therapy: a patient report

We report a 3-year-old Japanese girl who developed acute encephalopathy while receiving calcium hopantenate (Calcium D-(+)-4-(2, 4-dihydroxy-3,3-dimethylbutyramido) butyrate hemihydrate). She had hyperammonemia, elevated CPK, lactic acidemia and pyruvic acidemia, however, she did not show elevated SGOT or SGPT. Calcium hopantenate has been used in Japan for the treatment of mental retardation with behavior abnormalities. Recently there have been three reports on the occurrence of Reye-like syndrome in patients receiving this drug. Clinical signs and laboratory data of these patients are similar to those of Reye syndrome. Calcium hopantenate causes pantothenic acid deficiency in the young rat, which may reduce the content of coenzyme A. If this drug decreases coenzyme A biosynthesis, it may reduce beta-oxidation of fatty acids and levels of dicarboxylic acids would increase because of increasing omega-oxidation. We suspect that there is a possible relationship between the occurrence of acute encephalopathy and calcium hopantenate therapy.