EFFECTS OF 5,5-DIMETHYL-2,4-OXAZOLIDINEDIONE (DMO) ON ACID-BASE AND ELECTROLYTE EQUILIBRIA

¹ Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina

5,5-Dimethyl-2,4-oxazolidinedione (DM0), the product of demethylation of trimethadione, when administered to rats in high dosage causes a decrease in plasma bicarbonate and chloride and a decrease in intracellular pH of skeletal muscle. When DMO is given intravenously to dogs, the acute effect is a fall in plasma bicarbonate. When dosage is continued by mouth on a chronic schedule, plasma bicarbonate returns to normal and plasma chloride decreases. In man, DMO causes a decrease in plasma bicarbonate equivalent to the concentration of the DMO anion. There is no effect on plasma chloride. It is suggested that the effectiveness of DMO in petit ma! epilepsy may be attributed to its property of being an unmetabolizable, slowly excreted acid that accumulates in large amounts to produce changes in extracellular and intracellular acid-base equilibria, which in some way influence the incidence of seizures.