Paramethadione (brand name Paradione) is an anticonvulsant drug of the chemical class called oxazolidinediones developed by the Illinois-based pharmaceutical company Abbott Laboratories (known as AbbVie since January 1, 2013 [1]), and approved by the Food and Drug Administration in 1949 for the treatment of absence seizures, also called partial seizures.

[5] Paramethadione acts to reduce T-type calcium currents in thalamic neurons which has been proposed to underlie the 3-Hz spike-and-wave discharge seen on electroencephalogram (EEG) during absence seizures.

[6][7] Paramethadione is associated with various adverse effects including sedation, increased visual sensitivity to light, GI distress, edema, nephropathy, neutropenia, myasthenia gravis-like syndrome, fatal aplastic anemia, and severe birth defects known as fetal trimethadione syndrome (or paramethadione syndrome).

[8][9] Paramethadione (brand name Paradione) was originally approved by the U.S. Food and Drug Administration (FDA) in 1949, as a second-line treatment for petit mal and absence seizures.

While limited information is available from the time, a pre-market clinical study found that paramethadione, an analog of trimethadione, was not quite as effective at alleviating seizures as trimethadione, however, it did have a significantly lower side effect profile in 85 patients over the course of 2 years.