New research on treating horses with equine protozoal myeloencephalitis (EPM) has found dissolving toltrazuril sulfone, commercially known as ponazuril, in dimethylsulfoxide (DMSO) instead of water prior to oral administration in horses increases the bioavailability by three times and achieves therapeutic levels in both the blood and cerebrospinal fluid.

Ponazuril and related triazine-based antiprotozoal agents used to treat horses with EPM are highly lipid (fat) soluble. As a result, these agents dissolve poorly in the gastrointestinal system and are therefore poorly absorbed