Biol. Pharm. Bull. 29(4) 705—708 (2006)

suffering from febrile convulsions. Previous studies of clinical applications of rectal DZP have shown that intermittent administration of DZP suppositories during the febrile period prevents recurrent febrile convulsions. In addition to DZP suppository, acetaminophen (AAP) suppositories are occasionally used to ease suffering by high fever. However, the simultaneous combination of DZP and AAP suppositories has been reported to reduce the plasma concentration of DZP in infants with recurrent febrile convulsions. It is speculated that when an AAP suppository prepared with an oleaginous base is administered simultaneously with a DZP suppository, portions of the once-dissolved lipid-soluble DZP are reincorporated into the oleaginous base of the AAP suppository, which has fused in the rectal cavity. However the reason for these drug-base interactions of DZP and AAP suppositories is not clear. Thus, in the present study, we investigated the effect of simultaneous administration of DZP suppository and oleaginous base on the pharmacokinetics and pharmacodynamic action of DZP.