Administration of 1,3-dimethoxymethyl-5,5-diphenylbarbituric acid and its related compounds with food increases the bioavailability of these compounds. The ratios (fasting/fed) for geometric mean AUC.sub.0-t were 35.6% (DMMDPB), 36.6% (MMMDPB) and 65.3% (DPB) and the geometric mean C.sub.max were 14.6% (DMMDPB), 31.9% (MMMDPB) and 62.9% (DPB). The cyclic ureides may be administered to a subject before or after ingestion of food within a defined time period.