All
 D03 Heterocyclic Compounds D006571 +
 D03.383 Heterocyclic Compounds, 1-Ring D006573 +
 D03.383.742 Pyrimidines D011743 +
 D03.383.742.698 Pyrimidinones D011744 +
 D03.383.742.698.122 Alloxan D000496 
 D03.383.742.698.253 Barbiturates D001463 +
 D03.383.742.698.421 Cytosine D003596 +
 D03.383.742.698.715 Sparsomycin D013033 
 D03.383.742.698.875 Uracil D014498 +
 D03.383.742.698.700 Ritanserin D016713 
 D03.383.742.698.685 Risperidone D018967