antipyrine t1/2 was especially prolonged in patients with a history of more severe symptoms , but there was no correlation with the degree of elevation in urinary excretion of the porphyrin precursors delta-aminolevulinic acid ( ala ) and porphobilinogen ( pbg ) .
C2917401
porphyrin precursors
C0002563
delta-aminolevulinic acid