Influence of clonidine on the porphyrin metabolism in female rats.

Effects of different doses of clonidine (CAS 4205-90-7) (15, 150, or 300 micrograms/kg body weight) over a period of 3, 14, or 64 days on the activities of delta-aminolevulinic acid synthase (ALA-S) and the P450 dependent isoenzymes aminopyrine-N-demethylase (ADM), 7-ethoxycoumarin-O-deethylase (7-ECO-D), and 7-ethoxyresorufin-O-deethylase (7-ERO-D) as well as on the hepatic porphyrin and P450 content were studied in female rats. Additionally, the urinary excretion of total porphyrins, and porphyrin precursors delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) and the plasma clonidine level were measured. No changes in the activity of ALA-S and in the hepatic and urinary porphyrin, ALA and PBG contents were observed. An increase in the activities of ADM in the short and median term application of clonidine and of 7-ERO-D in the long term application was detected. It is concluded from these findings that clonidine has no effect on the porphyrin biosynthesis, but has an influence on the activities of P450 dependent isoenzymes ADM or 7-ERO-D.