The effect of
triamterene on urinary excretion of
prostaglandin E was studied, and the results were compared with those obtained with
spironolactone. Urinary excretion of immunoreactive
prostaglandin E was measured radioimmunologically.
Triamterene was administered in a dose of 100 mg/day for 8 days to 7 patients with
essential hypertension. Following the administration of
triamterene, urinary
prostaglandin E tended to increase. However, the increment was not significant. The lack of significant increase in urinary
prostaglandin E excretion during the administration of
triamterene contrasted with our previous finding with
spironolactone, in which a significant increase in
prostaglandin E excretion was observed on the first day of
spironolactone administration. Urinary Na excretion and urinary Na/K ratio were significantly increased and urine volume also tended to increase following the administration of
triamterene. Plasma
renin activity and plasma
aldosterone concentration were increased in all cases. However, there was no significant correlation between these parameters and urinary
prostaglandin E. These results suggest that the effect of
triamterene on renal
prostaglandin E synthesis is different from that of
spironolactone and that the change in urinary
prostaglandin E after the administration of
triamterene is not the reflection of the change in the renin-angiotensin-aldosterone system.