Drug Groups

approved

Description

A pteridine that is used as a mild diuretic. [PubChem]

Indication

For the treatment of edema associated with congestive heart failure, cirrhosis of the liver, and the nephrotic syndrome; also in steroid-induced edema, idiopathic edema, and edema due to secondary hyperaldosteronism.

Pharmacology

Triamterene, a relatively weak, potassium-sparing diuretic and antihypertensive, is used in the management of hypokalemia. Triamterene is similar in action to amiloride but, unlike amiloride, increases the urinary excretion of magnesium.

Toxicity

In the event of overdosage it can be theorized that electrolyte imbalance would be the major concern, with particular attention to possible hyperkalemia. Other symptoms that might be seen would be nausea and vomiting, other G.I. disturbances, and weakness. It is conceivable that some hypotension could occur. The oral LD₅₀ in mice is 380 mg/kg.

Affected Organisms

Biotransformation

Triamterene is primarily metabolized to the sulfate conjugate of hydroxytriamterene. Both the plasma and urine levels of this metabolite greatly exceed triamterene levels.

Absorption

Rapidly absorbed, with somewhat less than 50% of the oral dose reaching the urine.

Half Life

255 minutes (188 minutes for OH-TA-ester metabolite) after IV administration.

Protein Binding

55-67% (93% for the OH-TA-ester metabolite)

Clearance

* 4.5 l/min [total plasma clearance]
* 0.22 l/kg [renal plasma clearance]

References

External Links