Триамтерен

Описание

Triamterene is an inhibitor of the epithelial sodium channel (ENaC; IC₅₀ = 4.5 μM for the rat channel). In vivo, triamterene (0.5-32 mg/animal) enhances sodium secretion and decreases potassium secretion in adrenalectomized rats. Formulations containing triamterene have been used in the treatment of edema. This product is also available as an analytical reference standard .

Химические свойства

Yellow Solid

Использование

Triamterene is a potassium-sparing diuretic ie, it inhibits the urinary excretion of potassium

Биологические функции

Triamterene (Dyrenium) results in changes in urinary electrolyte patterns that are qualitatively similar to those produced by spironolactone. The mechanism by which this agents bring about the alterations in electrolyte loss, however, is quite different. Triamterene produces this effects whether or not aldosterone or any other mineralocorticoid is present. The action of this drug is clearly unrelated to endogenous mineralocorticoid activity, and this drug is effective in adrenalectomized patients.

Общее описание

Odorless yellow powder or crystalline solid. Melting point 316°C. Almost tasteless at first and with a slightly bitter aftertaste. Acidified solutions give a blue fluorescence. Used as a diuretic drug.

Реакции воздуха и воды

Sensitive to light; slowly oxidized upon exposure to air. Insoluble in water.

Профиль реактивности

2,4,7-Triamino-6-phenylpteridine neutralizes acids in exothermic reactions to form salts plus water. May be incompatible with isocyanates, halogenated organics, peroxides, phenols (acidic), epoxides, anhydrides, and acid halides. Flammable gaseous hydrogen may be generated in combination with strong reducing agents, such as hydrides.

Пожароопасность

Flash point data for 2,4,7-Triamino-6-phenylpteridine are not available; however, 2,4,7-Triamino-6-phenylpteridine is probably combustible.

Механизм действия

Triamterene is a pyrazine derivative that inhibits reabsorption of sodium ions without increasing excretion of potassium ions. It exhibits the same approximate effect as spironolactone; however, it does not competitively bind with aldosterone receptors. Its action does not have an effect on secretion of aldosterone or its antagonists, which are a result of direct action on renal tubules.
This potassium sparing diuretic causes a moderate increase in excretion of sodium and bicarbonate ions in urine, and it raises excretion of potassium and ammonia ions. It has little effect on urine volume.

Клиническое использование

Triamterene can be used in the treatment of congestive heart failure, cirrhosis, and the edema caused by secondary hyperaldosteronism. It is frequently used in combination with other diuretics except spironolactone. Amiloride, but not triamterene, possesses antihypertensive effects that can add to those of the thiazides. These K⁺-sparing diuretics have low efficacy when used alone, since only a small amount of total Na reabsorption occurs at more distal sites of the nephron.
These compounds are used primarily in combination with other diuretics, such as the thiazides and loop diuretics, to prevent or correct hypokalemia. The availability of fixed-dose mixtures of thiazides with nonsteroidal K⁺-sparing compounds has proved a rational form of drug therapy. Both triamterene and amiloride are available alone or in combination with hydrochlorothiazide.

Побочные эффекты

Because the actions of triamterene and amiloride are independent of plasma aldosterone levels, their prolonged administration is likely to result in hyperkalemia. Both amiloride and triamterene are contraindicated in patients with hyperkalemia.Triamterene should not be given to patients with impaired renal function. Potassium intake must be reduced, especially in outpatients.A folic acid deficiency has been reported to occur occasionally following the use of triamterene.