DYRENIUM- triamterene capsule
WellSpring Pharmaceutical Corporation
Warnings
Abnormal elevation of serum potassium levels (greater than or equal to 5.5 mEq/liter) can occur with all potassium-sparing agents, including Dyrenium. Hyperkalemia is more likely to occur in patients with renal impairment and diabetes (even without evidence of renal impairment), and in the elderly or severely ill. Since uncorrected hyperkalemia may be fatal, serum potassium levels must be monitored at frequent intervals especially in patients receiving Dyrenium, when dosages are changed or with any illness that may influence renal function.
DESCRIPTION
Each capsule for oral use, with opaque red cap and body, contains Triamterene USP, 50 or 100 mg, and is imprinted with the product name, DYRENIUM, strength (50 mg or 100 mg) and WPC 002 (for the 50-mg strength) and WPC 003 (for the 100-mg strength). Inactive ingredients consist of D&C Red No. 33, FD&C Yellow No. 6, Gelatin NF, Lactose NF, Magnesium Stearate NF, Sodium Lauryl Sulfate NF, Titanium Dioxide USP and Silicon Dioxide NF.
Triamterene is 2,4,7-triamino-6-phenyl-pteridine:
Triamterene Chemical Structure
(click image for full-size original)
Its molecular weight is 253.27. At 50�C, triamterene is slightly soluble in water. It is soluble in dilute ammonia, dilute aqueous sodium hydroxide and dimethylformamide. It is sparingly soluble in methanol.
CLINICAL PHARMACOLOGY
Triamterene has a unique mode of action; it inhibits the reabsorption of sodium ions in exchange for potassium and hydrogen ions at that segment of the distal tubule under the control of adrenal mineralocorticoids (especially aldosterone). This activity is not directly related to aldosterone secretion or antagonism; it is a result of a direct effect on the renal tubule.
The fraction of filtered sodium reaching this distal tubular exchange site is relatively small, and the amount which is exchanged depends on the level of mineralocorticoid activity. Thus, the degree of natriuresis and diuresis produced by inhibition of the exchange mechanism is necessarily limited. Increasing the amount of available sodium and the level of mineralocorticoid activity by the use of more proximally acting diuretics will increase the degree of diuresis and potassium conservation.
Triamterene occasionally causes increases in serum potassium which can result in hyperkalemia. It does not produce alkalosis, because it does not cause excessive excretion of titratable acid and ammonium.
Triamterene has been shown to cross the placental barrier and appear in the cord blood of animals.
