Triamterene

Dyrenium (triamterene) is indicated in the treatment of edema associated with congestive heart failure, cirrhosis of the liver and the nephrotic syndrome; steroid-induced edema, idiopathic edema and edema due to secondary hyperaldosteronism. Dyrenium may be used alone or with other diuretics, either for its added diuretic effect or its potassium-sparing potential. It also promotes increased diuresis when patients prove resistant or only partially responsive to thiazides or other diuretics because of secondary hyperaldosteronism.

Usage in Pregnancy . The routine use of diuretics in an otherwise healthy woman is inappropriate and exposes mother and fetus to unnecessary hazard. Diuretics do not prevent development of toxemia of pregnancy, and there is no satisfactory evidence that they are useful in the treatment of developed toxemia. Edema during pregnancy may arise from pathological causes or from the physiologic and mechanical consequences of pregnancy.

Diuretics are indicated in pregnancy (however, see PRECAUTIONS below) when edema is due to pathologic causes, just as they are in the absence of pregnancy. Dependent edema in pregnancy, resulting from restriction of venous return by the expanded uterus, is properly treated through elevation of the lower extremities and use of support hose; use of diuretics to lower intravascular volume in this case is illogical and unnecessary. There is hypervolemia during normal pregnancy which is harmful to neither the fetus nor the mother (in the absence of cardiovascular disease), but which is associated with edema, including generalized edema, in the majority of pregnant women.

If this edema produces discomfort, increased recumbency will often provide relief. In rare instances, this edema may cause extreme discomfort which is not relieved by rest. In these cases, a short course of diuretics may provide relief and may be appropriate.

Adult Dosage Dosage should be titrated to the needs of the individual patient. When used alone, the usual starting dose is 100 mg twice daily after meals. When combined with another diuretic or antihypertensive agent, the total daily dosage of each agent should usually be lowered initially and then adjusted to the patient’s needs.

The total daily dosage should not exceed 300 mg. Please refer to PRECAUTIONS−General. When Dyrenium (triamterene) is added to other diuretic therapy or when patients are switched to Dyrenium from other diuretics, all potassium supplementation should be discontinued.

There have been isolated reports of hypersensitivity reactions; therefore, patients should be observed regularly for the possible occurrence of blood dyscrasias, liver damage or other idiosyncratic reactions. Periodic BUN and serum potassium determinations should be made to check kidney function, especially in patients with suspected or confirmed renal insufficiency. It is particularly important to make serum potassium determinations in elderly or diabetic patients receiving the drug; these patients should be observed carefully for possible serum potassium increases.

If hyperkalemia is present or suspected, an electrocardiogram should be obtained. If the ECG shows no widening of the QRS or arrhythmia in the presence of hyperkalemia, it is usually sufficient to discontinue Dyrenium (triamterene) and any potassium supplementation, and substitute a thiazide alone. Sodium polystyrene sulfonate may be administered to enhance the excretion of excess potassium.

The presence of a widened QRS complex or arrhythmia in association with hyperkalemia requires prompt additional therapy. For tachyarrhythmia, infuse 44 mEq of sodium bicarbonate or 10 mL of 10% calcium gluconate or calcium chloride over several minutes. For asystole, bradycardia or A-V block transvenous pacing is also recommended.

The effect of calcium and sodium bicarbonate is transient and repeated administration may be required. When indicated by the clinical situation, excess K+ may be removed by dialysis or oral or rectal administration of Sodium polystyrene sulfonate. Infusion of glucose and insulin has also been used to treat hyperkalemia.

Anuria. Severe or progressive kidney disease or dysfunction, with the possible exception of nephrosis. Severe hepatic disease. Hypersensitivity to the drug or any of its components. Dyrenium (triamterene) should not be used in patients with pre-existing elevated serum potassium, as is sometimes seen in patients with impaired renal function or azotemia, or in patients who develop hyperkalemia while on the drug.

Patients should not be placed on dietary potassium supplements, potassium salts or potassium-containing salt substitutes in conjunction with Dyrenium. Dyrenium should not be given to patients receiving other potassium-sparing agents, such as spironolactone, amiloride hydrochloride, or other formulations containing triamterene. Two deaths have been reported in patients receiving concomitant spironolactone and Dyrenium or Dyazide ® . Although dosage recommendations were exceeded in one case and in the other serum electrolytes were not properly monitored, these two drugs should not be given concomitantly.

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.

Pregnancy Teratogenic Effects: Reproduction studies have been performed in rats at doses as high as 20 times the Maximum Recommended Human Dose (MRHD) on the basis of body weight, and 6 times the MRHD on the basis of body-surface area, without evidence of harm to the fetus due to triamterene. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed. Nonteratogenic Effects: Triamterene has been shown to cross the placental barrier and appear in cord blood.

The use of triamterene in pregnant women requires that the anticipated benefits be weighed against possible hazards to the fetus. These possible hazards include adverse reactions which have occurred in the adult.

Nursing Mothers: Triamterene has not been studied in nursing mothers. Triamterene appears in animal milk and is likely present in human milk. If use of the drug product is deemed essential, the patient should stop nursing.

Adverse effects are listed in decreasing order of frequency; however, the most serious adverse effects are listed first, regardless of frequency. All adverse effects occur rarely (that is, 1 in 1000, or less). Hypersensitivity: anaphylaxis, rash, photosensitivity. Metabolic: hyperkalemia, hypokalemia.

Renal: azotemia, elevated BUN and creatinine, renal stones, acute interstitial nephritis (rare), acute renal failure (one case of irreversible renal failure has been reported). Gastrointestinal: jaundice and/or liver enzyme abnormalities, nausea and vomiting, diarrhea. Hematologic: thrombocytopenia, megaloblastic anemia.

Central Nervous System: weakness, fatigue, dizziness, headache, dry mouth. To report SUSPECTED ADVERSE REACTIONS, contact Advanz Pharma (US) Corp. at 1-877-370-1142 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.