Triamterene

Triamterene (trade name Dyrenium) is a potassium-sparing diuretic used in combination with thiazide diuretics for the treatment of hypertension and edema. This medication is best avoided in patients with chronic kidney disease due to the possibility of hyperkalemia. People using this drug should use salt substitute very cautiously.^[1]

1 Mechanism of action 2 Side effects 3 Caution with certain disease states 4 Cost 5 Dosing 6 Use in Meniere's disease 7 References

[edit] Mechanism of action

Triamterene directly blocks the epithelial sodium channel (ENaC) on the lumen side of the kidney collecting tubule. Other diuretics cause a decrease in the sodium concentration of the forming urine due to the entry of sodium into the cell via the ENaC, and the concomitant exit of potassium from the principal cell into the forming urine. Blocking ENaC prevents this from happening. Amiloride works in the same way.

[edit] Side effects

Common side effects may include a depletion of sodium, folic acid and calcium, nausea, vomiting, diarrhea, headache, dizziness, fatigue, and dry mouth. Serious side effects may include heart palpitations, tingling/numbness, fever, chills, sore throat, rash, and back pain. Triamterene can also cause kidney stones through direct crystallization or by seeding calcium oxalate stones.

Patients should be informed that triamterene may impart a blue fluorescent color to the urine.

[edit] Caution with certain disease states

Diabetes: Use with caution in patients with prediabetes or diabetes mellitus as there may be a change in glucose control.

Hepatic impairment: Use with caution in patients with severe hepatic dysfunction; in cirrhosis, avoid electrolyte and acid/base imbalances that might lead to hepatic encephalopathy.

Kidney stones: Use with caution in patients with kidney stones.

[edit] Cost

While the patent for triamterene expired long ago, there is no generic form of triamterene available.

According to prices at drugstore.com during the month of July 2008, the prices of Dyrenium are as follows...

50 mg (30): $39.99 100 mg (30): $53.54

[edit] Dosing

Usual adult dosing is 50-100 mg/day 1-2 times a day. Maximum recommended dose is 300 mg/day.

In children (unlabeled use), the initial dose is 1-2 mg/kg/day in 2 divided doses with an ultimate maximum recommended dose of 3-4 mg/kg/day (if this exceeds 300 mg/day, 300 mg/day is the maximum recommended dose).

Avoid use if the creatinine clearance is less than 10 ml/minute.

[edit] Use in Meniere's disease

While there is a lack of RCT evaluating the use of triamterene in the treatment of Meniere's disease, the typical treatment is 37.5 mg of triamterene with 25 mg of hydrochlorothiazide 1-2 capsules daily. This recommendation was given a grade of C (see http://www.aafp.org/afpsort.xml for information about the SORT evidence rating system). These recommendations were arrived at by evidence stated in