Triamterene trade name is Dyrenium.
It is a potassium-sparing diuretic often used in combination with thiazide diuretics for the treatment of high blood pressure or edema: Diazide Maxide
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.
Sodium channel blockers directly inhibit the entry of sodium into the sodium channels.
Pregnancy category AU: C
Bioavailability 30-70%
Protein binding 67%
Metabolism hydroxylation to para-hydroxytriamterene
Elimination half-life-1-2 hours, active metabolite 3 hours.
Excretion- renal <50%, 21% unchanged
Side effects:
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 cause kidney stones through direct crystallization or by seeding calcium oxalate stones.
Triamterene is best avoided in patients with chronic kidney disease due to the possibility of hyperkalemia.
It may impart a blue fluorescent color to the urine.
It may change glucose control in diabetes.
Used with caution in people with severe liver dysfunction.
Triamterene and indomethacin therapy may cause reversible acute kidney injury in some people.
Kidney stones: Used with caution in people with kidney stones.
Use should be avoided if the creatinine clearance is less than 10 ml/minute.
Ménière’s disease-typical treatment is 37.5 mg of triamterene with 25 mg of hydrochlorothiazide 1–2 capsules daily.