BMA Concise Guide to Medicine & Drugs

Triamterene

Brand name Dytac

Used in the following combined preparations Dyazide (co-triamterzide), Frusene, Kalspare, Triam-Co

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Drug group Potassium-sparing diuretic

Overdose danger rating Low

Dependence rating Low

Prescription needed Yes

Available as generic Yes (in combined products)

GENERAL INFORMATION

Triamterene belongs to a class of drugs known as potassium-sparing diuretics. In combination with thiazide or loop diuretics, it is given for the treatment of hypertension and oedema (fluid retention). It may be used, either on its own or, more commonly, with a thiazide diuretic such as hydrochlorothiazide (as co-triamterzide) to treat oedema as a complication of heart failure, nephrotic syndrome, or cirrhosis of the liver. Triamterene has a mild effect on urine flow, which is apparent in 1–2 hours. For this reason, you should avoid taking the drug after about 4 pm. As with other potassium-sparing diuretics, unusually high levels of potassium may build up in the blood if the kidneys are functioning abnormally. Therefore, triamterene is prescribed with caution to people with kidney failure.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets, capsules.

Frequency and timing of doses 1–2 x daily after meals or on alternate days.

Adult dosage range 50–250mg daily.

Onset of effect 1–2 hours.

Duration of action 9–12 hours.

Diet advice Consume only small amounts of foods that are high in potassium, such as bananas, tomatoes, dried fruit, and “low salt” salt substitutes.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. However, if it is late in the day, do not take the missed dose, or you may need to get up at night to pass urine. Take the next scheduled dose as usual.

Stopping the drug Do not stop the drug without consulting your doctor; symptoms may recur.

Exceeding the dose An occasional unintentional extra dose is unlikely to be a cause for concern. But if you notice any unusual symptoms, or if a large overdose has been taken, notify your doctor.

POSSIBLE ADVERSE EFFECTS

Triamterene has few adverse effects. The main problem is the possibility of potassium being retained by the body, causing muscle weakness and heart rhythm problems; if these occur, stop taking the drug and consult your doctor. Triamterene may also colour your urine blue, but this is not a cause for concern. Digestive disturbances, headache, a rash, dry mouth, and thirst are other rare effects of the drug. Consult your doctor if digestive problems or headache are severe or if any of the other symptoms occur. You should also stop taking the drug if you develop a dry mouth, thirst, or a rash.

INTERACTIONS

Lithium Triamterene may increase the blood levels of lithium, leading to an increased risk of lithium toxicity.

Non-steroidal anti-inflammatory drugs (NSAIDs) may increase the risk of raised blood levels of potassium.

ACE inhibitors and angiotensin II blockers These drugs increase the risk of raised blood levels of potassium with triamterene.

Ciclosporin and tacrolimus These drugs may increase blood levels of potassium with triamterene.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have long-term liver or kidney problems.

· You have had kidney stones.

· You have gout.

· You are taking other medicines.

Pregnancy Not usually prescribed. May cause a reduction in the blood supply to the developing fetus. Discuss with your doctor.

Breast-feeding The drug passes into breast milk and may affect the baby. It could also reduce your milk supply. Discuss with your doctor.

Infants and children Not recommended.

Over 60 Increased likelihood of adverse effects. Reduced dose may therefore be necessary.

Driving and hazardous work No special problems.

Alcohol No known problems.

PROLONGED USE

Serious problems are unlikely, but levels of salts such as sodium and potassium may occasionally become abnormal during prolonged use.

Monitoring Blood tests may be performed to check on kidney function and levels of body salts.