Hydrochlorothiazide + Triamterene

Triamterene directly inhibits the exchange of Na for K and hydrogen in the distal renal tubule. Hydrochlorothiazide increases the excretion of Na and Cl ions, and consequently of water, by reducing electrolyte reabsorption from the renal tubules.

Hydrochlorothiazide is a thiazide diuretic. Thiazides affect the renal tubular mechanisms of electrolyte reabsorption, directly increasing excretion of sodium and chloride in approximately equivalent amounts. Indirectly, the diuretic action of Hydrochlorothiazide reduces plasma volume, with consequent increases in plasma renin activity, increases in aldosterone secretion, increases in urinary potassium loss, and decreases in serum potassium. The renin-aldosterone link is mediated by angiotensin II, so co-administration of anangiotensin converting enzyme (ACE) inhibitor tends to reverse the potassium loss associated with these diuretics.

Hypertension: Initially, 1 tablet (Hydrochlorothiazide 25 mg and Triamterene 50 mg) daily after the morning meal, adjust thereafter according to response. Max: 4 tab daily.

Oedema: Initially, 1 tablet (Hydrochlorothiazide 25 mg and Triamterene 50 mg) bid. Maintenance: 1 tab daily or 2 tab on alternate days. Max: 4 tab daily.

Take this medication by mouth as directed by your doctor, usually once daily in the morning with or without food. It is best to avoid taking this medication within 4 hours of your bedtime to prevent having to get up to urinate.

If you also take certain drugs to lower your cholesterol (bile acid-binding resins such as cholestyramine or colestipol), take this product at least 4 hours before or at least 4 to 6 hours after these medications.

The dosage is based on your medical condition and response to treatment. Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day. It is important to continue taking this medication even if you feel well. Most people with high blood pressure do not feel sick.

May reduce the renal clearance of lithium. May antagonise diuretic effect with NSAIDs, corticosteroids, oestrogens, combined OCs. Enhanced effect with other hypotensive agents, baclofen, tizanidine. May decrease arterial responsiveness to norepinephrine. Increases responsiveness to tubocurarine. Risk of acute renal failure with indometacin. Increased risk of hyperkalaemia with reboxetine, tacrolimus. Increased risk of ototoxicity and nephrotoxicity with platinum compounds (e.g. cisplatin).

Hyperkalaemia (≥5.5 mEq/L), hypercalcaemia, diabetic ketoacidosis, Addison’s disease, progressive renal failure, increasing hepatic dysfunction. Concomitant use with K supplements, other K-conserving drugs, including ACE inhibitors.

Nausea, vomiting, diarrhoea, dizziness, weakness, hypotension, headache, muscle cramps, dry mouth, thirst, anaphylaxis, rash, metabolic acidosis, pancreatitis. Rarely, SLE and photosensitivity.

Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Patients with prediabetes or DM, diabetic nephropathy, predisposition to gout, history of renal lithiasis. Hepatic or renal impairment. Pregnancy and lactation.

Combined antihypertensive preparations

Symptoms: Electrolyte imbalance, nausea, vomiting, weakness, polyuria, lassitude, fever, flushed face, hyperactive deep tendon reflexes, hypotension, cardiac arrhythmias.

Management: Induce immediate evacuation through emesis or gastric lavage. Pressor agents e.g. norepinephrine may be given in case of hypotension.

Store between 20-25°C. Protect from light.