Each tablet of Captolab contains Captopril BP 25mg.

The beneficial effect of captopril in the treatment of hypertension and heart failure appears to result primarily from the suppression of Renin-Angiotensin-Aldosterone system.

Renin is an enzyme produced in the kidneys and released into the blood circulation where it acts on a plasma globulin substrate to produce Angiotensin II.

Captopril is a specific competitive inhibitor of Angiotensin I-converting Enzyme (ACE, a peptidyldipeptide carboxy hydrolase), the enzyme responsible for conversion of Angiotensin I (a decapeptide), to Angiotensin II. Angiotensin II is a potent endogenous vasoconstrictor substance. It also stimulates aldosterone secretion from the adrenal cortex, thereby contributing to sodium and fluid retention.


  • Mild to moderate essential hypertension alone or with thiazide therapy.
  • Severe hypertension resistant to other treatment.
  • As an adjunct in congestive heart failure.
  • As a prophylactic following myocardial infarction in clinically stable patients with or symptomatic left ventricular dysfunction.
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  • Diabetic nephropathy in insulin-dependent diabetes where microalbuminuria is greater than 30mg/day.

Dosage and administration

Captolab tablets are administered orally as follows


  • Used alone: 12.5 mg daily initially.
  • Maintenance dose: 25mg twice daily with a maximum of 50mg twice daily or 3 times daily but rarely in severe hypertension.
  • In the elderly or in renal impairment or if used in addition with a diuretic , 6.25mg twice daily initially, first dose at bed time.

Heart failure (adjunct)

  • 6.25 to 12.5mg initially under close medical supervision.
  • Usual maintenance dose: 25mg two to 3 times daily.
  • Usual maximum dose: 150mg daily

Prophylaxis following myocardial infarction

  • Initially 6.25mg starting as early as 3 days after infarction, then increased over several weeks to 150mg daily (if tolerated) in divided doses.

Diabetic nephropathy

  • 75mg to 100mg in divided doses, if further blood pressure reduction is required, other antihypertensives may be used in conjunction with Captolab.
  • In severe renal impairment: initially 12.5mg Captolab is given twice daily if concomitant diuretic therapy is required then a loop diuretic rather than a thiazide should be chosen.


Pronounced hypotension may occur at the start of treatment with Captolab particularly in patients with heart failure and in sodium or volume depleted patients like those who have received previous diuretic therapy.

A severe fall in blood pressure with ischaemic heart disease or cardiovascular disease can result in myocardial infarction or stroke.

Deterioration in renal function, including increasing blood concentrations of urea and creatinine and reversible acute renal failure has been reported. This occurs in patients with existing renal or renovascular dysfunction or heart failure and may be aggravated by hypovolaemia. Proteinuria has also occurred and has progressed to nephritic syndrome in some patients.

Neutropenia and agranulocytosis are some of the blood disorders that have been reported in patients with renal failure and those with collagen vascular disorders such as systemic lupus erythematosus and scleroderma.


  • Hypersensitivity to ACE inhibitors or to any of the constituents of Captolab
  • Pregnancy and patients who may become pregnant
  • Known or suspected renovascular disease
  • Aortic stenosis or outflow track obstruction
  • Porphyria

Excessive hypotension may occur when Captolab is used concurrently with diuretics, other antihypertensive or other agents including alcohol which lower blood pressure.

An additive hyperkalaemic effect may be produced when Captolab is used with potassium sparing diuretics, potassium supplements including potassium containing salt substitutes or other drug that cause hyperkalaemia (e.g. ciclosporin or indomethacin).

The adverse effect of Captolab on the kidneys may be potentiated by other drugs such as NSAIDs that can affect renal function. Captolab may cause false positive results in laboratory tests for acetone in urine

Overdosage and treatment

Excessive hypotension is the primary concern in overdosage and is best rectified by volume expansion with an intravenous infusion of normal saline for restoration of blood pressure.


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