PHARMACOLOGICAL CLASSIFICATION: A. 7.1 Vasodilators, Hypotensive Medicine
PHARMACOLOGICAL ACTION: The pharmacological action of Captopril is thought to be primarily due to the inhibition of the Renin-Angiotensin-Aldosterone system, but since it is also effective in managing hypertension where plasma renin activity is not elevated, other mechanisms are probably also involved.
Captopril inhibits the angiotensin-converting enzyme (ACE) and therefore prevents the conversion of the relatively inactive Angiotensin I to Angiotensin II which is one of the most potent endogenous vasoconstricting substances.
By the inhibition of ACE there is an increase in plasma renin activity and a decrease in aldosterone concentrations in the blood and urine. This may result in slightly raised serum-potassium concentrations and salt and water loss.
Captopril produces a decrease in total peripheral resistance and in patients with congestive heart failure, a reduction in both the preload and afterload.
The hypotensive effect of Captopril is enhanced by diuretics and other antihypertensive agents.
Captopril is rapidly absorbed after oral administration and produces maximum effect within one to two hours. Bioavailability is about 60% - 75%, however this is significantly reduced by food and thus should generally be given before meals.
About 30% is bound to plasma proteins.
The half-life of Captopril is two to three hours but this is increased in renal failure.
ADCO-CAPTOPRIL Tablets are indicated for use in the treatment of mild to moderate hypertension in adult patients. ADCO-CAPTOPRIL Tablets may be used alone or in combination with other anti-hypertensive agents especially thiazide diuretics. The hypotensive effects of Captopril and thiazides are additive. ADCO-CAPTOPRIL Tablets are also used as an adjunct to the treatment of congestive heart failure which has not responded adequately to or cannot be controlled by conventional therapy with diuretics and/or digitalis and in whom vasodilation is indicated.
CONTRA-INDICATIONS: Patients with known hypersensitivity to Captopril. Pregnancy: see WARNINGS.
Safety in lactation has not yet been established.
Safety and efficacy in children has not been established.
WARNINGS: Angioedema involving the extremities, face, eyes, lips, mucous membranes, tongue, glottis or larynx has been seen in patients treated with Captopril. Patients should be advised to immediately report to their doctor any symptoms suggesting angioedema (e.g. swelling of face, eyes, lips, tongue, larynx and extremities, difficulty in swallowing or breathing/hoarseness) and to discontinue therapy. If angioedema involves the tongue, glottis or larynx, airway obstruction may occur and be fatal. Emergency therapy including, but not necessarily limited to, subcutaneous administration of a 1:1 000 solution of adrenaline should be promptly instituted. Swelling confined to the face mucous membranes of the mouth, lips and extremities will usually resolve with discontinuation of Captopril, although some cases may require medical therapy. Use in patients with impaired renal function:
ADCO-CAPTOPRIL Tablets should be used with great caution in patients with impaired renal function, particularly if renovascular disease is present or suspected.
Some patients with renal disease, particularly those with bilateral renal artery stenosis, have developed increases in blood urea and serum creatinine after reduction of blood pressure with Captopril, usually along with a diuretic. Captopril dosage reduction or discontinuation of a diuretic, or both may be required. For some of these patients, it may not be possible to normalise blood pressure and maintain adequate renal perfusion. Some patients with heart failure have experienced a reduction in renal function during long term treatment.
For patients with prior renal disease of those receiving Captopril at high doses, urinary protein estimations should be done prior to treatment and monthly during the first months of therapy. If these show increasing amounts of urinary protein, a 24 hour quantitative determination of urinary protein should be done. If this exceeds one gram per day, the benefits and risks of continuing Captopril should be evaluated.
Neutropenia has occurred in some patients receiving Captopril, especially in those who had pre-existing impaired renal function, collagen vascular disease, immunosuppressant therapy or a combination of these complicating factors.
All patients receiving Captopril should be told to report any signs of infection (e.g. sore throat, fever).
A complete white blood cell count should be done immediately when infection is present. If the infection occurs during the first three months of therapy, Captopril should be discontinued until the results of the blood count are known.
Since Captopril decreases aldosterone production, elevation of serum potassium may occur especially in patients with renal failure. Potassium sparing diuretics or potassium supplements if needed, should be used with caution, since they may lead to a significant increase of serum potassium.
Patients treated for congestive heart failure, where the blood pressure was either normal or low, may experience decreases in mean blood pressure. This fall in blood pressure may occur after any of the first several dosages and may be associated with arrhythmia or conduction defects. Patients should be followed closely for the first two weeks of treatment and whenever the dose of ... (either) Captopril or diuretic, or both, is increased. ADCO-CAPTOPRIL Tablets should be used with caution in patients with collagen vascular disorders such as systemic lupus erythematous or scleroderma.
ACE inhibitors pass through the placenta and can be presumed to cause disturbances in foetal blood pressure regulatory mechanisms.
Oligohydrosis as well as hypotension, oliguria and anuria in newborns have been reported after administration of ACE inhibitors in the second and third trimester.
Cases of defective skull assification have been observed. Prematurity and low birth mass can occur.
Should a woman become pregnant while receiving an ACE-inhibitor, the treatment should be stopped promptly and switched to a different medicine. Should a woman contemplate pregnancy, the Doctor should consider alternative medication.
DOSAGE AND DIRECTIONS FOR USE:
ADCO-CAPTOPRIL Tablets should be taken one hour before meals.
Reduced dosages are indicated for patients with impaired renal function, the elderly and those receiving diuretics. ADCO-CAPTOPRIL Tablets may be used in combination with diuretics, as well as with other antihypertensive agents. Mild to Moderate Hypertension: The initial dose is 12,5 mg twice daily, increased gradually according to response.
The usual maintenance dose is 25 mg two to three times daily and should not exceed 50 mg three times daily. Congestive Heart Failure:
ADCO-CAPTOPRIL therapy should be initiated under close medical supervision.
The initial dose is 6,25 mg to 12,5 mg three times daily.
This dosage may be gradually increased to a maintenance dose of 25 mg three times daily and should not exceed 50 mg three times daily.
SIDE-EFFECTS AND SPECIAL PRECAUTIONS:
Skin: Skin rashes may be accompanied by pruritus, fever and eosinophilia. This effect usually occurs in the first four weeks of treatment and is usually self-limiting and may respond to antihistamines. Respiratory: A persistent dry cough has been reported. Gastro-intestinal: Taste disturbances may occur and this may be associated with a loss of weight. Stomatitis has been reported. Gastro-intestinal irritation and abdominal pain have also been reported. Hepatic: Hepatocellular injury and jaundice have been reported. Renal: Protein urea has occurred but mainly in patients with existing renal disease and this may develop into nephrotic syndrome.
Increasing blood concentrations of urea and creatinine as well as reversible acute renal failure have occurred in patients with existing renal dysfunction and this may be aggravated by hypovolaemia. ADCO-CAPTOPRIL Tablets may also be associated with increased plasma potassium concentrations. (See WARNINGS). Cardiovascular: Hypotension may occur at the initiation of ADCO-CAPTOPRIL Tablets therapy, particularly in patients with congestive heart failure or in patients with sodium or volume-depletion. This effect can be minimised by starting with a reduced dosage administered at night. A hypotensive episode following the initial dose of Captopril does not preclude further episodes. Tachycardia has been reported. Haematologic: Neutropenia and agranulocytosis have been reported in patients with renal failure. Thrombocytopenia and anaemia have also been reported (see WARNINGS).
Interactions: Indomethacin may reduce or cancel the hypotensive effect of ADCO-CAPTOPRIL Tablets. Salicylates appear to produce similar effects. ADCO-CAPTOPRIL Tablets may cause false positive results in tests for acetone in urine. There have been reports of increased serum digoxin concentrations with ADCO-CAPTOPRIL Tablets therapy. Lithium: Increased serum lithium levels and symptoms of lithium nephrotoxicity may occur with concomitant Captopril use. Co-administration should be handled with caution.
KNOWN SYMPTOMS OF OVERDOSAGE AND PARTICULARS OF ITS TREATMENT: Hypotension is the most likely effect of overdosage. This can be treated by volume expansion with an intravenous infusion of sodium chloride. Captopril is removed by haemodialysis. Treatment is symptomatic and supportive.
ADCO-CAPTOPRIL 25 mg Tablets: A white square shaped tablet, quadrisected on one side. ADCO-CAPTOPRIL 50 mg Tablets: A white oval shaped tablet with break bar.
ADCO-CAPTOPRIL 25 mg Tablets: Amber glass bottles and securitainers of 60 and 300 tablets or push-through blister packs of 20 tablets in containers of 60 tablets. ADCO-CAPTOPRIL 50 mg Tablets: Amber glass bottles and securitainers of 60 and 300 tablets or push-through blister packs of 20 tablets in containers of 60 tablets.
STORAGE INSTRUCTIONS: Store below 25°C in a well closed container. Protect from light. Keep out of reach of children.