AMILORETIC® TABLETS
AMILORETIC® H.S. TABLETS
SCHEDULING STATUS:
S3
PROPRIETARY NAME
(and dosage form):
AMILORETIC® TABLETS
AMILORETIC® H.S. TABLETS
COMPOSITION:
Each Amiloretic tablet contains:
| Amiloride hydrochloride | 5 mg |
| Hydrochlorothiazide | 50 mg |
Each Amiloretic H.S. tablet contains
| Amiloride hydrochloride | 2,5 mg |
| Hydrochlorothiazide | 25 mg |
PHARMACOLOGICAL CLASSIFICATION:
A 18.1 Diuretics.
PHARMACOLOGICAL ACTION:
Hydrochlorothiazide and amiloride are both oral diuretics which act by reducing reabsorption of electrolytes from the renal tubules thereby increasing the excretion of sodium and chloride ions and consequently of water. Hydrochlorothiazide also increases the excretion of potassium ions while amiloride has the opposite effect and has been found to diminish the kaluretic effects of other diuretics i.e. hydrochlorothiazide in this combination.
Hydrochlorothiazide slightly increases the bicarbonate excretion without appreciable alteration to the acid-base balance or the pH of the urine. It has an anti-hypertensive effect and enhances the action of other hypotensive agents.
INDICATIONS:
Oedema of cardiac decompensation or associated with hepatic cirrhosis and corticosteroid therapy.
Essential hypertension.
CONTRA-INDICATIONS:
Patients with a hypersensitivity towards either hydrochlorothiazide or amiloride. Severe renal and/or hepatic insufficiency.
Patients with hyperkalaemia.
Safety in pregnancy, lactation and childhood has not been established.
Chlorothiazide crosses the placenta which may cause neonatal jaundice, thrombocytopenia, and electrolyte imbalances. Chlorothiazide is excreted in the breast milk. Treatment with thiazide diuretics can inhibit lactation.
The safe use of hydrochlorothiazide is contentious in patients with porphyria.
DOSAGE AND DIRECTIONS FOR USE:
Amiloretic: One tablet daily.
Amiloretic H.S.: One to two tablets daily.
SIDE-EFFECTS AND SPECIAL PRECAUTIONS:
Amiloride hydrochloride:
The following side-effects may occur: nausea, vomiting, abdominal pain, diarrhoea or constipation, paraesthesia, thirst, dizziness, skin rash, pruritus, weakness, muscle cramps, and minor psychiatric or visual changes. Orthostatic hypotension and rises in blood-urea-nitrogen concentrations have been reported. Its potassium-sparing effect may lead to hyperkalaemia. Occasional abnormalities in liver-function tests have been reported.
Hydrochlorothiazide:
The following side-effects have been reported: anorexia, gastric irritation, nausea, vomiting, constipation, diarrhoea, headache, dizziness, postural hypotension, paraesthesia, impotence, and yellow vision. Hypersensitivity reactions include skin rashes, photosensitivity, pulmonary oedema, and pneumonitis. Cholestatic jaundice, pancreatitis, and blood dyscrasias including thrombocytopenia and, less frequently, granulocytopenia, leucopenia, and aplastic- and haemolytic anaemia have been reported.
SPECIAL PRECAUTIONS:
Amiloride:
Amiloride should not be given to patients with hyperkalaemia or progressive renal failure and should not be given with other potassium-sparing drugs or potassium supplements. Elderly patients, and patients with impaired renal function or diabetes mellitus, are at particular risk of developing hyperkalaemia. It should be given with care to patients likely to develop acidosis, to patients with diabetes mellitus, and to those with impaired hepatic or renal function. Amiloride should be discontinued at least 3 days before glucose-tolerance tests are given to patients with diabetes mellitus because of the risks if patients are hyperkalaemic. Serum electrolytes and blood-urea-nitrogen should be estimated periodically.
Hydrochlorothiazide:
Hydrochlorothiazide should be used with caution in patients with impaired hepatic function since they may increase the risk of hepatic encephalopathy. They should also be given with caution in renal impairment since they can further reduce renal function. They may precipitate attacks of gout in susceptible patients. All patients should be carefully observed for signs of fluid and electrolyte imbalance, especially in the presence of vomiting or during parenteral fluid therapy. Thiazide diuretics may exacerbate or activate systemic lupus erythematosus in susceptible patients.
Hydrochlorothiazide and other thiazide diuretics may enhance the neuromuscular blocking action of competitive muscle relaxants, such as tubocurarine. They may enhance the effect of antihypertensive agents, while postural hypotension associated with thiazide diuretic therapy may be enhanced by concomitant ingestion of alcohol, barbiturates or opioids. The potassium depleting effect of thiazide diuretics may be enhanced by corticosteroids, corticotrophin, or carbenoxolone.
Hydrochlorothiazide and other thiazide diuretics may cause a number of metabolic disturbances. They may provoke hyperglycaemia and glycosuria in diabetic and other susceptible patients. They may cause hyperuricaemia and precipitate attacks of gout in some patients. Administration of thiazide diuretics may be associated with electrolyte imbalances including hypochloraemic alkalosis, hyponatraemia, and hypokalaemia. Hypokalaemia intensifies the effect of digitalis on cardiac muscle and administration of digitalis or its glycosides may have to be temporarily suspended. Patients with severe coronary artery disease and cirrhosis of the liver are particularly at risk from hypokalaemia.
Hyponatraemia may occur in patients with severe congestive heart failure who are very oedematous, particularly with large doses in conjunction with restricted salt in the diet. The urinary excretion of calcium is reduced. Hypomagnesaemia has also occurred. There is some evidence to suggest that electrolyte imbalances during long-term treatment with thiazides may be associated with an increased incidence of cardiac arrhythmias. Adverse changes in plasma lipids have also been noted, but their clinical significance is unclear.
Signs of electrolyte imbalance include dry mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pain and cramps and gastro-intestinal disturbances.
Concomitant administration of thiazide diuretics and lithium is not generally recommended since the association may lead to toxic blood concentrations of lithium. Blood-glucose concentrations should be monitored in patients taking antidiabetic agents, since requirements may change. Thiazide diuretics may interfere with a number of diagnostic tests, including tests for parathyroid function; serum concentrations of protein-bound iodine may increase without signs of thyroid disturbance.
KNOWN SYMPTOMS OF OVERDOSAGE AND PARTICULARS OF ITS TREATMENT:
Dehydration, hypochloraemic alkalosis and hypokalaemia or hyperkalaemia.
See “Side-effects and Special Precautions”.
Treatment is symptomatic and supportive.
| Amiloretic: | A flat, pale peach coloured bisected tablet with bevelled edges engraved with a mortar and pestle on one side. (diameter 8 mm.) |
| Amiloretic H.S.: | A flat, pale peach coloured bisected tablet with bevelled edges engraved with a mortar and pestle on one side. (diameter 6,5 mm.) |
PRESENTATION:
Packs containing 30, 100, 500 and 1000 tablets.
STORAGE INSTRUCTIONS:
Store below 25°C.
Protect from light and moisture.
KEEP OUT OF REACH OF CHILDREN.
