Symptoms of overdose include increased diuresis, natriuresis, hypovolaemia and decrease of blood pressure. After an overdose, activated charcoal should be administered as soon as possible to decrease absorption of the drug. Fluid and electrolyte balance must be monitored. Sodium chloride infusion can be used to sustain blood pressure. Otherwise, the treatment is symptomatic.
Moderate or severe renal impairment (Creatinine Clearance < 25 ml/min). Hepatic coma and severe hepatic insufficiency. Anuria. Hyperkalaemia. Sodium depletion and accompanying hypovolemia. Hypersensitivity to sulfonamides (because of cross-sensitivity between sulfonamides and furosemide).
Not applicable.
Of the adverse events caused by furosemide and triamterene, most are linked to the pharmacological effects of the compounds, and they are more common in patients with multiple illnesses or compromised physical condition.
Furosemide:
| Blood and lymphatic system disorders | Rare or very rare (<1/1000, including case reports) | Bone marrow depression, aplastic anaemia, agranulocytosis, thrombocytopenia and haemolytic anaemia |
| Frequency not known | Leucopenia | |
| Metabolism and nutrition disorders | Very common or common (>1/100) | Dehydration*, hyponatraemia*, hypochloremic metabolic alkalosis*, hypokalaemia*, hypocalcaemia*, hypomagnesemia* (incidences of the last three are reduced by triamterene) |
| Uncommon (>1/1,000, <1/100) | Impaired glucose tolerance (by hypokalaemia)*, hyperuricaemia, gout, reduction of serum HDL-cholesterol, elevation of serum LDL-cholesterol, elevation of serum triglycerides | |
| Frequency not known | Hypercalciuria | |
| Nervous system disorders | Uncommon (>1/1,000, <1/100) | Tiredness*, dizziness*, headache*, paresthesias*, restlessness* |
| Frequency not known | Dizziness, fainting and loss of consciousness (caused by symptomatic hypotension) | |
| Eye disorders | Uncommon (>1/1,000, <1/100) | Visual disturbance* |
| Ear and labyrinth disorders | Uncommon (>1/1,000, <1/100) | Deafness (sometimes irreversible) |
| Rare or very rare (<1/1000, including case reports) | Tinnitus, reversible or irreversible loss of hearing (after large doses or prolonged use of furosemide). | |
| Frequency not known | The use of furosemide may also lead to the development of sensorineural hearing loss. | |
| Cardiac disorders | Uncommon (>1/1,000, <1/100) | Cardiac arrhythmias* |
| Frequency not known | Closure of the patent arterial duct may be hindered after birth, especially if administered in premature infants in the first week of life. | |
| Vascular disorders | Very common or common (>1/100) | Decreased blood pressure* |
| Uncommon (>1/1,000, <1/100) | Hypotension*, hypovolaemia | |
| Rare or very rare (<1/1000, including case reports) | Vasculitis | |
| Gastrointestinal disorders | Uncommon (>1/1,000, <1/100) | Dry mouth*, thirst*, nausea*, bowel motility disturbances* |
| Rare or very rare (<1/1000, including case reports) | Pancreatitis | |
| Hepato-biliary disorders | Rare or very rare (<1/1000, including case reports) | Cholestasis |
| Skin and subcutaneous tissue disorders | Rare or very rare (<1/1000, including case reports) | Urticaria, purpura, erythema multiforme, exfoliative dermatitis, photosensitivity reactions |
| Frequency not known | Bullous pemphigoid, toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome (SJS), acute generalised exanthematous pustulosis (AGEP) | |
| Musculoskeletal, connective tissue and bone disorders | Uncommon (>1/1,000, <1/100) | Muscle cramps* |
| Renal and urinary disorders | Uncommon (>1/1,000, <1/100) | Reduced diuresis*, urinary incontinence, urinary obstruction (in patients with hyperplasia of the prostate) |
| Rare or very rare (<1/1000, including case reports) | Nephrocalcinosis (in pre-term infants treated with furosemide secondary to hyperparathyroidism), interstitial nephritisacute renal failure | |
| General disorders and administration site conditions | Uncommon (>1/1,000, <1/100) | Fatigue* |
| Rare or very rare (<1/1000, including case reports) | Fever |
*= an undesirable effect attributable to fluid or electrolyte imbalance induced by furosemide
Triamterene:
| Blood and lymphatic system disorders | Rare or very rare (<1/1000, including case reports) | Megaloblastic anaemia, pancytopenia |
| Metabolism and nutrition disorders | Very common or common (>1/100) | Hyperkalaemia (incidence is reduced by furosemide) |
| Uncommon (>1/1,000, <1/100) | Hyperuricaemia | |
| Nervous system disorders | Uncommon (>1/1,000, <1/100) | Headache |
| Vascular disorders | Uncommon (>1/1,000, <1/100) | Hypovolaemia |
| Gastrointestinal disorders | Very common or common (>1/100) | Nausea, vomiting, diarrhoea |
| Uncommon (>1/1,000, <1/100) | Dry mouth | |
| Skin and subcutaneous tissue disorders | Uncommon (>1/1,000, <1/100) | Rashes |
| Rare or very rare (<1/1000, including case reports) | Photosensitivity reactions, pseudoporphyria | |
| Renal and urinary disorders | Uncommon (>1/1,000, <1/100) | Elevation of s-creatinine, transient renal insufficiency |
| Rare or very rare (<1/1000, including case reports) | Interstitial nephritis, urinary stones | |
| General disorders and administration site conditions | Rare or very rare (<1/1000, including case reports) | Serum sickness, weakness |
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via Yellow Card Scheme at: www.mhra.gov.uk/yellowcard.
None stated.
For the treatment of oedematous conditions, where a prompt diuresis is required and where potassium conservation is important: congestive heart failure, pulmonary oedema, cardiac oedema, hepatic oedema and ascites.
A fixed ratio combination should only be used if titration with component drugs separately indicates that this product is appropriate.
Pharmacotherapeutic group: furosemide and potassium-sparing agents, ATC code: C03EB01.
Furosemide:
Its effects are evident within 1 hour after a dose by mouth and lasts for about 4 to 6 hours.
Furosemide is a potent diuretic with a rapid action. Its effects are evident within 1 hour after a dose by mouth and lasts for about 4 to 6 hours. It has been reported to exert inhibiting effects on electrolyte reabsorption in the proximal and distal renal tubules and in the ascending Loop of Henle.
Excretion of sodium, potassium and chloride ions is increased and water excretion enhanced.
Unlike thiazide diuretics where, owing to their flat dose-response curve, very little is gained by increasing the dose, furosemide has a steep dose-response curve, which gives it a wide therapeutic range.
Triamterene:
Triamterene is a mild diuretic which appears to mainly act on the distal renal tubules. It produces a diuresis in about 2 to 4 hours, reaching a maximum effect in about 6 hours. Triamterene adds to the natriuretic but diminishes the kaliuretic affects of other diuretics and is used as an adjunct to furosemide to conserve potassium, in the treatment of refractory oedema associated with hepatic cirrhosis, congestive heart failure and the nephrotic syndrome.
Furosemide:
Absorption of furosemide is variable and affected by many factors, such as concomitant ingestion of food (which slows down and may reduce the absorption) and the comorbidity of the patient (absorption is reduced in patients with uncompensated cardiac failure and oedematous conditions). The mean time to peak concentration of furosemide in plasma after administration of oral tablet is around 1.5 h. Bioavailability of oral formulations varies between 20 and 80 %. No direct correlation exists between the absorbed dose and diuresis. Some enterohepatic recirculation exists. First-pass metabolism takes place in the intestinal wall and only 10 % of metabolism occurs in the liver. Furosemide binds variably to plasma proteins, mainly albumin and the free fraction varies between 1 and 4 %. The volume of distribution is 0.1 to 0.2 l/kg. Furosemide is metabolised in the kidney by glucuronic acid conjugation and excreted in the urine and faeces as conjugates. A very small fraction is metabolised to saluamine. Most of the parent drug is excreted unchanged into the glomerular fluid and urine by an active transport mechanism in the proximal tubule. Furosemide clearance is 2 mL/min/kg in normal patients. Clearance is influenced by age (reduces in neonates, premature infants and geriatrics), underlying disease state (reduces with cardiac disease, uremia or renal impairment) and drug interactions. Elimination half-life of healthy subjects is ½ to 2 hours, which is considerably extended in renal failure. The half-life may be slightly longer in patients with hepatic dysfunction or heart failure. In the elderly, the elimination depends on the renal function, which is usually lowered.
Triamterene:
Absorption of triamterene is variable and the bioavailability varies between 30 and 80 %. First-pass metabolism is quite extensive, up to 40 %. Peak concentration in plasma is reached in 1.5 to 2.4 hours.
45 to 70 % of the compound is bound to plasma proteins. Estimates of the volume of distribution vary considerably, from 2 to 13 l/kg. Triamterene is metabolised in the liver to hydroxytriamterene and sulfate-conjugated to give a pharmacologically active metabolite. Elimination half-life of the parent compound and metabolite is the same, 2 to 4 hours. 50 to 70 % is excreted in the urine (1 to 10 % as unchanged triamterene). Hepatic failure and renal failure both slow the elimination of triamterene.
Variable amounts are also excreted in the bile. Animal studies have indicated that triamterene crosses the placental barrier and is excreted in the breast milk.
Electrolyte imbalance monitoring
Electrolyte balance and blood creatinine of the patients receiving furosemide and triamterene must be monitored.
Pulmonary oedema
Treatment should be stopped gradually to avoid deterioration of cardiac insufficiency. Diuretics must be administered carefully to avoid hypotension and circulatory collapse in patients with pulmonary oedema caused by acute myocardial infarction.
Hepatic failure
Daily weight loss should not exceed 1 kg to avoid relative intravascular dehydration; particular care is required in hepatic failure and ascites. Caution should also be exercised in the presence of liver disease as hepatic coma may be precipitated in susceptible cases.
When treating patients with hepatic failure and ascites, the electrolyte balance must be carefully monitored and care taken that the daily weight loss due to diuresis does not exceed 900-1000 g/day. Hypotension must be avoided in these patients (risk of precipitating hepatic encephalopathy).
Folic acid deficiency
Development of megaloblastic anaemia is possible in patients having folic acid deficiency (e.g. in hepatic cirrhosis). Triamterene may worsen this condition as it is a weak folic acid antagonist. In patients considered at risk, red cell folate levels should be measured and replacement given as appropriate.
Uric acid
Furosemide and, to a lesser extent, triamterene may predispose the patient to the development of hyperuricaemia and precipitate gout attacks.
Diabetes
Furosemide may worsen the glucose balance in diabetic patients.
Cholesterol Levels
Furosemide may alter HDL, LDL cholesterol and triglyceride values.
Urinary output
Acute diuresis may cause urinary retention in patients with urinary outflow obstruction (such as prostatic hyperplasia). Urinary output must be monitored in these patients.
Particularly careful monitoring is necessary when treating premature infants (possible development of nephrocalcinosis/nephrolithiasis; renal function must be monitored and renal ultrasonography performed).
In the RISPERDAL placebo-controlled trials in older people with dementia, a higher incidence of mortality was observed in patients treated with furosemide plus risperidone (7.3 %; mean age 89 years, range 75-97) when compared to patients treated with risperidone alone (3.1 %; mean age 84 years, range 70-96) or furosemide alone (4.1 %; mean age 80 years, range 67-90). The increase in mortality in patients treated with furosemide plus risperidone was observed in two of the four clinical trials.
Concomitant use of risperidone with other diuretics (mainly thiazide diuretics used in low dose) was not associated with similar findings.
No pathophysiological mechanism has been identified to explain this finding and no consistent pattern for cause of death observed. Nevertheless, caution should be exercised and the risks and benefits of this combination or co-treatment with other potent diuretics should be considered prior to the decision to use. There was no increased incidence of mortality among patients taking other diuretics as concomitant treatment with risperidone. Irrespective of treatment, dehydration was an overall risk factor for mortality and should therefore be carefully avoided in older people with dementia.
NSAIDs
Co-administration with nonsteriodal anti-inflammatory analgesics (NSAIDs) should be avoided wherever possible. Where this is not possible particularly careful monitoring is required to ensure that the diuretic effect is not attenuated.
Urine
Triamterene may cause blue discolouration of the urine.
Galactose intolerance
Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose galactose malabsorption should not take this medicine.
Particular Caution and/or Dose Reduction Required
Symptomatic hypotension leading to dizziness, fainting or loss of consciousness can occur in patients treated with furosemide, particularly in the elderly, patients on other medications which can cause hypotension and patients with other medical conditions that are risks for hypotension.
Occasionally Furesis compositum may cause hypotension, especially at the start of therapy. This may manifest itself as dizziness or faintness. If affected, avoid driving or the use of machinery.
Posology
The dosage depends on individual requirements.
Adults:
The usual adult dose is ½ to 2 tablets, taken in the morning. Maximum daily dose is 6 tablets (300 mg of triamterene).
Paediatric population:
Not recommended for use in children.
Older people:
In older people there is normally no requirement for dosage adjustments unless a clinically significant impairment of renal or hepatic function also exists. Triamterene may accumulate and dosage may need to be reduced. Creatinine and serum electrolytes should be monitored.
Patients with renal insufficiency
Treatment must be avoided in patients with moderate to severe renal insufficiency due to the risk of accumulation of triamterene and hyperkalaemia.
Patients with hepatic insufficiency:
Treatment must be initiated using a small dose with careful monitoring of the serum electrolyte concentrations. The natriuretic potency of furosemide may be weakened in patients with hepatic insufficiency but the kaliuretic potency usually remains. Elimination of triamterene is slowed down and its efficacy is increased in severe hepatic insufficiency.
Method of administration
The tablets should be taken with a sufficient quantity of liquid, usually in the morning. Concomitant intake of food can reduce the absorption of furosemide by 30%, so the tablets should not be taken with meals.
No special instructions.
