TRIMETHOPRIM

Posology Acute infections:

Adults and children over 12 years of age: 200 mg twice daily Children 6 years to 12 years: 100 mg twice daily Children under 6 years of age: This dosage form is not suitable for use in children younger than 6 years; a more suitable dosage form (such as a suspension) should be used in this age group.

Elderly:

Depending on kidney function, see special dosage schedule. g. uncomplicated bacterial cystitis in women) to 2 weeks depending on the nature and severity of the infection. The first dose can be doubled.

Long-term treatment and prophylactic therapy:

Adults and children over 12 years: 100 mg at night Children 6 years to 12 years of age: 50 mg at night. Where a single dose is required, dosage at bedtime may maximise urinary concentrations. The approximate dosage in children is 2mg trimethoprim per kg body weight per day.

This dosage form is not suitable for use in children younger than 12 years; a more suitable dosage form (such as a suspension) should be used in this age group.

Elderly:

Depending on kidney function, see special dosage schedule. Dosage advised where there is reduced kidney function: eGFR (ml/min) Dosage advised Over 30 Normal 15- 30 Normal for 3 days then half dose. Under 15 Half the normal dose. Monitoring of renal function and serum electrolytes should be considered particularly with longer term use, in patients with impaired renal function.

Trimethoprim should only be initiated and used in dialysis patients under close supervision from specialists in both infectious disease and renal medicine. Trimethoprim is removed by dialysis. Monitoring trimethoprim plasma concentration may be considered with long term therapy but the value of this in individual cases should first be discussed with specialists in infectious disease and renal medicine.

Method of administration:

Oral

The frequencies of adverse events are ranked according to the following: very common (≥ 1/10), common (≥ 1/100 to < 1/10), uncommon (≥ 1/1,000 to < 1/100), rare (≥ 1/10,000 to < 1/1,000), very rare (< 1/10,000), not known (cannot be estimated from the available data).

The most frequent adverse effects at usual doses are pruritus and skin rash (in about 3 to 7% of patients) and mild, gastrointestinal disturbances including nausea, vomiting and glossitis. These effects are generally mild and quickly reversible on withdrawal of the drug.

Infections and infestations Common:

Monilial overgrowth.

Blood and lymphatic system disorders Very Rare:

Leucopenia, neutropenia, thrombocytopenia, pancytopaenia, bone marrow depression, agranulocytosis, aplastic anaemia, haemolytic anaemia, eosinophilia, purpura, haemolysis.

Not known:

Isolated cases of megaloblastic anaemia during prolonged therapy with trimethoprim, with higher doses than those recommended, have been reported. These effects are reversible with discontinuation of therapy and administration of calcium folinate.

Not known:

Trimethoprim may affect haematopoiesis. 3)), however the majority of haematological changes are mild and reversible when treatment is stopped.

Immune system disorders Very Rare:

Hypersensitivity, anaphylaxis, anaphylactoid reaction, drug fever, allergic vasculitis resembling Henoch-Schoenlein purpura, periarteritis nodosa, systemic lupus erythematosus.

Metabolism and nutrition disorders Very Common:

Hyperkalaemia (particularly in the elderly and in HIV patients) Very Rare: Hypoglycaemia, hyponatraemia, anorexia. Close supervision is recommended when Trimethoprim Tablets is used in elderly patients or in patients taking high doses as these patients may be more susceptible to hyperkalaemia and hyponatraemia.

Psychiatric disorders Very Rare:

Depression, hallucinations, confusional states, agitation, anxiety, abnormal behavior, insomnia and nightmares.

Nervous system disorders Common:

Headache Very Rare: Dyskinesias, aseptic meningitis, tremor, ataxia, dizziness, lethargy, syncope, paraesthesiae, convulsions, peripheral neuritis, vertigo, tinnitus. Aseptic meningitis was rapidly reversible on withdrawal of the drug, but recurred in a number of cases on re-exposure to either co-trimoxazole or to Trimethoprim Tablets alone.

Eye disorders Very Rare:

Uveitis.

Respiratory, thoracic and mediastinal disorders Very Rare:

Cough, shortness of breath, wheeze, epistaxis.

Gastrointestinal disorders Rare:

Nausea, vomiting, gastrointestinal disturbances Very Rare: Constipation, glossitis, stomatitis, pseudomembranous colitis, pancreatitis Not known: Sore mouth Hepatobiliary disorders Very Rare: Disturbances in liver enzyme values, elevation of serum transaminases, elevation of bilirubin levels, cholestatic jaundice, hepatic necrosis Cholestatic jaundice and hepatic necrosis may be fatal.

Renal and Urinary disorders Not known:

Raised serum creatinine and blood urea nitrogen levels. It is not known however, whether this represents inhibition of creatinine tubular secretion or genuine renal dysfunction.

Skin and subcutaneous tissue disorders Common:

Skin rashes, urticaria Very Rare: Photosensitivity, exfoliative dermatitis, fixed drug eruption, erythema multiforme, erythema nodusum, Stevens-Johnson Syndrome, toxic epidermal necrolysis, bullous dermatitis, purpura, angioedema.

Not known:

Pruritus, drug reaction with eosinophilia and systemic symptoms (DRESS) Musculoskeletal system disorders Very Rare: Myalgia, arthralgia 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. uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store

In patients with marked impairment of renal function, care should be taken to avoid accumulation and resulting adverse haematological effects. Monitoring of renal function and serum electrolytes should be considered particularly with longer term use.

Trimethoprim should only be initiated and used in dialysis patients under close supervision from specialists in both infectious disease and renal medicine. g. the elderly). Administration of a folate supplement should be considered. Although an effect on folic acid metabolism is possible, interference with haematopoiesis rarely occurs at the recommended dose.

If any such change occurs, folinic acid should reverse the effect. Elderly people may be more susceptible and a lower dose may be advisable. Trimethoprim may cause depression of haemopoiesis. g. the elderly), to check for possible pancytopenia.

Although an effect on folate metabolism is possible, interference with haematopoiesis rarely occurs at the recommended dose. If any such change is seen, folinic acid should reverse the effect. Elderly people may be more susceptible and a lower dose may be advisable.

If there is evidence of folic acid deficiency, calcium folinate should be administered and response checked by haematological monitoring. It may be necessary to discontinue trimethoprim. Particular care should be exercised in the haematological monitoring of children on long term therapy.

The usual caution in prescribing any drug for women of child bearing age should be exercised with trimethoprim. 8). Patients should be advised of the signs and symptoms and monitored closely for skin reactions. If signs and symptoms suggestive of these reactions appear, trimethoprim should be withdrawn immediately and an alternative treatment considered (as appropriate).

If the patient has developed a serious reaction such as SJS, TEN or DRESS with the use of trimethoprim, the treatment must not be restarted in this patient at any time. Trimethoprim should be used under careful medical supervision in neonates.

Patients and their carers should be told how to recognise signs of blood disorders and advised to seek immediate medical attention if symptoms such as fever, sore throat, rash, mouth ulcers, purpura, bruising or bleeding develop. 8).

Elevations in serum potassium have been observed in some patients treated with trimethoprim. g. heparin). 5). 5). Caution should be used in patients with acute porphyria. Patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption should not take this medicine Sodium This medicine contains less than 1 mmol sodium (23 mg) per dose, that is to say essentially ‘sodium free’.

1, megaloblastic anaemia and blood dyscrasias and severe hepatic insufficiency. Trimethoprim should not be administered to pregnant women, premature infants or children under 4 months of age