Trimethoprim 100mg Tablets
SUMMARY OF PRODUCT CHARACTERISTICS
1 NAME OF THE MEDICINAL PRODUCT
Trimethoprim 100mg Tablets
2. Qualitative and Quantitative Composition
Each tablet contains Trimethoprim BP 100 mg
3. Pharmaceutical Form
Uncoated tablet
Flat white tablet, with bevelled edges and embossed with ‘TR100’ on one side.
4 CLINICAL PARTICULARS
4.1 Therapeutic indications
Treatment of susceptible infections caused by trimethoprim sensitive organisms
including urinary and respiratory tract infections.
Prophylaxis of recurrent urinary tract infections.
4.2 Posology and method of administration
Acute infections:
Treatment should continue for a period of between 3 days (eg, uncomplicated bacterial cystitis in women) to 2 weeks depending on the nature and severity of the infection. The first dose may be doubled.
Adults and children over 12 years: 200mg twice daily Children 6 - 12 years: 100mg twice daily
Children under 6 years: This dosage form is not suitable for use in children younger than 6 years.
Elderly: Dosage is dependent on renal function. See special dosage schedule below.
Advised dosage schedule where there is reduced kidney function:
|
Creatinine Clearance (ml/sec) |
Plasma creatinine (micromol/l) |
Dosage advised |
|
Over 0.45 |
Men <250 Women <175 |
Normal |
|
0.25 - 0.45 |
Men 250-600 Women 175-400 |
Normal for 3 days then half dose |
|
Under 0.25 |
Men >600 Women >400 |
Half the normal dose |
Trimethoprim is removed by dialysis. However, it should not be administered to dialysis patients unless plasma concentrations can be estimated regularly.
Long-term treatment and prevention therapy:
Adults and children over 12 years: 100mg at night Children 6-12 years: 50mg at night. Where a single daily dose is required, dosage at bedtime may maximise urinary concentrations. The approximate dosage in children is 2mg trimethoprim per kg body weight per day.
Elderly: Dose depends on renal function. Refer to special dosage schedule above.
Route of administration For oral administration.
4.3 Contraindications
Severe hepatic insufficiency. Severe renal insufficiency. , unless plasma levels can be monitored regularly.Megaloblastic anaemia and other blooddyscrasias. Trimethoprim should not be administered to premature infants or children under 4 months of age. Trimethoprim should not be administered to pregnant women.
Hypersensitivity to trimethoprim or any other constituents of the medication
4.4 Special warnings and precautions for use
Patients with marked impairment of renal function:
Trimethoprim may cause depression of haemopoiesis. Regular haematological tests should be undertaken in patients receiving long term treatment and those predisposed to folate deficiency, (eg the elderly), to check for possible pancytopaenia. If there is evidence of folic acid deficiency, calcium folinate should be administered and response checked by haematologic monitoring. It may be necessary to discontinue trimethoprim.. Particular care should be exercised in the haematological monitoring of children on long term therapy.
Close monitoring of serum electrolytes is advised in patients at risk for hyperkalaemia (see section 4.8).
Monitoring of blood glucose is advised if co-administered with repaglinide (see section 4.5).
Acute porphyria
4.5 Interaction with other medicinal products and other forms of interaction
Folate antagonists and anticonvulsants: Trimethoprim may induce folate deficiency in patients predisposed to folate deficiency such as those receiving concomitant folate antagonists or anticonvulsants.
Bone marrow depressants: Trimethoprim may increase the risk for bone marrow aplasia. Cytotoxic agents such as azathioprine, mercaptopurine and methotrexate increase the risk of haematologic toxicity when given with trimethoprim.
Special care is necessary in patients receiving pyrimethamine in addition to trimethoprim.
Phenytoin and Digoxin: Careful monitoring of patients treated with digoxin or phenytoin is advised as trimethoprim may increase plasma concentration of these agents by increasing their elimination half life.
Rifampicin may decrease trimethoprim concentrations.
Diuretics: In elderly patients taking diuretics, particularly thiazides, there is an increased incidence of thrombocytopaenia with purpura.
Hyperkalaemia may be exacerbated by concomitant administration of diuretics, particularly potassium sparing diuretics and/or thiazide diuretics and eplerenone.
Cyclosporin: Increased risk of nephrotoxicity.
Procainamide: Trimethoprim increases plasma concentrations of
procainamide.
Dapsone: Plasma concentrations of trimethoprim and dapsone may increase when taken together.
Repaglinide: Trimethoprim may enhance the hypoglycaemic effects of repaglinide.
Anticoagulants: Trimethoprim may potentate the anticoagulant effect ofwarfarin and other coumarins.
Antibacterials: Plasma concentration of trimethoprim is possibly reduced by rifampicin. Plasma concentration of both drugs may increase when trimethoprim is given with dapsone.
Antimalarials: Increased antifolate effect when trimethoprim is given with pyrimethamine.
4.6 Pregnancy and lactation
Trimethoprim is contraindicated in pregnant women, premature infants or infants during the first few weeks of life.
Trimethoprim is excreted in breast milk. Effects on the suckling child are likely if therapeutic doses are administered to breast-feeding mothers. Trimethoprim is contraindicated if the breast fed infant is less than 4 months of age.
4.7 Effects on ability to drive and use machines
None that are known.
4.8 Undesirable effects
The following list of undesirable effects have been reported by health care professionals. Sometimes it may be difficult to distinguish reactions caused by the condition being treated from adverse drug reactions, which means that not all the listed reactions were caused by drug administration.
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.
Unknown: Megaloblastic anaemia, methaemoglobinaemia
Fatalities have been reported (especially in the elderly, or those with impairment of renal or hepatic function in whom careful monitoring is advised- refer to Section 4.3 Contraindications), however the majority of haematological changes are mild and reversible when treatment is stopped.
Immune system disorders
Very rare: Hypersensitivity, anaphylaxis, angioedema, drug fever, allergic vasculitis resembling Henoch-Schoenlein purpura, periarteritis nodosa, systemic lupus erythematosus.
Metabolism and nutrition disorders
Very common: Hyperkalaemia
Very rare: Hypoglycaemia, hyponatraemia, anorexia
Close supervision is recommended when Trimoptin 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 Trimoptin alone.
Eye disorders Very rare: uveitis
Respiratory, thoracic and mediastinal disorders Very rare: Cough, shortness of breath, wheeze, epistaxis
Gastrointestinal disorders Common: Nausea, diarrhoea, vomiting.
Very rare: Constipation, glossitis, stomatitis, pseudomembranous colitis, pancreatitis.
Unknown: Sore mouth
Hepatobiliary disorders
Very rare: Elevation of serum transaminases, elevation of bilirubin levels, cholestatic jaundice, hepatic necrosis. Cholestatic jaundice and hepatic necrosis may be fatal.
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.
Lyell’s syndrome (toxic epidermal necrolysis) carries a high mortality. Unknown: Pruritis
Musculoskeletal and connective tissue disorders Very rare: Arthralgia, myalgia and uveitis
Renal and urinary disorders
Very rare: Impaired renal function (sometimes reported as renal failure), haematuria
4.9 Overdose
Treat symptomatically, gastric lavage and forced diuresis can be used. Depression of haematopoiesis by trimethoprim can be counteracted by intramuscular injections of calcium folinate.
5 PHARMACOLOGICAL PROPERTIES
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Systemic antibacterial.
ATC Code: J01EA01 Mode of action
Trimethoprim is a dihydrofolate reductase inhibitor, inhibiting the conversion of bacterial dihydrofolic acid to tetrahydrofolic acid, required for the synthesis of some amino acids.
. Its effects are considerably greater on the cells of micro-organisms than on the mammalian cells. Trimethoprim may be bactericidal or bacteriostatic depending on growth conditions.
In vitro trimethoprim has effects on most Gram-positive and Gram-negative aerobic organisms, including enterobacteria such as E Coli, Proteus, Klebsiella pneumoniae, Streptococcus faecalis, Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus.
It has no effect on Mycobacterium tuberculosis, Neisseria gonorrhoeae, Pseudomonas aeruginosa, Treponema pallidum, Brucella abortis or anaerobic bacteria.
Mechanism(s) of resistance
Resistance to trimethoprim may be due to several mechanisms. Clinical resistance is often due to plasmid mediated dihydrofolate reductases that are resistant to trimethoprim: such genes may become incorporated into the chromosome via transposons. Resistance may also be due to overproduction of dihydrofolate reductase, changes in cell permeability, or bacterial mutants which are intrinsically resistant to trimethoprim because they depend on exogenous thymidine and thymine for growth. Emergence of resistance to trimethoprim does not appear to be any higher in areas where it is used alone than in areas where trimethoprim is used in combination with sulphonamides. Nonetheless, trimethoprim resistance has been reported in many species, and very high frequencies of resistance have been seen in some developing countries, particularly among Enterobacteriaceae.
EUCAST clinical MIC breakpoints to separate susceptible (S) pathogens from
resistant (R) pathogens are:
|
EUCAST Species-related breakpoints (Susceptible^/Resistant>) Units: mg/L | ||
|
Enterobacteriacea e |
Staphylococcus |
Enterococcus |
|
^2/>4 |
^2/>4 |
* ^0.032/>1 |
*The activity of trimethoprim is uncertain against enterococci. Hence the wild type ' population is categorized as intermediate.
5.2 Pharmacokinetic properties
Trimethoprim is readily absorbed from the gastro-intestinal tract and peak concentrations in the circulation occur about 3 hours after a dose is taken. It is bound to plasma proteins. Tissue concentrations are reported to be higher than serum concentrations with particularly high concentrations occurring in the kidneys and lungs but concentrations in the cerebrospinal fluid are about one half of those in the blood. About 40 to 50% of a dose is excreted in the urine within 24 hours mainly as unchanged drug. Urinary concentrations are generally well above the MIC of common pathogens for more than 24 hours after the last dose
5.3. Preclinical Safety Data
Not relevant
6.1. List of excipients
Lactose monohydrate Povidone K30 Crospovidone
Sodium starch glycolate (Type A) Magnesium stearate Purified water
6.2. Incompatibilities
None reported
6.3. Shelf Life
36 months
6.4. Special Precautions for Storage
Store below 25oC in a dry place. Protect from light.
6.5. Nature and Contents of Container
Polypropylene securitainer of 15, 18, 20, 21, 28, 30, 100 and 500 tablets with appropriate bellows or polyurethane foam wads. Also available in a PVC blister with aluminium foil containing 28 tablets.
6.6. Instruction for Use/Handling No special instructions.
Administrative Data 7. Marketing Authorisation Holder
ATHLONE LABORATORIES LIMITED, BALLYMURRAY,
CO. ROSCOMMON,
IRELAND.
8.
Marketing Authorisation Number
PL 6453/0043
9 DATE OF FIRST AUTHORISATION/RENEWAL OF THE AUTHORISATION
22/09/2005
10 DATE OF REVISION OF THE TEXT
01/10/13