Trimethoprim oral
- Drugs List
- Therapeutic Indications
- Dosage
- Contraindications
- Precautions and Warnings
- Pregnancy and Lactation
- Side Effects
- Monograph
Presentation
Oral formulations of trimethoprim
Drugs List
Therapeutic Indications
Uses
Antibiotic sensitive infections
Prophylaxis of recurrent urinary tract infections
Respiratory tract infections - upper and lower
Urinary tract infection
Unlicensed Uses
Acne vulgaris
Mild-mod Pneumocystis jiroveci pneumonia in pts intolerant of cotrimoxazole
Acne resistant to other antibacterials (prolonged treatment with trimethoprim may depress haemopoiesis, it should be initiated by specialists).
Mild to moderate pneumocystis pneumonia where co-trimoxazole is not tolerated or is inappropriate, dapsone may be given with trimethoprim.
Dosage
Adults
Acute infections
200mg twice daily.
Treatment period ranges between 3 to 14 days, depending on nature and severity of infection. The first dose can be doubled.
Long term treatment and prophylactic therapy
100mg at night.
Antibacterial resistant acne (unlicensed)
300mg twice daily. Prolonged treatment with trimethoprim may depress haemopoiesis.
Mild to moderate pneumocystis pneumonia where co-trimoxazole is not tolerated or is inappropriate (unlicensed)
5mg/kg every 6 to 8 hours. Given with dapsone.
Children
Not all brands are recommended in all age groups.
Acute infections:
The following dosages are based on 8mg/kg bodyweight daily.
Children aged over 12 years: 200mg twice daily.
Children aged 6 to 12 years: 100mg twice daily.
Children aged 6 months to 6 years: 50mg twice daily.
Children aged 6 weeks to 6 months: 25mg twice daily.
The following alternative dosing schedule may be suitable:
The following dosages are based on 4mg/kg bodyweight daily.
Children aged 6 to 12 years: 100mg twice daily.
Children aged 6 months to 5 years: 50mg twice daily.
Children aged 6 weeks to 5 months: 25mg twice daily.
Children aged 4 to 5 weeks: 4mg/kg twice daily.
Long term treatment and prophylactic therapy:
The following dosages are based on 2mg/kg bodyweight daily.
Children 12 to 18 years: 100mg at night.
Children 6 to 12 years: 50mg at night.
Children 6 months to 6 years: 25mg at night.
Children 6 weeks to 5 months: 12.5mg at night.
Children 4 to 6 weeks (unlicensed): 2mg/kg at night.
Mild to moderate pneumocystis pneumonia where co-trimoxazole is not tolerated or is inappropriate (unlicensed):
Trimethoprim 5mg/kg every 6 to 8 hours may be given with dapsone.
Neonates
Use in children aged under 6 weeks is unlicensed.
Acute infections:
3mg/kg as a single dose, then 1mg/kg to 2mg/kg twice daily.
Long term treatment and prophylactic therapy:
2mg/kg once daily at night.
Patients with Renal Impairment
Use with caution in patients with renal impairment to avoid accumulation. Regular haematological examination is required with long term therapy.
Trimethoprim is removed by dialysis. Do not administer to dialysis patients unless plasma concentrations can be estimated regularly.
The Renal Drug Handbook suggests short term folic acid supplements may be used in CKD 4 to 5.
The manufacturers of the solid formulations suggest the following:
Creatinine clearance over 0.45ml/second
Dose as usual.
Creatinine clearance 0.25 to 0.45ml/second
Day one to three: Dose as usual.
Day four and onwards: Use half usual dose for age.
Creatinine clearance under 0.25ml/second
Half the usual dose.
The manufacturer of the liquid formulation suggests the following regimen in renal impairment for treatment of infection in adults. Similar reductions should be made in children:
Creatinine clearance over 25ml/minute
200mg twice daily.
From day four onwards, monitor serum trimethoprim.
Creatinine clearance 10 to 25ml/minute
Day one: 200mg twice daily.
Day two and onwards: 100mg twice daily.
From day four onwards, monitor serum trimethoprim.
Creatinine clearance under 10ml/minute
Day one: 200mg twice daily.
Day two and onwards: 50 to 100mg twice daily. Monitor serum trimethoprim.
Contraindications
Children under 4 months
Haematological disorder
Porphyria
Precautions and Warnings
Children under 6 weeks
Elderly
Predisposition to folate deficiency
Breastfeeding
Folate deficiency
Galactosaemia
Glucose-galactose malabsorption syndrome
Hereditary fructose intolerance
Hyperkalaemia
Lactose intolerance
Pregnancy
Renal dialysis
Renal impairment
Severe hepatic impairment
Folate supplementation may be necessary in some patients
Not all available products are licensed for all age groups
Presentations with sorbitol unsuitable in hereditary fructose intolerance
Some formulations contain lactose
Perform blood counts on prolonged use of this treatment
Advise patient to report unexplained fever, sore throat, bruising, bleeding
May affect results of some laboratory tests
Caution in patients with, or predisposed to, folate deficiency (e.g. elderly patients). Consider administration of a folate supplement. Although an effect on folic acid 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.
Consider monitoring serum electrolytes in patients at risk for hyperkalaemia. Elderly patients or those taking high doses may be more susceptible to hyperkalaemia and hyponatraemia.
Pregnancy and Lactation
Pregnancy
Use trimethoprim with caution in pregnancy.
The manufacturer does not recommend the use of trimethoprim during pregnancy.
In the guidance published within Clinical Knowledge Summaries (CKS), when indicated, trimethoprim is suggested as one of a number of second line drugs for the treatment of symptomatic urinary tract infection (UTI) or asymptomatic bacteriuria, when other alternatives are not suitable. There may be teratogenic risk in the first trimester. CKS note that trimethoprim should be avoided in women who are folate deficient, taking a folate antagonist or who have been treated with trimethoprim in the last year. Schaefer considers trimethoprim an appropriate second line agent. Briggs suggests folic acid supplementation, at least 0.4 mg/day, may reduce the risk of congenital defects.
Trimethoprim is a folate antagonist, which raises concerns that its use during pregnancy may limit the availability of folic acid to the developing foetus. Human and animal data suggest that there may be risks associated with the use of trimethoprim in pregnancy, some reports and studies suggesting that use in the first trimester may result in structural defects.
Lactation
Use trimethoprim with caution in breastfeeding.
The manufacturers suggests although trimethoprim is excreted in breast milk this is not a contraindication to its short term use.
Schaefer suggests breastfeeding can continue during trimethoprim therapy. Hale suggests as trimethoprim is a folate antagonist, its long term use should be avoided in breastfeeding mothers or the infant should be considered for supplementation with folic acid.
Side Effects
Agranulocytosis
Allergic reaction
Altered liver enzymes values
Anaphylactic reaction
Angioedema
Aseptic meningitis
Blood dyscrasias
Cholestatic jaundice
Decreased haemopoiesis
Erythema multiforme
Exfoliative dermatitis
Fever
Folate deficiency
Gastro-intestinal disturbances
Glossitis
Headache
Hyperkalaemia
Increase in blood urea nitrogen
Jaundice
Leucopenia
Megaloblastic anaemia
Methaemoglobinaemia
Myalgia
Nausea
Photosensitivity
Pruritus
Rash
Serum creatinine increased
Sore mouth
Stevens-Johnson syndrome
Thrombocytopenia
Toxic epidermal necrolysis
Urticaria
Uveitis
Vomiting
Overdosage
It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.
The following number will direct the caller to the relevant local centre (0844) 892 0111
Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).
Further Information
Last Full Review Date: November 2016
Reference Sources
Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 3rd edition (2015) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.
Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 10th edition (2015) ed. Briggs, G., Freeman, R. Wolters Kluwer Health, Philadelphia.
Medications and Mothers' Milk, Sixteenth Edition (2014) Hale, T and Rowe, H, Hale Publishing, Plano, Texas.
Summary of Product Characteristics: Trimethoprim 100 mg tablets. Kent Pharmaceuticals Ltd. Revised August 2013.
Summary of Product Characteristics: Trimethoprim 50 mg/5ml Suspension. Pinewood Healthcare. Revised April 2011.
Summary of Product Characteristics: Trimogal tablets. Ennogen Pharma Limited. Revised July 2019.
The Renal Drug Handbook. Fourth Edition (2014) ed. Ashley, C and Dunleavy, A, Radcliffe Publishing Ltd, London.
Clinical Knowledge Summaries - Urinary Tract Infection (lower) - women. Revised December 2019.
Available at: https://cks.nice.org.uk/urinary-tract-infection-lower-women
NICE - Evidence Services
Available at: www.nice.org.uk
Last accessed: 09 June 2017
US National Library of Medicine. Toxicology Data Network. Drugs and Lactation Database (LactMed).
Available at: https://www.ncbi.nlm.nih.gov/books/NBK501922/
Trimethoprim Last revised: 31 October 2018
Last accessed: 19 May 2020
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