cotrimoxazole
Table of Contents
co-trimoxazole
see also:
- the use of cotrimoxazole in elderly patients carries an increased risk of severe adverse reactions.
- may not be tolerated well in patients with HIV / AIDS
- do not use in those with G6PD deficiency as risk of haemolytic anaemia
- as with all drugs containing sulfonamides, caution is advisable in patients with porphyria or thyroid dysfunction
- 'slow acetylators' may be more prone to idiosyncratic reactions to sulfonamides
- category C in pregnancy
- take especial care with prolonged use:
- consider folate supplements if prolonged high-dose use.
- possible interference with folate metabolism, regular blood counts are advisable in patients on long-term therapy, especially in those at risk (alcoholics, elderly, rheumatoid arthritis, and malabsorption syndromes)
- regular FBE, urine analysis and renal function tests should be performed during long-term therapy
- patients with renal impairment a reduced or less frequent dosage is recommended in order to avoid accumulation of trimethoprim in the blood.
- high doses of trimethoprim, as used in patients with Pneumocystis carinii pneumonia, induce a progressive but reversible increase of serum potassium concentration in a substantial number of patients.
introduction
- cotrimoxazole is a broad spectrum antibiotic consisting of two anti-folate antibiotics - trimethoprim and the sulphonamide, sulfamethoxazole
- marketed as Bactrim DS and Septrim DS
- it's use has declined substantially over the past 20 years on the belief that the sulphonamide component adds little for most infections whilst causing most of the adverse reactions.
- it was mainly used for sinusitis, bronchitis, otitis media and urinary tract infections (UTIs) / cystitis
- the role in urinary tract infections (UTIs) / cystitis has now been replaced by trimethoprim
- it has a role in the treatment of Pneumocystis carinii pneumonitis but may not be well tolerated in patients with HIV / AIDS
adverse effects
- hypersensitivity reactions including potentially fatal Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN), hepatic necrosis, agranulocytosis and aplastic anaemia may occur but are rare
- NB. cross-sensitivity with other sulphonamides
- superinfection
- liver impairment
- renal impairment, interstitial nephritis
- renal calculi due to sulphonamide crystalluria (rare)
- seizures in those with epilepsy
- aseptic meningitis
- hallucinations, depression
- arthralgia, myalgia
- pulmonary infiltrates
- thrombocytopenia - especially elderly on diuretics
- prolongs the half-life of phenytoin
- multiple other drug interactions - see full PI
dose
usual dose
- usually bd dosing for total of 5 day course or for two days after symptoms resolve
- adults and children > 12 years:
- Bactrim DS and Septrim DS 800mg/160mg per tablet, pack of 10 tablets, 1rpt on PBS
- usual dose: 1 tablet twice daily
- children usual dose of oral suspension (200mg/40mg per 5ml, 1rpt on PBS):
- < 2 yrs: 2.5 mL twice daily
- 2-5 yrs: 2.5-5 mL twice daily
- 6-12 yrs: 5-10 mL twice daily
- may adjust dose in extremes of bodyweight
Pneumocystis carinii pneumonitis
- trimethoprim 20 mg/kg and sulfamethoxazole 100 mg/kg/24 hrs in equally divided doses every 6 hrs for 14 days.
- Renal impairment:
- ClCr > 25 mL/min: admin standard dose every 12 hrs for less than or equal to 14 days then 1/2 standard dose every 12 hrs;
- ClCr 15-25 mL/min: admin standard dose every 12 hrs for 3 days then every 24 hrs with plasma level monitoring;
- ClCr < 15 mL/min: not recommended
cotrimoxazole.txt · Last modified: 2012/01/16 00:40 by 127.0.0.1