Trimethoprim

CLINICAL USE

Antibacterial agent

DOSE IN NORMAL RENAL FUNCTION

Treatment: 200 mg every 12 hours Prophylaxis: 100 mg at night

PHARMACOKINETICS

Molecular weight : 290.3

%Protein binding : 45

%Excreted unchanged in urine : 40–60

Volume of distribution (L/kg) : 1–2.2

half-life – normal/ESRD (hrs) : 8–10/20–49

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

>25 Dose as in normal renal function 15–25 Dose as in normal renal function <15 Dose as in normal renal function

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD : Not dialysed. Dose as in normal renal function

HD : Dialysed. Dose as in normal renal function

HDF/high flux : Dialysed. Dose as in normal renal function

CAV/VVHD : Probably dialysed. Dose as in normal renal function

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Anti-arrhythmics: increased risk of ventricular arrhythmias with amiodarone – avoid concomitant use; concentration of procainamide increased

Anti-epileptics: antifolate effect and concentration of phenytoin increased

Antimalarials: increased risk of antifolate effect with pyrimethamine

Ciclosporin: increased risk of nephrotoxicity Cytotoxics: increased risk of haematological toxicity with azathioprine and mercaptopurine; antifolate effect of methotrexate increased

ADMINISTRATION

Reconstition

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Route

Oral

Rate of Administration

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Comments

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OTHER INFORMATION

Serum creatinine may rise due to competition for renal secretion Hyperkalaemia is common in CKD 5 Short-term folic acid supplementation may be prescribed in patients with CKD 4-5 to cover antifolate effects of treatment dose .

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