Aspirin

CLINICAL USE

NSAID:

Analgesic and antipyretic

Prophylaxis of cerebrovascular disease or myocardial infarction

DOSE IN NORMAL RENAL FUNCTION

Analgesia: 300 mg – 1 g every 4 hours. Maximum 8 g daily in acute conditions

Prophylaxis of cerebrovascular disease or myocardial infarction: 75–300 mg daily

PHARMACOKINETICS

Molecular weight :180.2

%Protein binding :80–90

%Excreted unchanged in urine : 2 (acidic urine); 30 (alkaline urine)

Volume of distribution (L/kg) :0.1–0.2

half-life – normal/ESRD (hrs) :2–3/Unchanged

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Dose as in normal renal function. See ‘Other Information’

10 to 20 : Dose as in normal renal function. See ‘Other Information’

<10 : Dose as in normal renal function. See ‘Other Information’

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :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 :Dialysed. Dose as in normal renal function

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

ACE inhibitors and angiotensin-II antagonists: antagonism of hypotensive effect, increased risk of nephrotoxicity and hyperkalaemia

Analgesics: avoid concomitant use of 2 or more NSAIDs, including aspirin – increased side effects; avoid with ketorolac – increased risk of side effects and haemorrhage

Antibacterials: possibly increased risk of convulsions with quinolonesAnticoagulants: effects of coumarins enhanced; possibly increased risk of bleeding with heparins and coumarins

Antidepressants: increased risk of bleeding with SSRIs and venlaflaxine

Antidiabetic agents: effects of sulphonylureas enhanced

Anti-epileptics: possibly increased phenytoin concentration

Antivirals: increased risk of haematological toxicity with zidovudine; concentration possibly increased by ritonavir

Ciclosporin: may potentiate nephrotoxicity

Cytotoxic agents: reduced excretion of methotrexate; increased risk of bleeding with erlotinibDiuretics: increased risk of nephrotoxicity; antagonism of diuretic effect, hyperkalaemia with potassium-sparing diuretics

Lithium: excretion decreased

Pentoxifylline: increased risk of bleeding

Tacrolimus: increased risk of nephrotoxicity

ADMINISTRATION

Reconstition

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Route

Oral

Rate of Administration

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Comments

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OTHER INFORMATION

Aspirin at analgesic/antipyretic dose is best avoided in patients with renal impairment, especially if severe

Antiplatelet effect may add to uraemic gastrointestinal and haematologic symptoms

Degree of protein binding reduced in ESRD

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