Recommendations

It is important to realise that the use of aspirin is not in competition with other drugs. Thus any statement that it is more effective, or that it is less expensive than say, cholesterol lowering drugs, is inappropriate. aspirin should be considered in the treatment of any patient judged to be at high risk of a thrombotic event, and a low dose can be added to any other treatment or combination of treatments.

The form of aspirin which may be used in long-term prophylaxis appears to matter little. All formulations achieve adequate blood levels, except perhaps enteric-coated tablets in some patients. The aim is to expose platelets to adequate concentrations and the duration of the exposure appears not to matter. Therefore aspirin BP, soluble aspirin, mouth dispersible aspirin, buffered aspirin.... it appears not to matter which is used. It may be, however, that mouth dispersible tablets, which are pleasant to take without water, have advantages, and if these are foil-packed they can easily be carried in pocket or bag.

The one situation in which formulation may matter, is ‘Early’ and ‘Immediate’ Aspirin , as described earlier. Again let it be remembered that benefits from these are not proven, but would appear to be most reasonable expectations. The aim in both measures is to achieve adequate blood aspirin levels as rapidly as possible and so at least 300mg of a soluble formulation should be used.

Doses of 100 to 300mg aspirin per day have been well tested so there seems to be no reason to depart from the WHO recommendation: that is 100mg once a day. Again however, if ‘immediate’ aspirin is being recommended, it would seem sensible to give a larger dose, namely at least 300mg of soluble aspirin.

Recommendations
Patients who have had an MI, stroke or TIA*:
100 mg aspirin daily, indefinitely

Patients with unstable angina:
100 mg aspirin daily, indefinitely

Patients with stable angina:
these patients are at high risk of a thrombotic event, so:
100 mg aspirin daily, indefinitely

Patients with intermittent claudication:
these patients are also at high risk of a thrombotic event, so: 100 mg aspirin daily, indefinitely

Patients at high-risk of a cardiovascular event
‘high-risk’ is a clinical judgement. It would seem reasonable
to recommend low-dose aspirin in addition to whatever other drugs are judged appropriate.

In addition, patients judged to be at risk of a thrombotic event might be advised to carry a tablet of soluble aspirin with them
to be taken if sudden chest pain occurs.

Patients who have diabetes:
although these patients are at an increased risk of a cardiovascular event, there is probably no indication for aspirin prophylaxis, apart from the above indications, so treat as above.

Peter Elwood September 1997
*TIA = a transient ischamic attack, or a’mini-stroke’ the symptoms of which last less than 24 hours.