Professional view

aspirin: prescribing and clinical use

Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.

aspirin: clinical details

Prescribing considerations

Confirm the indication and formulation: gastro-resistant antiplatelet products are unsuitable for rapid analgesia or urgent platelet inhibition.
Assess gastrointestinal bleeding or ulcer history, bleeding tendency, asthma or NSAID sensitivity, renal and hepatic function, heart failure, gout, dehydration and concurrent medicines.
Older people are more susceptible to gastrointestinal and renal adverse effects.
Discuss planned surgery or dental procedures; avoid uncoordinated interruption of secondary-prevention therapy.
Do not use in people under 16 except for a specialist-directed indication because of the association with Reye's syndrome.

Contraindications and cautions

Hypersensitivity to aspirin, salicylates, NSAIDs or formulation excipients.
Active or recurrent peptic ulceration, gastrointestinal haemorrhage, haemophilia or another significant bleeding disorder.
Severe renal or hepatic impairment; severe heart failure is contraindicated for selected analgesic products.
Certain methotrexate regimens.
Product- and exposure-specific restrictions in late pregnancy.
Disprin is unsuitable for people allergic to peanut or soya; selected tablet products contain lactose.

Monitoring

Review for unusual bleeding, bruising, anaemia and gastrointestinal symptoms.
Monitor renal function when renal perfusion may be compromised or interacting medicines are used.
Consider liver-function monitoring in mild or moderate hepatic impairment.
Use enhanced blood-count and renal monitoring with methotrexate.
Consider salicylate toxicity with tinnitus, hearing disturbance, vomiting, confusion, hyperventilation or acid-base disturbance.

Clinical pharmacology

Acetylsalicylic acid acetylates cyclo-oxygenase. Platelet COX inhibition and thromboxane A2 suppression are irreversible for the affected platelet. Reduced prostaglandin synthesis accounts for analgesic, antipyretic and anti-inflammatory activity. Aspirin is rapidly hydrolysed to salicylate, and its metabolites are cleared mainly by the kidneys.

Formulation and product differences

Standard low-dose tablets are immediate-release oral antiplatelet products.
Gastro-resistant tablets release beyond the stomach and must be swallowed whole; they are unsuitable for rapid symptom relief.
Disprin is a dispersible oral analgesic formulation that must be dissolved in water and contains soy protein.
Aspirin suppositories are rectal analgesic, antipyretic and anti-inflammatory products containing aspirin in a hard-fat base.