acetylsalicylic acid: clinical use

Prescribing considerations

• Confirm the indication and formulation: gastro-resistant tablets have delayed release and are inappropriate when a rapid analgesic or antiplatelet effect is required.
• Assess gastrointestinal and bleeding history, concurrent medicines, renal and hepatic function, hydration, asthma or NSAID hypersensitivity, gout and G6PD deficiency.
• Review peri-procedural bleeding implications, including minor surgery and dental extraction.
• Consider the substantial sodium content of the selected effervescent product in people requiring sodium restriction.

Contraindications and cautions

• Hypersensitivity to aspirin, salicylates or relevant excipients; the effervescent product also contraindicates previous NSAID-associated asthma, rhinitis or urticaria.
• Active or previous peptic ulceration, haemorrhagic diathesis or specified bleeding disorders.
• Severe renal, hepatic or cardiac failure for the effervescent product.
• Concomitant methotrexate where contraindicated by the effervescent product licence.
• Product-specific third-trimester pregnancy restrictions and breastfeeding contraindications.
• Use in people under 16 unless specifically indicated by a clinician.

Monitoring

• Clinical evidence of gastrointestinal, intracranial or other bleeding; consider blood count where occult or chronic loss is suspected.
• Renal and hepatic function in at-risk patients or when interacting medicines are used.
• Blood pressure in patients with hypertension.
• Bronchospasm, rash, mucosal lesions or other hypersensitivity features.
• Tinnitus, vomiting, confusion, acid–base disturbance and other signs of salicylate toxicity where exposure or clinical presentation raises concern.

Clinical pharmacology

Acetylsalicylic acid has analgesic, antipyretic and anti-inflammatory activity and irreversibly inhibits platelet activation. It is rapidly absorbed from the small intestine in the buffered effervescent formulation, whereas gastro-resistant coating delays release until intestinal fluid is reached.

Formulation and product differences

• The buffered effervescent formulation is dissolved in water and contains a clinically relevant sodium load.
• Gastro-resistant tablets delay intestinal release, are normally swallowed whole and are unsuitable for rapid pain relief.
• The selected gastro-resistant product contains propylene glycol and benzyl alcohol, which may be relevant in hypersensitivity and severe renal or hepatic impairment.