Table 2. Example of preventable and non-preventable adverse drug reactions.

Preventability Criteria	Example
	Preventable ADR	Non-Preventable ADR
Reaction occurred in a patient who previously had a documented prior allergic/reaction to the current causative drug.	Rash developed after administration of flucloxacillin in a patient with a documented allergy to penicillins [23, 43].	Rash developed after administration of flucloxacillin in a patient with no documented allergy to penicillins.
Reaction occurred due to any errors in medication process, including error during prescribing, dispensing, and administration.	Myopathy developed in a statin user who was recently prescribed systemic azole antifungal (Fail to identify drug-drug interaction) [23, 65].	Reaction developed without indication of possible drug-drug interaction.
	Exacerbations of asthma related with NSAID use (Contraindication overlooked) [67].	Reaction occurred despite appropriate selection of medication for patients’ condition.
	Rectal haemorrhage in a dabigatran user >75 years old related with incorrect dosage. Patient was given maximum recommended dosage (220mg/day), while in the SmPC of dabigatran, patient ≥ 75 years should receive lower dose (150 mg/day) [68]	Reaction occurred despite appropriate selection of dosage for patients’ condition.
	Hypoglycemic event due to medication administration error [69].	Reaction occurred despite appropriate dosing administration.
Required therapeutic drug monitoring or other necessary laboratory tests were not (adequately) performed.	Bleeding occurred in warfarin user with inadequate frequency of INR monitoring (led to elevated INR, e.g., INR > 4.5) [66].	Bleeding occurred despite the target INR had been achieved.
	Symptomatic hyperkalaemia in spironolactone user related with inadequate potassium monitoring [70]	Reaction occurred despite adequate laboratory monitoring and regimen adjustment.

NSAID: non-steroidal antiinflammatory drugs. SmPC: summary of product characteristic.