Trontell listed several clinical findings suggestive that a patient may be having an adverse drug reaction. The author is from the Food and Drug Administration (FDA).
Challenges:
(1) dechallenge - disappearance of the reaction after discontinuation of the drug
(2) rechallenge - recurrence of the reaction on re-exposure to the drug
Knowledge of pharmacology:
(1) adverse reaction understandable based on mechanism of drug action or drug pharmacology
(2) adverse reaction similar to adverse reactions seen with other drugs of the same class (also would include adverse reactions previously described for the agent)
(3) adverse reaction can be demonstrated in vitro or in animal studies
(4) adverse reaction follows the typical onset pattern for the type of injury
Exclusions:
(1) event otherwise unexplained based on patient and concurrent diseases (no other explanation)
(2) absence of prodromal signs and symptoms before drug exposure (no sign or symptom prior to drug exposure)
The presence of one or more of these findings should prompt a further evaluation of the patient-drug interaction.
Limitations:
• Some immune-mediated drug reactions may involve a previous exposure and may take some time to disappear.
• It may be difficult to recognize an adverse drug reaction in a patient who is unstable and receiving multiple drugs.
• Some adverse events may be delayed for years, as with chemotherapeutic agents.
• Re-exposure to a drug for rechallenge is often avoided.
