Table 1.
Naranjo’s score
| Questions | Yes | No | Don’t know | Score given | |
|---|---|---|---|---|---|
| 1. Are there previous conclusive reports on this reaction? | 1 | 0 | 0 | 1 | |
| 2. Did the adverse event appear after the suspected drug was administered? | 2 | −1 | 0 | 2 | |
| 3. Did the adverse event improve when the drug was discontinued or a specific antagonist was administered? | 1 | 0 | 0 | 1 | |
| 4. Did the adverse event reappear when the drug was readministered?* | 2 | −1 | 0 | 2 | |
| 5. Are there alternative causes (other than the drug) that could on their own have caused the reaction? | −1 | 2 | 0 | 2 | |
| 6. Did the reaction reappear when a placebo was given? | −1 | 1 | 0 | 0 | |
| 7. Was the drug detected in blood (or other fluids) in concentrations known to be toxic? | 1 | 0 | 0 | 0 | |
| 8. Was the reaction more severe when the dose was increased or less severe when the dose was decreased? | 1 | 0 | 0 | 1 | |
| 9. Did the patient have similar reaction to the same or similar drugs in previous exposure? | 1 | 0 | 0 | 0 | |
| 10. Was the adverse event confirmed by objective evidence? | 1 | 0 | 0 | 1 | |
| Total Score: 10 | |||||
| Total Score | Interpretation of scores | ||||
| ≥9 | Definite. The reaction followed a reasonable temporal sequence after drug exposure had been established in body fluids or tissues, followed a recognized response to the suspected drug, was confirmed by the improvement on withdrawing the drug and reappeared on re-exposure. | ||||
| 5–8 | Probable. The reaction followed a reasonable temporal sequence after a drug exposure, followed a recognized responsible to the suspected drug, was confirmed by withdrawal but not by exposure to the drug and could not be reasonably explained by the known characteristics of the patient’s clinical state. | ||||
| 1–4 | Possible. The reaction followed a temporal sequence after a drug exposure, possibly followed a recognized pattern to the suspected drug, and could be explained by characteristics of the patient’s clinical state. | ||||
| ≤0 | Doubtful. The reaction was likely related to factors other than a drug. |
*We accounted both drugs as one class since they share the same pharmacological mechanism. Hence, the positive answers to the questions 1, 2, 3, and 4.