Table 1.
Reported patient's isolated chronic, nocturnal dry cough while on PO phenytoin (100 mg/day) as assessed by the Naranjo Adverse Drug Reaction Probability Scale.
| Question | Yes | No | Unknown | Patient's score |
|---|---|---|---|---|
| Are there any previous conclusive reports of this reaction? | + 1 | 0 | 0 | + 1 |
| Did the adverse event appear after the suspected drug was given? | + 2 | − 1 | 0 | + 2 |
| Did the adverse reaction improve when the drug was discontinued or a specific antagonist was given? | + 1 | 0 | 0 | + 1 |
| Did the adverse reaction appear when the drug was readministered? | + 2 | − 1 | 0 | 0 |
| Are there alternative causes that could have caused the reaction? | − 1 | + 2 | 0 | + 2 |
| Did the reaction reappear when a placebo was given? | − 1 | + 1 | 0 | 0 |
| Was the drug detected in any body fluid in toxic concentrations? | + 1 | 0 | 0 | 0 |
| Was the reaction more severe when the dose was increased or less severe when the dose was decreased? | + 1 | 0 | 0 | 0 |
| Did the patient have a similar reaction to the same or similar drugs in any previous exposure? | + 1 | 0 | 0 | 0 |
| Was the adverse event confirmed by any objective evidence? | + 1 | 0 | 0 | 0 |
| Patient's total score | + 6 |
Scoring algorithm: > 9 = definite ADR, 5–8 = probable ADR, 1–4 = possible ADR, 0 = doubtful ADR. ADR, adverse drug reaction.
Modified from Naranjo CA, Busto U, Sellers EM, et al. A method for estimating the probability of adverse drug reactions. Clin Pharmacol Ther. 1981 Aug; 30(2):239–245.