Table 4.
Prevalence of the QT-DDIs, TdP risk, therapeutic classes, severity and documentation of drugs involved in QT DDIs
| Classification scheme | Interacting drugs: n (%)a |
|---|---|
| TdP riskb | |
| Known risk of TdP (List 1) | 345 (59.9) |
| Possible risk of TdP (List 2) | 27 (4.7) |
| Conditional risk of TdP (List 3) | 39 (6.8) |
| Not included in AZCERT QT drug list (List 4) | 165 (28.6) |
| Therapeutic classes (ATC code) | |
| Antimicrobial (J) | 209 (36.3) |
| Antiemetic (A04) | 200 (34.7) |
| Antipsychotic (N05A) | 157 (27.3) |
| Muscle relaxant (M03) | 3 (0.5) |
| Kinase inhibitor (L01XE) | 3 (0.5) |
| Antidiarrheal (A) | 2 (0.4) |
| Anticancer (L01) | 2 (0.4) |
| Antidepressant (N06A) | 2 (0.4) |
| Classification on the basis of severityc | QT-DDIs: n (%)d |
| Major | 288 (100) |
| Classification on the basis of documentationc | QT-DDIs: n (%)d |
| Fair | 288 (100) |
AZCERT Arizona Center for Education and Research on Therapeutics, TdP torsades de pointes, QT DDIs QT prolonging drug-drug interactions, ATC Anatomical Therapeutic Chemical
aPercentage calculated in number of all interacting drugs i.e., 576
bTdP risk was based on the AZCERT QT drugs lists
cSeverity and documentation were based on Micromedex DrugReax classification
dPercentage calculated in total number of QT-DDIs i.e., 288