Table 3.
AzCERT classification, and therapeutic classes of drugs involved in QT-interval prolonging drug-drug interactions in elderly patients
| Classification scheme | n (interacting drugs) | %a |
|---|---|---|
| AzCERT classification | ||
| Known risk of TdP (List 1) | 254 | 48.8 |
| Possible risk of TdP (List 2) | 181 | 34.8 |
| Conditional risk of TdP (List 3) | 62 | 12.0 |
| Not included in AzCERT QT drugs lists (List 4)b | 23 | 4.4 |
| Therapeutic categories | ||
| Antidepressant (N06A) | 144 | 27.7 |
| Proton pump inhibitor (A02BC) | 91 | 17.5 |
| Antipsychotic (N05A) | 85 | 16.3 |
| Antinausea (A04AA) | 46 | 8.8 |
| Antimicrobial (J01MA/J01FA) | 39 | 7.5 |
| H2-Receptor Antagonist (A02BA01/02/03) | 15 | 2.9 |
| Antihistamine (R06AD) | 12 | 2.3 |
| Anticonvulsant (N03AX11) | 10 | 1.9 |
| Antidementia (N06D) | 10 | 1.9 |
| Diuretics (C03) | 10 | 1.9 |
| Antineoplastic & immunomodulating agents (L01/L02/L03) | 8 | 1.5 |
| Antimalarial (P01B) | 6 | 1.2 |
| Antifungal (D01AC) | 5 | 1.0 |
| Calcium channel blocker (C08CA01) | 5 | 1.0 |
| Antituberculars (J04A) | 5 | 1.0 |
| Antidiabetics (A10A/A10B) | 5 | 1.0 |
| Beta blocking agents (C07A) | 4 | 0.8 |
| Antiarrhythmics (C01B/C01E) | 4 | 0.8 |
| Drugs for airway obstructive diseases (R03) | 3 | 0.6 |
| Antivirals (J05A) | 3 | 0.6 |
| Platelet aggregation inhibitors (B01AC) | 2 | 0.4 |
| Lipid modifying agents (C10A/C10B) | 2 | 0.4 |
| Antithyroid(H03B) | 1 | 0.2 |
| Antiparkinsonian Drugs(N04) | 1 | 0.2 |
| Drugs for BPH(G04C) | 1 | 0.2 |
| Agents acting on Renin Angiotensin system (C09) | 1 | 0.2 |
AzCERT=Arizona Center for Education and Research on Therapeutics (CredibleMeds); TdP=Torsades de Pointes; Total number of QT-interval prolonging drug-drug interactions i.e., 288; aPercentage calculated from number of all interacting drugs i.e., 520; b“Not included in AzCERT QT drugs lists (List 4)” = Total number of drugs to avoid in congenital long QT (List 4) = 18 (including 3 two-drug combinations); This list contains drugs exclusively from List 4; overlapping drugs from CredibleMeds Lists 1-3 have been excluded