Table 3. Top 10 drug class-class interactions that were overridden.
| Object Drug / Class * | Precipitant Drug / Class † | Total no. (%) of alert overrides | |
|---|---|---|---|
| 1. | Calcium channel blockers (i.e., amlodipine; diltiazem; verapamil) | Statins (i.e., simvastatin; lovastatin) | 72 (14.5) |
| 2. | Phosphodiesterase type-5 inhibitors (i.e., sildenafil; tadalafil; vardenafil) | Alpha-adrenoceptor blocking drugs (i.e., tamsulosin; terazosin; doxazosin; alfuzosin) | 53 (10.7) |
| 3. | Antidepressants - selective serotonin reuptake inhibitors (i.e., citalopram; sertraline; fluoxetine; paroxetine; escitalopram; fluvoxamine) | 5 HT1 receptor agonists - ‘Triptans’ (i.e., sumatriptan; eletriptan; zolmitriptan; rizatriptan; almotriptan) | 36 (7.3) |
| 4. | Antidepressants - selective serotonin reuptake inhibitors (i.e., citalopram; sertraline) | Opioid Analgesics (i.e., tramadol) | 17 (3.4) |
| 5. | Antidepressants – tricyclic (i.e., amitriptyline; nortriptyline, doxepin, imipramine) | Opioid Analgesics (i.e., tramadol) | 16 (3.2) |
| 6. | Antibacterial drugs – macrolides (i.e., azithromycin; clarithromycin) | Statins (i.e., simvastatin; atorvastatin) | 16 (3.2) |
| 7. | Central nervous system stimulants (i.e., amphetamine / dextroamphetamine) | Proton pump inhibitors (i.e., omeprazole; pantoprazole) | 15 (3.0) |
| 8. | Antibacterial drugs – sulphonamides and trimethoprim (i.e., trimethoprim/sulfamethoxazole) | Oral anticoagulants – coumarins (i.e., warfarin) | 14 (2.8) |
| 9. | Lipid-regulating drugs – fibrates (i.e., gemfibrozil) | Statins (i.e., simvastatin; rosuvastatin) | 13 (2.6) |
| 10. | Sympathomimetics (e.g., epinephrine autoinjector) | Beta-adrenoceptor blocking drugs (i.e., propranolol; labetalol) | 13 (2.6) |
| Total | 265 (53.4) | ||
* The object drug was defined as the drug that has its therapeutic effect modified by the interaction process.
† The precipitant drug was defined as the drug responsible for affecting the pharmacologic action or the pharmacokinetic properties of the object drug.