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Table 3 Summary of interacting drug pairs with a potential for clinical significance—major and contraindicated drug interactions

From: Polypharmacy and the occurrence of potential drug–drug interactions among geriatric patients at the outpatient pharmacy department of a regional hospital in Durban, South Africa

Interacting drug pairs Mechanism of action Frequency Percentage
Major drug interactions PD/PK/UNK n = 349 %
Paracetamol Carbamazepine PK 50 14.3
Amlodipine Simvastatin PK 43 12.3
Ferrous sulphate Lansoprazole PK 33 9.5
Carbamazepine Simvastatin PK 26 7.4
Allopurinol Aspirin PD 24 6.9
Aspirin Naproxen PD 23 6.6
Lansoprazole Naproxen PD 20 5.7
Amitriptyline Tramadol PD 17 4.9
Aspirin Clopidogrel PD 13 3.7
Carbamazepine Tramadol PK 13 3.7
Atenolol Naproxen PD 12 3.4
Hydralazine Tramadol PD 10 2.9
Fluconazole Simvastatin PK 8 2.3
Aspirin Warfarin PD 5 1.4
Contraindicated drug interactions PD/PK/UNK n = 8 %
Amitriptyline Potassium Chloride PK 1 12.5
Desmopressin Hydrocortisone PD 1 12.5
Tamoxifen Warfarin UNK 1 12.5
Fluconazole Tramadol PK 5 62.5
  1. PD pharmacodynamic, PK pharmacokinetic, UNK unknown