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Table 6 Common pDDIs of prescriptions dispensed at SPC Anuradhapura 2015

From: Drug utilization, prescription errors and potential drug-drug interactions: an experience in rural Sri Lanka

Combination (%) Mechanism of pDDI according to the Medscape drug interaction checker [21]
Serious (Total = 94)
 Methotrexate-Leflunomide (6.4) Leflunomide increases toxicity of methotrexate by pharmacodynamic synergism.
 Meloxicam-Methotrexate (5.3) Meloxicam increases levels of methotrexate by decreasing renal clearance.
 Clopidogrel-Omeprazole (5.3) Omeprazole decreases effects of clopidogrel by affecting hepatic enzyme CYP2C19 metabolism.
 Clopidogrel-Esomeprazole (5.3) Esomeprazole decreases effects of clopidogrel by affecting hepatic enzyme CYP2C19 metabolism.
 Atorvastatin-Vitamin B3 (5.3) Either increases toxicity of the other by pharmacodynamic synergism.
 Atorvastatin-Fenofibrate (5.3) Either increases effects of the other by pharmacodynamic synergism.
Significant (Total = 1017)
 Aspirin-Losartan (5.5) Aspirin decreases effects of losartan by pharmacodynamic antagonism. losartan and aspirin both increase serum potassium.
 Losartan-Frusemide (3.2) Losartan increases and furosemide decreases serum potassium.
 Aspirin-Clopidogrel (3.0) Either increases toxicity of the other by pharmacodynamic synergism.
 Clopidogrel-Pantoprazole (2.3) Pantoprazole decreases effects of clopidogrel by affecting hepatic enzyme CYP2C19 metabolism.
 Celecoxib-Diclofenac sodium (2.0) Celecoxib and diclofenac both increase anticoagulation and serum potassium.
 Aspirin-Frusemide (2.0) Aspirin increases and furosemide decreases serum potassium.
Minor (Total = 265)
 Glipizide - Sitagliptin (7.6) Either increases effects of the other by pharmacodynamic synergism.
 Metformin - Vitamin B12 (5.7) Metformin decreases levels of cyanocobalamin by unspecified interaction mechanism.
 Metformin-Frusemide (3.8) Metformin decreases levels of furosemide by unspecified interaction mechanism. Furosemide increases levels of metformin by unspecified interaction mechanism.
 Methotrexate - Folic acid (3.4) Folic acid decreases effects of methotrexate by pharmacodynamic antagonism.
 Aspirin-Diltiazem (2.6) Diltiazem increases effects of aspirin by unknown mechanism.
 Metformin-Hydrochlorothiazide (2.6) Hydrochlorothiazide will increase the level or effect of metformin by basic (cationic) drug competition for renal tubular clearance. Hydrochlorothiazide decreases effects of metformin by pharmacodynamic antagonism.