Table 5.

Description of the top-20 and clinically important potential drug–drug interactions in patients with pneumonia

Interacting pairs	Frequency	Severity	Documentation	Potential adverse outcomes
Aspirin – Furosemide	40	Major	Good	Reduced diuretic effectiveness and possible nephrotoxicity
Furosemide – Hydrocortisone	39	Moderate	Fair	Hypokalemia
Aspirin – Clopidogrel	37	Major	Fair	Increased risk of bleeding
Aspirin – Insulin	33	Moderate	Fair	Hypoglycemia
Isoniazid – Rifampin	33	Major	Good	Hepatotoxicity
Calcium containing products – Ceftriaxone	33	Contraindicated	Good	Formation of ceftriaxone-calcium precipitates and is contraindicated in neonates
Pyrazinamide – Rifampin	32	Major	Good	Hepatotoxicity
Aspirin – Ramipril	28	Moderate	Fair	Decreased ramipril effectiveness
Albuterol – Furosemide	28	Moderate	Fair	ECG changes or hypokalemia
Aspirin – Bisoprolol	23	Moderate	Good	Increased blood pressure
Furosemide – Ramipril	23	Moderate	Good	Postural hypotension (first dose)
Clarithromycin – Dexamethasone	23	Major	Fair	Decrease clarithromycin exposure and increased dexamethasone exposure
Aspirin – Dexamethasone	21	Moderate	Good	Increased risk of gastrointestinal ulceration and subtherapeutic aspirin serum concentrations
Aspirin – Nitroglycerin	20	Moderate	Good	Increase in nitroglycerin concentrations and additive platelet function depression
Clopidogrel – Esomeprazole	17	Major	Excellent	Reduced plasma concentrations of clopidogrel active metabolite and reduced antiplatelet activity
Azithromycin – Moxifloxacin	16	Major	Fair	Increased risk of QT-interval prolongation
Aspirin – Spironolactone	16	Major	Good	Reduced diuretic effectiveness, hyperkalemia, or possible nephrotoxicity
Clopidogrel – Omeprazole	13	Major	Excellent	Reduced plasma concentrations of clopidogrel active metabolite and reduced antiplatelet activity
Omeprazole – Rifampin	13	Moderate	Fair	Decreased omeprazole plasma concentrations
Ramipril – Spironolactone	13	Major	Good	Hyperkalemia