Question

1. Give at least 12 common drug-drug interactions with their corresponding result when taken concomitantly.

Answer 1

Sr. No.	Drug	Drug	Result when taken concomitantly
1	Probenecid	Penicillin	Tubular secretion of penicillin inhibited, prolong antibiotic action of penicillin
2	Allopurinol	Ampicillin	Increased risk of rashes
3	Metronidazole	Warfarin	Metabolism of warfarin inhibited and increases bleeding time
4	Iron salts	Tetracyclines	Decreases absorption of tetracycline by formation of complexes
5	Furosemide	Minocycline	Increases vestibular toxicity
6	Tetracycline	Penicillins	Bactericidal action of penicillin may be antagonized
7	NSAIDs	Ciprofloxacin	Increases CNS toxicity and seizures
8	Sildenafil	Isosorbide mononitrates	Potentiation of effect, lead to fall in BP
9	Potassium chloride	Spironolactone	Hyperkalemia may occur as both increases the level of potassium
10	Clonidine	Propranolol	Produces hypertension
11	Warfarin	Diflunisal	Increases risk of gastrointestinal bleeding by increasing anticoagulant response of warfarin
12	Methotrexate	Probencid	Increase in the level of methotrexate as elimination rate is reduced, and increases action to 2 – 3 fold and causing toxicity that include symptoms like diarrhea, vomiting, renal failure and it may be fatal.
13	Digoxin	quinidine	Increases digoxin level in plasma as quinidine decreases renal and nonrenal excretion of digoxin, digoxin has very low therapeutic index and increases in the level may cause digoxin toxicity.