Drug interactions

Question 1

_______ has been shown to increase the 1/2 life of the penicillins by inhibiting tubular secretion

Answer 1

Probenecid

Question 2

Both carboxypenicillins and ureidopenicillins have been shown to inactivate ______

Answer 2

aminoglycosides. Therefore, these agents should not be mixed in the same IV solution

Question 3

Which group of penicillins have a high sodium content, and therefore should be used with caution in pts with fluid or sodium restrictions?

Answer 3

carboxypenicillins (carbenicillin and ticarcillin)

Question 4

______ has been shown to increase the 1/2 life of some cephalosporins by inhibiting tubular secretion

Answer 4

Probenecid

Question 5

Ciprofloxacin is a potent inhibitor of this cytochrome system

Answer 5

P 450 (CYP) 1A2 isoenzyme and may increase the effect of other medications, including theophylline, warfarin, tizanidine, propranolol, and others

Question 6

If given concomitantly with fluoroquinolones, these substances will decrease the absorption of the FQs. Therefore, these agents should be separated when administered orally

Answer 6

antacids, sucralfate, and magnesium, calcium, or iron salts

Question 7

Erythromycin and Clarithromycin are potent inhibitors of the CYP3A4 isoenzyme. When administered concomitantly they have been shown to prolong the 1/2 life an extensive list, including:

Answer 7

cyclosporine, tacrolimus, carbamazepine, theophylline, warfarin, and most statins

Question 8

How well do the aminoglycoside bind to proteins?

Answer 8

Weakly (10%). They freely distribute into extracellular fluid. Approx. vol of distr: 0.25 L/kg, which may be significantly affected in intensive care pts, and in states of malnutrition, obesity, and ascites

Question 9

Aminoglycosides: bactericidal or bacteriostatic?

Answer 9

Bactericidal – drug concentration