Karnataka PGET 2007 Pharmacology MCQ Answer 12

The correct answer is C

The first-generation cephalosporins are Cephaloridine, Cephalothin, Cephapirin, Cefazolin, and Cephradine. Cefazolin is the most commonly used first-generation cephalosporin with a half-life of 2-hours because of its rapid excretion by the kidneys. The other first-generations have similar efficacy to Cephalexin, but must be dosed more often, and are therefore not as common.

The second-generation cephalosporins are Cefoxitin, Cefamandole, Cefaclor, and Cefuroxime. Cefoxitin is unique among the second-generation cephalosporins because it is active against B. fragilis group, but has poor gram-positive activity.The second-generation cephalosporins are used for broader gram-negative control, including coverage for B-lactamase-producing H. influenzae. They are less effective than the first-generations in covering Staph. aureus and other gram-positive organisms.

Third-generation cephalosporins display an extended gram-negative spectrum at the expense of decreased activity against gram-positive bacteria. They are often used for treating gram-negative sepsis, as several cross the blood-brain barrier (cefotaxime, ceftizoxime, ceftriaxone). These drugs are also used in treating pseudomonal infections (cefoperazone, cefpiramide, cefsulodin, ceftazidime). Cefoperazone, cefmenoxime, and moxalactam are associated with coagulation problems and disulfiram reactions. Moxalactam is associated with a ten- to one hundred-fold risk of hemorrhagic complications, so bleeding complications should be suspected when using this drug.

The fourth generation cephalosporin currently on the market is cefepime. It has the broadest spectrum activity of all the cephalosporins. It has activity against gram-negative organisms, especially pseudomonas, yet keeps activity against gram-positives including Staph. aureus. It is an excellent drug in the treatment of hospital-acquired pneumonias. Cefepime penetrates the blood-brain barrier and is eliminated in urine. Adverse reactions are similar to the above cephalosporins.

Category: Karnataka PGET 2007 MCQs