FPGEE for National Association of Boards of Pharmacy (NABP) Practice Exam

Which of the following statements is true regarding Group II antibiotics?

1. They have concentration-dependent kill rates

2. They exhibit no post-antibiotic effect

3. They require maintaining serum levels above MIC

4. They should be given as a single large dose

The correct answer is: They require maintaining serum levels above MIC

Group II antibiotics, which include examples like aminoglycosides, have specific pharmacokinetic properties that influence their usage and dosing strategies. The correct answer emphasizes the necessity of maintaining serum drug levels above the minimum inhibitory concentration (MIC) to ensure efficacy against bacteria. MIC is the lowest concentration of an antibiotic that prevents visible growth of a bacterium. By ensuring that serum levels are sustained above this threshold, the antibiotic can effectively suppress bacterial growth and allow for a more prolonged effect. This concept is particularly important in the context of treating infections, as below MIC levels can lead to treatment failure and contribute to the emergence of resistance. Therefore, achieving and maintaining serum levels that exceed the MIC is crucial for the success of therapy when using these antibiotics. The other options do not accurately reflect the characteristics of Group II antibiotics. For instance, concentration-dependent killing is not a distinguishing feature exclusive to this group; certain antibiotics across various classifications exhibit this property. Similarly, some antibiotics do demonstrate a post-antibiotic effect, which relates to the continued suppression of bacterial growth even after the drug concentration falls below the MIC. Lastly, while certain antibiotics may be administered in large doses, this is not a requirement that applies universally to Group II antibiotics. Each antibiotic within this group is best