Comparative Pharmacology of Antibiotics
Both Question 3 from the second paper of 2006 and Question 9 from the second paper of 2003 asked the candidates to compare and contrast the pharmacology of ceftriaxone, gentamicin and meropenem. The answer to this specific question comes first in this chapter. It is not followed by a more indepth discussion of antibiotic pharmacology, because this would be something of a waste. it is unlikely that - after nine years of neglect - the college would bring this sort of question back into the papers.
A comparison of the selected antibiotics which the college was interested in:
|
|
Ceftriaxone |
Gentamicin |
Meropenem |
|
Class |
3rd gen cephalosporin |
Aminoglycoside |
Carbapenem |
|
Administration |
IV – 1g; up to 3g/day |
IV; daily dosing 5-7mg/kg |
IV 1-2g – up to 6g/day |
|
Pharmacokinetics |
Cleared both renally (unchanged) and via biliary excretion (33%) |
Cleared renally; rapidly and unchanged |
Cleared renally |
|
Mechanism of action |
Inhibition of bacterial cell wall synthesis by binding to penicillin-binding proteins |
Inhibition of bacterial protein synthesis by binding to the 30S subunit of the bacterial ribosome |
Inhibition of bacterial cell wall synthesis by binding to penicillin-binding proteins |
|
Indications |
Infections by susceptible gram-positive organisms; |
Infections by susceptible gram-negative organisms; |
Infection by susceptible gram-positive and gram negative aerobic and anaerobic organisms; broad cover |
|
Precautions |
Seizures in overdose |
Nephrotoxicity |
Seizures in overdose |