Question 19

Describe the mechanism of action, dose, pharmacokinetics and pharmacodynamics of ceftriaxone.

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College Answer

A structured answer under the headings of mechanism of action, dose, pharmacokinetics and pharmacodynamics worked most effectively for this question. It was expected that candidates would link the mechanism of action of Ceftriaxone (binds to PBP and inhibits final step in peptidoglycan) to its spectrum of activity. Dosing would also include indications for higher dosing, and consideration of the fact that ceftriaxone is available as an IM administration. Details on hypersensitivity (fever, nephritis, haemolytic anaemia) and consideration of C.diff infection was a main part of its pharmacodynamics. For pharmacokinetics, a structural approach is recommended, important points included excretion through both kidneys and bile and absence of liver metabolism.

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