The antibiotic knowledge survey of our new interns this week, showed that many were confused about which class vancomycin (a glycopeptide) fell into (30% thought it was an aminoglycoside). This is a potentially dangerous confusion as the dosing, side effects and monitoring all differ substantially between these classes:
|Dosing||By ideal body weight (IBW) if actual weight > 20% over IBW||Actual weight ( see below)|
|Loading dose||No (higher dose in severe sepsis)||Yes|
|Monitoring||Not required for short course (3 daily dose) therapy||Yes (just prior to 4th dose)|
Ototoxicity (idiosyncratic and cumulative)
|Renal (associated with sustained levels above 25mg/L)
Ototoxicity possible but rare
|AIMED postings of relevance||Safe use of aminoglycosides||Dosing of vancomycin in obese patients|
The schema below worthy of further study! Particularly focus on betalactams, aminoglycosides, glycopeptides, sulphonamides, tetracyclines and quinolones to start with. This antimicrobial agent study proforma is a useful way to start documenting your knowledge.
An important aspect of antibiotic allergy surrounds the betalactam class – see these postings for useful allergy explanations from our experts.
The current Therapeutic Guidelines: Antibiotic is a useful starting point – look to the introductory chapter and the appendices on aminoglycosides and vancomycin. However, as a prescriber, you will need to know more than that !