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Concerns: Aminoglycosides and Vancomycin in Renal Failure

Concerns: Aminoglycosides and Vancomycin in Renal Failure
Welcome everybody to the class. This is Dr. Lee from Taipei Medical University. The topics today is aminoglycoside and vancomycin in renal failure. Why specifically aminoglycoside and vancomycin in renal failure? There are three major concerns. First both are known for their adverse effect of nephrotoxicity and the ototoxicity and both are extensively excreted by the kidneys. And both represent the gold standard of therapeutic drug monitoring. And this slide show the chemical structures of aminoglycosides and the vancomycin aminoglycoside here we have two homologs gentamicin and tobramycin. Vancomycin is a glycopeptide is really not an aminoglycoside but they are covered side by side in light of their similarities and differences.
So let’s look at the similarities and the differences between aminoglycoside and vancomycin in terms of chemistry, aminoglycoside, well are aminoglycosides vancomycin is a glycopeptide half-life aminoglycoside have short half-life vancomycin has relatively long enough. Volume distribution. Both have small volume distribution. However aminoglycoside is point three liter per kilogram. Vancomycin is relatively large at about one liter per kilo fraction of the drug excreted and changed both have greater than 80 percent. Toxicity both nephrotoxic and ototoxic anti-microbial effect aminoglycoside are for gram-negative and vancomycin is for gram-positive. Bacteriacidal effect.
Aminoglycoside is concentration-dependent that means the killing of the bacteria is dependent on a large concentration not it the C max of the gentamicin concentration For example, vancomycin on the other hand, is time-dependent that means the bacteria-killing depends on the time exposure that is the area under the curve instead of C max. Toxicities. The toxicities result from the accumulation of both drugs over time. Nephrotoxicity is a greater concern because aminoglycoside and vancomycin are both excreted to an large extent by the kidneys Nephrotoxicity in a renal failure can form a vicious cycle exacerbating the detrimental effect Furthermore, combination with other drugs increases the potential for nephrotoxicity such as amphotericin or thiazide diuretics.
So as a pharmacist, do ask the patient about any medications that they are taken. This is worse The advanced age increases the potential for toxicity. So for older people, we ought to pay special attention to them. So in the following few slide, I’m gonna reveal the kinetics of intermittent infusion because intermittent infusion is how these drugs are given. Let’s say after a single infusion at the constant rate. This is what the plasma profile looks like At the end of infusion you have peak concentration and at the end of infusion you have trough concentration and here the infusion time is one hour and the dosing interval is twelve hours

In this step, Prof. Lee explains the 3 major concerns on using Aminoglycosides and Vancomycin in renal failure.

The first one is the toxicity. Both of them are known for adverse effects of nephrotoxicity and ototoxicity, which can be demonstrated by their structures.

The second one is where they are excreted. Both of them are extensively excreted by the kidneys.

Finally, they both represent the gold standard of therapeutic drug monitoring. Thus, we should pay attention to their serum concentration.

Besides, we can know their characteristics from the comparison table in this video, including their half-life, Volume of Distribution, and toxicity.

Ultimately, we can learn the intermittent infusion from this video. We should know how to calculate the dosing interval, and the meaning of peak and trough.

If you have any questions or thoughts, please share them below.

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Pharmacokinetics: Drug Dosing in Renal Disease

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