DOI: 10.1097/FTD.0b013e3181fd4c42
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PMID: 21233691
Issn Print: 0163-4356
Publication Date: 2011/02/01
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Excerpt
With interest I have read the article of Aubert and colleagues1 on the prospective determination of serum ceftazidime (CAZ) concentrations in intensive care units (ICUs). The authors conclude their article by stating that CAZ measurement is needed in ICUs to achieve adequate CAZ concentrations to reach optimal efficacy and minimal toxicity. I agree with the authors that in an ideal world, it would be great to have an opportunity to optimize our treatment by measuring the concentration of a drug used if there is a clear relationship between the pharmacokinetics and pharmacodynamics of the drug as clearly is the case in the treatment of many infectious diseases. However, in the case of CAZ, an antibacterial agent purely cleared by glomerular filtration rate (GFR), the question arises whether it would have been much easier to measure GFR than to measure CAZ.
In their “Materials and Methods” section, the authors mention that patients received a loading dose of 2 g followed by a continuous infusion of 2 to 6 g depending on creatinine clearance, patient weight, and severity of the infection. More importantly, they report that the dosing of CAZ in the individual patient was at the discretion of the treating physicians! In other words, it seems that dosing was not based on the clearing capacity of the individual patient as could have been determined by the determination of the GFR, but more dependent on the experience and personal taste of the individual physician. Therefore, I would like to ask the authors to provide in their reply to this letter more detailed information on the dosing used in patients with different GFR values. That kind of information might give much more insight into what really happened than the information currently provided in Table 1.
In addition, it would be of major value for the readership of the journal if the authors could provide more information on the total body clearance of CAZ in relation to the GFR. Based on the data they collected, this should be possible and would provide a better rationale whether to determine CAZ concentrations in these patients or to just measure GFR to guide the dosing of CAZ in these sick patients.
Finally, I would like to convince the authors that if indeed there is a clear relation between GFR and CAZ in their patients, it will be much more feasible for other ICUs to calculate or measure GFR and not to develop and validate an assay for CAZ. Moreover, it might be very useful to use real creatinine clearance as a marker of GFR in the ICU (collecting 24-hour urine is not a problem in that setting) and see if the relation between CAZ clearance and real GFR is even more tight and therefore more useful for clinicians and pharmacists to provide more personalized care for their ICU patients.
