Eight Quick Tips on Inferring Antibiotic Susceptibility Results

Photo courtesy Nathan Reading (Staphylococcus aureus - Inducible Macrolide Resistance)

Antibiotic susceptibility testing is commonly used to select appropriate antimicrobial therapy or deescalate to a narrower spectrum agent.  Because not every antibiotic is tested, clinicians must infer certain types of antibiotic susceptibility based on bacterial patterns of resistance and sensitivities of other antibiotics.

The following are 8 quick tips regarding inferred antibiotic susceptibility, which are based on the EUCAST clinical breakpoints document (see references). Continue reading →

Opioid Conversion Calculator – Now Available

Opioid conversion calculator screenshotConverting between equianalgesic opioid dosing isn’t exactly a hard science.  Given the lack of blinded trials, bidirectional conversions, dose-dependent conversions, incomplete cross-tolerance, equianalgesic discrepancies in the literature, and patient-specific factors (specifically metabolism and absorption), a “simple” equianalgesic conversion table often doesn’t do the process justice. Continue reading →

WARFASA Trial – Aspirin for VTE Prophylaxis

Mufasa from the Lion King

The WARFASA trial, recently published in the NEJM, examined the role of aspirin after patients with VTE’s had completed 6-18 months of warfarin therapy.  Given the safety of the treatment and the impressive reduction in VTE recurrence, it’s very likely that the results of the  WARFASA trial will find their way into the next CHEST guideline updates. Continue reading →

Drug Dosing in Obesity Reference Table – Now Available!

Dosing weight-based medications in obese patients can often be a tricky proposition. Most medications do not have guidelines for morbidly obesity, forcing clinicians to pursue in-depth literature searches in order to decide on a dose.  This is not only time consuming, but not having an accurate idea of how to dose a medication can be a problem with patient safety.

For the newest addition to ClinCalc, I have created a Drug Dosing in Obesity Reference Table page that will serve as a dynamic growing repository of evidence-based recommendations regarding medication dosing in obese patients.  Enjoy! Continue reading →

Aminoglycoside Calculator – Now Available!

Aminoglycosides have a narrow therapeutic window necessitating therapeutic drug monitoring for safe and effective use.  Either fortunately or unfortunately, their use has fallen out of favor and many clinicians are now less familiar with dosing these agents.  Combining unfamiliarity with complex pharmacokinetic calculations, the risk of medication errors with aminoglycosides is extremely high.  For these reasons, I have developed a new addition to ClinCalc — the aminoglycoside calculator. Continue reading →

Vancomycin AUC:MIC versus T>MIC

There is a significant amount of controversy regarding the most appropriate therapeutic goal for vancomycin therapy. The difference of opinion stems from the pharmacodynamic activity of vancomycin.

Definitions

  • MIC (minimum inhibitory concentration) – The minimum concentration of antibiotic to inhibit the growth of an organism.
  • AUC (area under the curve) – The total exposure of an antibiotic to an organism Continue reading →

Ideal Body Weight Calculator – Now Available!

Ideal body weight and other body weight measures are widely used for a variety of medical purposes, including drug dosing, renal function, categorizing obesity, and dosing chemotherapy.  The newest ClinCalc, the Ideal Body Weight Calculator, is capable of providing results and equations for the following body weight metrics:

  • Ideal body weight (based on the Devine 1974 equation)
  • Adjusted body weight (if obese)
  • Nutritional body weight (for dosing enteral/parenteral feeds)
  • Lean body weight (based on the LBW2005 equation)
  • Body mass index
  • Body surface area

Continue reading →

Top 10 Facts about Creatinine Clearance … and a New ClinCalc

Evaluating renal function for the purposes of drug dosing is a common task for clinical pharmacists, but a number of misconceptions have developed over the past forty years as the process of evaluating renal function has improved.  The following are the top 10 facts that every clinician should know about creatinine clearance:

  1. Cockcroft-Gault is still the best equation for renally adjusting medications.  Although the Cockcroft-Gault equation is less accurate than newer methods (MDRD and CKD-EPI) for estimating renal function, drug manufacturers typically use the older C-G method to determine renal adjustments of medications.  Currently, the National Kidney Foundation recommends MDRD/CKD-EPI for evaluating the progression of renal function, and C-G for dosing medications. Continue reading →