Category Archives: ClinCalc News

New Calculator – Phenytoin Correction for Concurrent Valproic Acid

Phenytoin (PHT) and valproic acid (VPA) compete for the same binding sites on albumin.  In patients taking both PHT and VPA, the free fraction of phenytoin will be increased, which causes a total PHT level to falsely represent a patient’s active PHT status.

To supplement the recent video on Total vs. Free Phenytoin and the existing correction calculator for hypoalbuminemia, a new correction calculator for concurrent valproic acid has been released.

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New Statistical Calculators on ClinCalc.com

Now available on ClinCalc – sample size and post-hoc power calculators!

Sample Size Calculator

Prior to designing a trial, authors must determine how many subjects should be included in a trial in order to have adequate statistical power.  There are a variety of different equations depending on the trial design and the type of outcome being measured.  Check out the ClinCalc Sample Size Calculator.

Post-hoc Power Calculator

Following the completion of a trial, authors (or reviewers) may want to calculate the statistical power of a trial.  Although there are pitfalls in using post-hoc power analysis, which are described in the article, post-hoc power is commonly used in medical literature.  Check out the ClinCalc Post-hoc Power Calculator. 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

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