Online dose calculation tool for determining dosing regimens in the very young

Few tools are available to quickly calculate dose in neonates. A dosing calculator has been developed using age, weight and renal function. The aim of this calculator is to provide quick and accurate predictions of average steady state concentration (Csspred) and expected time course for a range of dosing regimens in neonates.

The dosing calculator has been implemented using an existing pharmacokinetic model for vancomycin PK (1) that relies on maturation and allometric scaling principles (2). It can be readily extended to other medicines. In its current form, the calculator can be accessed with a web browser and run on any computer or mobile operating system that is capable of running Adobe Flash Player® 10. The user interface was constructed with Adobe Flash® and Adobe Actionscript® 3.0, which is based on the Java programming language. A mobile version will be developed for use specifically on popular mobile devices (e.g. iPhone, BlackBerry).

Clearance and volume of distribution are estimated based on input age, weight and renal function. If weight is not known it can be estimated from age alone. The calculator generates a plot of Csspred according to age and any given dosing regimen and compares this to an individual’s Csspred. It also plots an individual’s concentration time course. It is important that the dosing calculator is accurate, usable and provides the right information. At this stage of development, we are seeking input and feedback from paediatric clinicians and clinical pharmacologists at other institutions.

  1. Anderson BJ, Allegaert K, Van den Anker JN, Cossey V, Holford NH. Vancomycin pharmacokinetics in preterm neonates and the prediction of adult clearance. Br J Clin Pharmacol. 2007 Jan;63(1):75-84.
  2. Anderson BJ, Holford NHG. Mechanistic basis of using body size and maturation to predict clearance in humans. Drug Metab Pharmacokinet. 2009;24(1):25-36.

Sam Holford

Hi, I'm the PAGANZ web guy and an Obstetrics & Gynaecology registrar at Middlemore Hospital. I dabble in the practical aspects of improving dosing through development of NextDose.