Many commonly used medications have been introduced in clinical care with a simple dosing regimen whereby all patients are treated with the same dose or, in the minority of cases, a simple dosing algorithm. Unfortunately, for the majority of drugs, this approach ignores important variations in individual patients’ physiologies which can severely affect the dosing requirements or the drug’s efficacy and safety profile. With an improvement in our understanding of the clinical, physiological and pharmacological factors associated with drug response in a specific patient population, we can create algorithms that can be used to individualize treatment regimens to maximize efficacy and reduce risks of adverse effects.
The case of heparin use in children undergoing cardiac surgery is particularly interesting in this regard. Currently, the dose of heparin in these patients is calculated with the assumption that 1 unit of heparin will produce 1 unit of anticoagulation. Unfortunately, in children 1 unit of heparin can produce anywhere from 0.5 to 4.0 units of anticoagulation. Too low anticoagulation and these patients can develop thrombosis, too high anticoagulation and they bleed. Either of those complications can be life threatening. My research specifically investigates the complex factors associated with heparin response in children and develops new models that can be used to predict the correct dose of heparin any individual patient needs. In the next few years, the algorithm we developed to individualize heparin dosing will be tested in clinical care and the methodology we developed will be adapted for the many other clinical situations facing a similar predicament.