Could Physician Education and Application of Pharmacokinetic Principles Improve Serum Gentamicin Levels in Neonates?
Gladys El-Chaar, College of Pharmacy & Allied Health Professions, Department of Clinical Pharmacy Practice
Background: Therapeutic Drug Monitoring (TDM) is an important tool in devising individualized drug dosing based on pharmacokinetic (PK) calculations. TDM is especially important in neonates given their variable and dynamic physiological states. Pharmacotherapists usually perform TDM; however, when not available, physicians often do not attempt such calculations. A PK education and training program was implemented to teach physicians to perform PK calculations and dosage changes. There are scant data addressing physician education regarding application of PK on drug levels.
Objective: To ensure accuracy of PK calculations and dosage changes made by physicians after the educational program and identify barriers in physician PK-derived dosage changes. We hypothesized that TDM performed by physicians after the educational program will result in a greater number of maximum serum (Cmax) gentamicin levels in the therapeutic range.
Design/Methods: This retrospective chart review included neonates who received gentamicin and had elevated trough serum gentamicin concentrations (SGC) 6 months before and 6 months after implementation of a PK training program to physicians. Trough SGC were used to calculate gentamicin Cmax. Before PK training, dosage changes made by physicians were done by fixed percentages and calculated Cmax levels after these dosage changes were expected to be low. Didactic workshops and one-on-one sessions by the pharmacotherapist were carried out to teach PK-derived dosage calculations. We analyzed the differences in calculations of PK parameters and dosage changes between the pharmacotherapist and physicians after training. A survey was distributed to identify barriers to the physician PK-derived method of dosage adjustments. A sample size of 39 patients in each group was needed to reduce the sub-therapeutic gentamicin Cmax from 50% to 20% with 80% power and a 5% level of significance.
Results: There were 41 courses of gentamicin in each group. Before training, only 26% of calculated Cmax levels were in the therapeutic range. After PK training, this number rose to 100% (p=0.0001). Pharmacokinetic calculations and dosage changes performed by physicians were done correctly. Most common barriers to PK-derived dosage calculations were time to perform calculations and delay in laboratory reporting of SGC.
Conclusions: PK education of house-staff education was successful and resulted in improved gentamicin levels.