Current Status of Therapeutic Drug Monitoring in Australia and New Zealand: A Need for Improved Assay Evaluation, Best Practice Guidelines, and Professional Development

Abstract

The measurement of drug concentrations, for clinical purposes, occurs in many diagnostic laboratories throughout Australia and New Zealand. However, the provision of a comprehensive therapeutic drug monitoring (TDM) service requires the additional elements of pre- and postanalytical advice to ensure that concentrations reported are meaningful, interpretable, and clinically applicable to the individual patient. The aim of this project was to assess the status of TDM services in Australia and New Zealand. A range of professions involved in key aspects of TDM was surveyed by questionnaire in late 2007. Information gathered included: the list of drugs assayed; analytical methods used; interpretation services offered; interpretative methods used; and further monitoring advice provided. Fifty-seven responses were received, of which 42% were from hospitals (public and/or private); 11% a hospital (public and/or private) and pathology provider; and 47% a pathology provider only (public and/or private). Results showed that TDM is applied to a large number of different drugs. Poorly performing assay methods were used in some cases, even when published guidelines recommended alternative practices. Although there was a wide array of assays available, the evidence suggested a need for better selection of assay methods. In addition, only limited advice and/or interpretation of results was offered. Of concern, less than 50% of those providing advice on aminoglycoside dosing in adults used pharmacokinetic tools with six of 37 (16.2%) respondents using Bayesian pharmacokinetic tools, the method recommended in the Australian Therapeutic Guidelines: Antibiotic. In conclusion, the survey highlighted deficiencies in the provision of TDM services, in particular assay method selection and both quality and quantity of postanalytical advice. A range of recommendations, some of which may have international implications, are discussed. There is a need to include measures of impact on clinical decision-making when assessing assay methodologies. Best practice guidelines and professional standards of practice in TDM are needed, supported by an active program of professional development to ensure the benefits of TDM are realized. This will require significant partnerships between the various professions involved.

Appropriateness of digoxin level monitoring in a childrens hospital

“…An accepted strategy to change physician behaviour is to offer educational lectures and tutorials, education is a key tool for changing physician opinions and a prerequisite to other interventions that are better for reinforcing behavior, however, this approach is labour intensive and the effect tends to decrease over time Bates, 1998). Moreover, the development of national and/or international guidelines for TDM is needed (Norris et al, 2010), especially for children, adult criteria are not suitable for children in some cases, these are likely to be accepted by clinicians if they are evidence based. Whether through education or Huang et al 2943 development of guidelines, multidisciplinary efforts play an increasing role in quality improvement, strengthening the cooperation between physicians and pharmacists to the benefit of managing TDM, the physician need to improve the quality of digoxin TDM requests.…”

Simultaneous determination of seven β-lactam antibiotics in human plasma for therapeutic drug monitoring and pharmacokinetic studies

“…For aminoglycoside antibiotics, immunochemical assays provide such an advantage. However, no such techniques are available for -lactam antibiotics and previous attempts to develop such methods have been difficult [42,43]. Most of the studies that have described TDM for these antibiotics utilized high performance liquid chromatography (HPLC) assay methods [41].…”

Bayesian Estimation of Tobramycin Exposure in Patients with Cystic Fibrosis

“…There is ongoing concern about toxicity due to the repetitive nature of tobramycin exposure (4). Bayesian methods have been used in the TDM of drugs for over 20 years; however, they are still not a commonly used strategy in the clinical setting, in particular in Australia and the United Kingdom (16,28,29). This may be attributed to a lack of one or more of the following: the availability of licensed software, the availability of skilled users, an understanding of Bayesian principles, and validation in a clinical setting.…”