Aim The trust has implemented the use of therapeutic drug monitoring (TDM) of teicoplanin on intensive care following research that identified great variability in population pharmacokinetics in children.^1–3 The summary of the research available showed that patients are not achieving target concentrations. This retrospective audit aimed to evaluate whether patients were achieving target serum concentrations. It also evaluated whether teicoplanin TDM was correctly completed for each patient. The following objectives were set based on grey literature and the Summary of Product Characteristics:⁴ Evaluate if serum concentrations are being taken on or after day 4 post initiation (steady state), and within 1 hour pre-dose (trough) Assess if serum concentrations reach target concentration with standard initial BNFC dosing appropriate for the indication of treatment.

Methods A retrospective report of teicoplanin serum concentrations was provided by the biochemistry labs covering a 6 month period. This report was used to identify the patients for the audit. For each patient: dose information, times and clinical particulars were obtained via the electronic prescribing system, Meditech version 6. If needed, clinical records were obtained from the medical records archive.

Results 71 serum concentrations were identified. 11 were excluded due to unobtainable or incomplete data. Serum concentrations were then evaluated for accuracy. The criteria set for determining accuracy were: Serum concentration taken on or after day 4 post initiation (steady state) Serum concentration taken within 1 hour pre dose (trough) Patient prescribed correct BNFC dosing regimen 55% (n=33) of patients had all 3 criteria met for an accurate concentration to be determined. This meant 45% of our patients serum concentrations could not be used to accurately evaluate if current dosing regimens promptly achieve target concentrations. Using the patients’ serum concentrations that followed the above criteria, it was found that 64% of these patients did not reach their desired target concentration. This included patients with: endocarditis (n=5) – aiming for trough greater than 30 mg/L cystic fibrosis (n=1) – aiming for trough greater than 20 mg/L other infections such as sepsis (n=27) – aiming for trough greater than 15 mg/L No patient included in this audit that required a higher target concentration reached their target before the first serum concentration.

Conclusion It is evident that teicoplanin TDM, which is still in its infancy at the trust, requires further support to improve practice. From the serum concentrations that were carried out correctly, this audit begins to illustrate a number of issues surrounding teicoplanin dosing in paediatric patients, especially those with difficult to treat infections. Further research is required to assess how these correlate to clinical outcome in practice as well as evaluating patients not in an intensive care setting. This study can be a driving force for a larger scale study to be carried out so that recommendations can be established and a change of practice can be implemented.

References

1. Ramos-Martín V, Paulus S, Siner S, et al. Population Pharmacokinetics of Teicoplanin in Children. J Antimicrob. Chemother 2014;58: 6920–6927

2. Harding I, Macgowan AP, White LO, et al. Teicoplanin therapy for Staphylococcus aureus septicaemia: relationship between pre-dose serum concentrations and outcome. J. Antimicrob. Chemother 2000;45:835–841.

3. Reed MD, Yamashita TS, Myers CM, et al. The pharmacokinetics of teicoplanin in infants and children. J. Antimicrob. Chemother 1997;39:789–796.

4. Targocid 400mg [Internet]. Targocid 400mg - Summary of Product Characteristics (SmPC) - (eMC). Available from: https://www.medicines.org.uk/emc/product/2927 (Accessed 20 February 2018)