Aim Current prescribing in our trust, in the absence of a guideline and licensing for prophylactic posaconazole in children under 12 years, is based on a paper by Boonsathorn et al. 2018 ¹ The purpose of this audit is to evaluate the extent to which prescribing and monitoring of prophylactic oral posaconazole prescribed within our paediatric inpatient population is in line with published recommendations.¹ Targets were 100% of patients were dosed as recommended¹; 100% of trough concentrations for posaconazole were taken within 5–10 days after initial administration; and if trough concentrations are not in range (>0.7 mg/L) was corrective action taken.

Method Patients between the ages of 2 months to 12 years with primary immunodeficiency recorded on their health record as being initiated on prophylactic posaconazole in the last 2 years were identified. Where patients met the inclusion criteria; age, weight, posaconazole formulation, date of initiation of posaconazole, trough concentration, date of trough concentration and dose adjustments were collected. Data was collated and analysed using MS Excel. Caldicott Guardian approval (ID: 9378) was granted by our trust and was added to the clinical effectiveness register (ID: 13451).

Results 23 patients were included with the mean age of 3.7 years. 84% of patients were dosed as recommended by Boonsathorn et al. 52% of all patients got a trough concentration taken within the 5–10 days and 75% of those patients had a trough concentration of >0.7 mg/L. 25% of patients had concentrations taken in 5–10 days that were <0.7 mg/L and doses were increased. These increased doses were not as recommended.¹ 33% of patients had concentrations taken in 5–10 days that greatly exceeded 0.7 mg/L and had dose reductions.

Conclusion The majority of the patients were dosed as recommended and had a trough concentration >0.7 mg/L. Recommendations could be translated into a guideline to include; advising trough concentrations are taken 5–10 days of initial administration to get an accurate picture of the posaconazole concentration. To include recommendations of dose adjustments following <0.7 mg/L trough concentrations to get consistent optimal prescribing. There was no maximum trough concentration for prescribers to adhere so the addition of a maximum trough concentration and recommendations of dose reductions would improve the clinical safety of prescribing prophylactic posaconazole. Limitations of this audit included the limited number of patients that fitted the criteria and results cannot be generalised for all oral formulations as only one patient was prescribed tablets.

Reference

1. Boonsathorn, S, Cheng I, Kloprogge F, et al. Clinical pharmacokinetics and dose recommendations for posaconazole in infants and children. Clinical Pharmacokinetics 2018;58:53–61.