Effect of Therapeutic Plasma Exchange on Itraconazole Pharmacokinetics: A Case Study

The authors present the case of a 34-year-old male patient who underwent therapeutic plasma exchange (TPE) for amyopathic dermatomyositis. Immunosuppression resulted in Aspergillus lentulus pulmonary infection, requiring treatment with super bioavailable-itraconazole. Therapeutic itraconazole concentrations were attained after 2 weeks of treatment after dose adjustments. Interestingly, a substantial reduction in plasma itraconazole concentration was observed during TPE, which was attributed to an insufficient delay between the dosing of itraconazole and TPE initiation. Furthermore, there was an increase in plasma concentration post-TPE, which presumably reflects the redistribution of itraconazole from peripheral compartments back into plasma. This was confirmed by sampling of the TPE plasmapheresate, which revealed that changes in plasma concentration overestimated itraconazole clearance. These findings highlight that the pharmacokinetics of itraconazole are altered during TPE, which should be considered when timing drug administration and obtaining plasma concentrations.