Optimizing the oral dose of cyclosporine with concomitant posaconazole post stem cell allograft

Cyclosporine is an immunosuppressive agent to prevent acute graft versus host disease (GVHD) in patients undergoing a stem cell allograft. It has a narrow therapeutic range, and its metabolism can be affected by posaconazole, commonly used as antifungal prophylaxis post allograft. There is limited evidence on the optimal oral cyclosporine starting dose in this setting. A delicate balance is required in dose adjustments to avoid toxic levels while maintaining sufficient drug concentrations to prevent GVHD. We undertook a retrospective audit of 28 patients undergoing their first allograft who received posaconazole and commenced on a starting oral cyclosporine dose of 2 mg/kg twice daily. Our key findings were that this starting dose was too high, with all patients experiencing at least one toxicity and an overall low incidence of GVHD.