Effect of posaconazole on cyclosporine blood levels and dose adjustment in allogeneic blood and marrow transplant recipients.

The posaconazole prescribing information recommends an upfront cyclosporine dose reduction upon initiation of posaconazole prophylaxis. We examined this recommendation in the early phase of allogeneic transplantation, where cyclosporine levels potentially becoming subtherapeutic following upfront dose reduction would be deleterious to transplant outcome. Our data show that while posaconazole leads to an increase in cyclosporine levels, subsequent cyclosporine dose reduction can be safely guided by therapeutic drug monitoring and is not required upfront. Therefore, the current recommendation may be modified.