20
Table 3. Commonly Encountered Drug-Drug Interactions
During Treatment of Aspergillosis
Agent/Class Interaction Comment
Calcineurin inhibitors
(CNI) and mammalian
target of rapamycin
inhibitors (mTOR)
immunosuppressive agents
Significant increase in
CNI levels by azole
• CNI and mTOR agents
should be reduced (~30–
50% for CNI and more
for rapamycin) at the time
of initiating azole therapy,
and serum levels for both
agents monitored until
steady state is reached.
• Stopping of CNI or
mTOR may provoke graft
rejection.
Corticosteroids Levels are increased by
azoles
• May exacerbate immune
suppression favorable for
fungal growth.
• Prolonged co-
administration may elicit
signs of excessive steroid
exposure.
Antiretroviral agents for
HIV
Variable effects • Frequently used in
combination with other
classes of agents.
• Monitoring of azole
levels recommended, and
bidirectional drug-drug
interactions are common.
Rifampin/rifabutin Decreased levels of azole
agents while rifampin/
rifabutin levels are
increased
• Combined use
of voriconazole,
posaconazole,
isavuconazole, or
itraconazole with
rifampin/rifabutin should
generally be avoided.
• Some combinations
are considered
contraindicated; others
may be managed by TDM
and dose adjustment.
