19
Antiretroviral
agents (cont'd)
CCR5 inhibitors
Maraviroc
RIF should not be used with
maraviroc. RFB can be used with
maraviroc.
Anti-infectives Macrolide antibiotics
(azithromycin,
clarithromycin,
erythromycin)
Azithromycin has no significant
interaction with rifamycins.
Coadministration of clarithromycin
and RFB results in significant
bidirectional interactions that can
increase RFB to toxic levels, increasing
the risk of uveitis.
Erythromycin is a CYP3A4 substrate;
clearance may increase in setting of
rifamycin use.
Doxycycline May require use of a drug other than
doxycycline.
Azole antifungal
agents (ketoconazole,
itraconazole,
voriconazole,
fluconazole,
posaconazole,
isavuconazole)
Itraconazole, ketoconazole, and
voriconazole concentrations may
be subtherapeutic with any of the
rifamycins. Fluconazole can be used
with rifamycins, but the dose of
fluconazole may have to be increased.
Atovaquone Consider alternate form of
Pneumocystis jirovecii treatment or
prophylaxis.
Chloramphenicol Consider an alternative antibiotic.
Mefloquine Consider alternate form of malaria
prophylaxis.
Hormone therapy Ethinylestradiol,
norethindrone
Women of reproductive potential
on oral contraceptives should be
advised to add a barrier method of
contraception when on a rifamycin.
Tamoxifen May require alternate therapy or use of
a non-rifamycin-containing regimen.
Levothyroxine Monitoring of serum TSH
recommended; may require increased
dose of levothyroxine.
Narcotics Methadone RIF and RPT use may require
methadone dose increase. RFB
infrequently causes methadone
withdrawal.
Anticoagulants Warfarin Monitor prothrombin time; may
require 2- to 3-fold warfarin dose
increase.
Table 8. Clinically Significant Drug–Drug Interactions
Involving the Rifamycins
a
(cont'd)
