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Home > Treatment > HIV Meds Quarterly > Summer 2011 > ARV Interactions
Updates to the Database of ARV Drug Interactions
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The following table summarizes recent additions to the HIV InSite Database of Antiretroviral Drug Interactions. For a full description of the updates, including references to the studies from which the data were derived, go to the database, click on a specific drug name, and search for the interacting agent.

New ARV Interactions (April 2011-August 2011)
Drug OneDrug TwoClinical EffectsMechanismsManagement
Source: McNicholl I. HIV InSite Database of Antiretroviral Drug Interactions. University of California San Francisco: Center for HIV Information; 2011
AtazanavirColchicineIncreased colchicine effectsInhibition of CYP450 3A4 by atazanavir/ritonavirFor treatment of gout, reduce colchicine dosage to 0.6 mg x 1 then 0.3 mg 1 hour later; do not repeat dosing earlier than 3 days thereafter

For prophylaxis of gout, reduce colchicine dosage to 0.3 mg QD if on 0.6 mg BID prior to PI therapy, or reduce colchicine dosage to 0.3 mg QOD if on 0.6 mg QD prior to PI therapy
AtazanavirTelaprevirNo dosage adjustment necessary
DarunavirColchicineIncreased colchicine effectsInhibition of CYP450 3A4 by darunavir/ritonavirFor treatment of gout, reduce colchicine dosage to 0.6 mg x 1 then 0.3 mg 1 hour later; do not repeat dosing earlier than 3 days thereafter

For prophylaxis of gout, reduce colchicine dosage to 0.3 mg QD if on 0.6 mg BID prior to PI therapy, or reduce colchicine dosage to 0.3 mg QOD if on 0.6 mg QD prior to PI therapy
DarunavirMaravirocInhibition of CYP450 3A4 by darunavir/ritonavirNo dosage adjustment necessary
DarunavirRilpivirineIncreased rilpivirine effectsNo dosage adjustment necessary
Darunavir
600 mg BID with ritonavir 100 mg BID x 20 days
Telaprevir
750 mg Q8H x 10 days
Decreased telaprevir effects; decreased darunavir effectsDo not coadminister

Alternative agents:

Atazanavir/ritonavir
Darunavir
600 mg BID with ritonavir 100 mg BID x 24 days
Telaprevir
1,125 mg Q12H x 4 days
Possible telaprevir effects; decreased darunavir effectsDo not coadminister

Alternative agents:
Atazanavir/ritonavir
DidanosineRilpivirineNo dosage adjustment necessary; administer didanosine on an empty stomach and at least 2 hours before or at least 4 hours after rilpivirine (which must be administered with a meal)
Efavirenz
600 mg QD x 16 days
Boceprevir
800 mg TID x 6 days
Possible decreased boceprevir effectsDo not coadminister

Alternative agents:

Telaprevir
EfavirenzCisaprideIncreased cisapride effects (eg, cardiac arrhythmias)Do not coadminister

Alternative agents:

Metoclopramide
EfavirenzClarithromycinInduction of CYP450 3A4 by efavirenzDosage adjustment not established
Efavirenz
600 mg QD x 7 days, administered with tenofovir 300 mg QD x 7 days
Telaprevir
1,125 mg Q8H x 7 days
No dosage adjustment necessary
Efavirenz
600 mg QD x 20 days
Telaprevir
750 mg Q8H x 10 days
Decreased telaprevir effectsInduction of CYP450 3A4 by efavirenzIncrease telaprevir dosage to 1,125 mg Q8H
FosamprenavirColchicineIncreased colchicine effectsInhibition of CYP450 3A4 by fosamprenavir/ritonavirFor treatment of gout, reduce colchicine dosage to 0.6 mg x 1 then 0.3 mg 1 hour later; do not repeat dosing earlier than 3 days thereafter

For prophylaxis of gout, reduce colchicine dosage to 0.3 mg QD if on 0.6 mg BID prior to PI therapy, or reduce colchicine dosage to 0.3 mg QOD if on 0.6 mg QD prior to PI therapy
Fosamprenavir
700 mg with ritonavir
100 mg BID x 20 days
Telaprevir
750 mg Q8H x 10 days
Decreased telaprevir effects; decreased amprenavir effectsDo not coadminister

Alternative agents:
Atazanavir/ritonavir
Fosamprenavir
700 mg with ritonavir
100 mg BID x 24 days
Telaprevir
1,125 mg Q12H x 4 days
Do not coadminister

Alternative agents:
Atazanavir/ritonavir
IndinavirColchicineIncreased colchicine effectsInhibition of CYP450 3A4 by indinavirFor treatment of gout, reduce colchicine dosage to 0.6 mg x 1 then 0.3 mg 1 hour later; do not repeat dosing earlier than 3 days thereafter

For prophylaxis of gout, reduce colchicine dosage to 0.3 mg QD if on 0.6 mg BID prior to PI therapy, or reduce colchicine dosage to 0.3 mg QOD if on 0.6 mg QD prior to PI therapy
Lopinavir/ritonavirColchicineIncreased colchicine effectsInhibition of CYP450 3A4 by lopinavir/ritonavirFor treatment of gout, reduce colchicine dosage to 0.6 mg x 1 then 0.3 mg 1 hour later; do not repeat dosing earlier than 3 days thereafter

For prophylaxis of gout, reduce colchicine dosage to 0.3 mg QD if on 0.6 mg BID prior to PI therapy, or reduce colchicine dosage to 0.3 mg QOD if on 0.6 mg QD prior to PI therapy
Lopinavir/ritonavirRilpivirineIncreased rilpivirine effectsNo dosage adjustment necessary
Lopinavir/ritonavirTelaprevirDecreased telaprevir effectsDo not coadminister

Alternative agents:
Atazanavir/ritonavir
NelfinavirColchicineIncreased colchicine effectsInhibition of CYP450 3A4 by nelfinavirFor treatment of gout, reduce colchicine dosage to 0.6 mg x 1 then 0.3 mg 1 hour later; do not repeat dosing earlier than 3 days thereafter

For prophylaxis of gout, reduce colchicine dosage to 0.3 mg QD if on 0.6 mg BID prior to PI therapy, or reduce colchicine dosage to 0.3 mg QOD if on 0.6 mg QD prior to PI therapy
RilpivirineAcetaminophenNo dosage adjustment necessary
RilpivirineAntacidsPossible decreased rilpivirine effectsDecreased gastric acidity, leading to impaired drug solubility and absorptionAdminister antacids at least 2 hours before or at least 4 hours after rilpivirine
RilpivirineAtorvastatinNo dosage adjustment necessary
RilpivirineChlorzoxazoneNo dosage adjustment necessary
RilpivirineEthinyl estradiol/norethindrone acetateNo dosage adjustment necessary
Rilpivirine
150 mg x 1
Famotidine
40 mg x 1 taken 2 hours before rilpivirine
Decreased rilpivirine effectsDecreased gastric acidity, leading to impaired drug solubility and absorptionAdminister H2 antagonist at least 12 hours before or at least 4 hours after rilpivirine
Rilpivirine
150 mg x 1
Famotidine
40 mg x 1 taken 4 hours after rilpivirine
No dosage adjustment necessary
Rilpivirine
150 mg x 1
Famotidine
40 mg x 1 taken 12 hours before rilpivirine
No dosage adjustment necessary
RilpivirineKetoconazoleDecreased ketoconazole effectsNo dosage adjustment necessary, but monitor for failure of antifungal therapy
RilpivirineMethadonePossible decreased methadone effects (eg, withdrawal)Monitor for signs and symptoms of methadone withdrawal; some patients may need an increase in the methadone dosage
RilpivirineOmeprazoleDecreased rilpivirine effectsDecreased gastric acidity, leading to impaired drug solubility and absorptionDo not coadminister

Alternative agents:

H2 antagonists, if administered at least 12 hours before or at least 4 hours after rilpivirine
RilpivirineRifabutinDecreased rilpivirine effectsDo not coadminister
RilpivirineRifampinDecreased rilpivirine effectsInduction of CYP450 3A4 by rifampinDo not coadminister
RilpivirineSildenafilNo dosage adjustment necessary
RilpivirineTenofovirPossible increased tenofovir effectsNo dosage adjustment necessary
RitonavirBoceprevirPossible decreased boceprevir effects; effect on ritonavir concentrations unknownClinical significance unknown, especially when combined with other PIs
RitonavirQuinineIncreased quinine effectsPossible competitive displacement from CYP450 3A4 and inhibition of 2D6Avoid combination if possible; if combination must be used a potential 4-fold reduction in quinine dosage may be needed
Ritonavir
100 mg x 1
Telaprevir
750 mg x 1
Dosage adjustment not established
Ritonavir
100 mg Q12H x 14 days
Telaprevir
750 mg Q12H x 14 days
Dosage adjustment not established
SaquinavirColchicineIncreased colchicine effectsInhibition of CYP450 3A4 by saquinavirFor treatment of gout, reduce colchicine dosage to 0.6 mg x 1 then 0.3 mg 1 hour later; do not repeat dosing earlier than 3 days thereafter

For prophylaxis of gout, reduce colchicine dosage to 0.3 mg QD if on 0.6 mg BID prior to PI therapy, or reduce colchicine dosage to 0.3 mg QOD if on 0.6 mg QD prior to PI therapy
Telaprevir
750 mg Q8H x 7 days
Tenofovir
300 mg QD x 7 days
Possible increased tenofovir effectsDosage adjustment not established
Telaprevir
1,125 mg Q8H x 7 days
Tenofovir
300 mg QD administered with efavirenz 600 mg QD x 7 days
Possible increased tenofovir effectsNo dosage adjustment necessary
Telaprevir
1,500 mg Q12H x 7 days
Tenofovir
300 mg QD administered with efavirenz 600 mg QD x 7 days
Possible decreased telaprevir effectsAdjust telaprevir dosage to 1,125 mg Q8H when used with efavirenz
TenofovirBoceprevirNo dosage adjustment necessary
TipranavirColchicineIncreased colchicine effectsInhibition of CYP450 3A4 by tipranavir/ritonavirFor treatment of gout, reduce colchicine dosage to 0.6 mg x 1 then 0.3 mg 1 hour later; do not repeat dosing earlier than 3 days thereafter

For prophylaxis of gout, reduce colchicine dosage to 0.3 mg QD if on 0.6 mg BID prior to PI therapy, or reduce colchicine dosage to 0.3 mg QOD if on 0.6 mg QD prior to PI therapy

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