Dosage Adjustments for ARV-ARV Drug Interactions

Many antiretroviral medications used to treat HIV infection, particularly certain protease inhibitors and nonnucleoside reverse transcriptase inhibitors, interact with other antiretroviral agents. These interactions are usually due to effects on hepatic drug metabolism and can cause clinically significant alterations in serum drug concentrations. Certain antiretroviral agents require dosage adjustment (or pharmacokinetic enhancement) when coadministered, and some combinations are contraindicated. This table shows evidence-based adult dosage adjustments for interacting antiretroviral medications. Not all are approved by the U.S. Food and Drug Administration.

For further information, see the Database of Antiretroviral Drug Interactions . For information about pharmacokinetic enhancement ("boosting") of protease inhibitors by ritonavir, see Dosing for Ritonavir-Boosted Protease Inhibitors .

Drug Coadministered Drug Dosage Adjustment Atazanavir Efavirenz Treatment-naive patients: Atazanavir 400 mg QD + ritonavir 100 mg QD; efavirenz 600 mg QD Treatment-experienced patients: Not recommended Etravirine Do not coadminister Nevirapine Do not coadminister Maraviroc Atazanavir 300 mg QD + ritonavir 100 mg QD; maraviroc 150 mg BID OR Atazanavir 400 mg QD; maraviroc 150 mg BID Saquinavir Dosage adjustment not established; consider atazanavir 300 mg QD + ritonavir 100 mg QD; saquinavir 1,600-2,000 mg QD Tenofovir Atazanavir 300 mg QD + ritonavir 100 mg QD; tenofovir 300 mg QD (atazanavir 400 mg QD + ritonavir 100 mg QD if used concurrently with tenofovir and an H2 receptor antagonist) Tipranavir Not recommended Darunavir Etravirine Darunavir 600 mg BID + ritonavir 100 mg BID; etravirine 200 mg BID (dosage adjustment not necessary) Maraviroc Darunavir 600 mg BID + ritonavir 100 mg BID; mariviroc 150 mg BID Delavirdine Indinavir Delavirdine 400 mg TID; indinavir 600 mg Q8H Saquinavir Delavirdine 400 mg TID; saquinavir 800 mg TID (monitor LFTs) Didanosine Tenofovir For body weight ≥60 kg, didanosine 250 mg QD; tenofovir 300 mg QD For body weight <60 kg, didanosine 200 mg QD; tenofovir 300 mg QD Efavirenz Atazanavir Treatment-naive patients: Atazanavir 400 mg QD + ritonavir 100 mg QD; efavirenz 600 mg QD Treatment-experienced patients: Do not coadminister. Fosamprenavir Efavirenz 600 mg QD; fosamprenavir 700 mg BID + ritonavir 100 mg BID OR Efavirenz 600 mg QD; fosamprenavir 1,400 mg QD + ritonavir 300 mg QD (QD dosing of fosamprenavir is not recommended for PI-experienced patients) Indinavir Efavirenz 600 mg QD; indinavir 800-1,000 mg BID + ritonavir 100-200 mg BID Lopinavir/ritonavir Efavirenz 600 mg QD; lopinavir/ritonavir 500/125 mg BID Maraviroc Efavirenz 600 mg QD; maraviroc 600 mg BID Saquinavir Dosage adjustment of saquinavir not established; consider efavirenz 600 mg QD; saquinavir 1,000 mg BID + ritonavir 200 mg BID Tipranavir Dosage adjustment not necessary Etravirine Atazanavir Do not coadminister Darunavir Etravirine 200 mg BID; darunavir 600 mg BID + ritonavir 100 mg BID (dosage adjustment not necessary) Lopinavir/ritonavir No dosage adjustment appears to be necessary Saquinavir Dosage adjustment not established; consider etravirine 200 mg BID; saquinavir 1000 mg BID + ritonavir 100 mg BID All other PIs Do not coadminister Maraviroc Etravirine 200 mg BID; maraviroc 600 mg BID (if ETV is given with MVC + DRV-r or other compatible RTV-boosted PI, reduce MVC dosage to 150 mg BID) Fosamprenavir Efavirenz Fosamprenavir 700 mg BID + ritonavir 100 mg BID; efavirenz 600 mg QD OR Fosamprenavir 1,400 mg QD + ritonavir 300 mg QD; efavirenz 600 mg QD (QD dosing of fosamprenavir is not recommended for PI-experienced patients) Etravirine Dosage adjustment not established; do not coadminister Lopinavir/ritonavir Fosamprenavir 1,400 mg BID; lopinavir/ritonavir 500/125 mg BID Maraviroc Fosamprenavir 1,400 mg BID; maraviroc 150 mg BID OR Fosamprenavir 700 mg BID + ritonavir 100 mg BID; maraviroc 150 mg BID OR Fosamprenavir 1,400 mg QD + ritonavir 200 mg QD; maraviroc 150 mg BID Nevirapine Dosage adjustment of fosamprenavir not established; consider fosamprenavir 700 mg BID + ritonavir 100 mg BID; nevirapine 200 mg BID OR Fosamprenavir 1,400 mg QD + ritonavir 300 mg QD; nevirapine 200 mg BID (QD dosing of fosamprenavir is not recommended for PI-experienced patients) Saquinavir Dosage adjustment not established; consider fosamprenavir 700 mg BID + ritonavir 100-200 mg BID; saquinavir 1,000 mg BID Tipranavir Not recommended Indinavir Delavirdine Indinavir 600 mg Q8H; delavirdine 400 mg TID Efavirenz Indinavir 800-1,000 mg BID + ritonavir 100-200 mg BID; efavirenz 600 mg QD Etravirine Do not coadminister Lopinavir/ritonavir Indinavir 600-800 mg BID; lopinavir/ritonavir 400/100 mg (2 tablets) BID Maraviroc Indinavir 800 mg BID + ritonavir 100 mg BID; maraviroc 150 mg BID OR Indinavir 800 mg Q8H; maraviroc 150 mg BID Nelfinavir Indinavir 1,200 mg BID; nelfinavir 1,250 mg BID Nevirapine Consider indinavir 800-1,000 mg BID + ritonavir 100-200 mg BID; nevirapine 200 mg BID Tipranavir Not recommended Lopinavir/ritonavir Efavirenz Lopinavir/ritonavir 500/125 mg BID (for ARV-naive patients) or 600/150 BID (Lopinavir/ritonavir should not be given QD in patients taking efavirenz.) Etravirine No dosage adjustment appears to be necessary Fosamprenavir Lopinavir/ritonavir 500/125 mg BID; fosamprenavir 1,400 mg BID Indinavir Lopinavir/ritonavir 400/100 mg (2 tablets) BID; indinavir 600-800 mg BID Maraviroc Lopinavir/ritonavir 400/100 mg (2 tablets) BID; maraviroc 150 mg BID Nevirapine Lopinavir/ritonavir 500/125 mg BID; nevirapine 200 mg BID (Lopinavir/ritonavir should not be given QD in patients taking nevirapine.) Saquinavir Lopinavir/ritonavir 400/100 mg (2 tablets) BID; saquinavir 1,000 mg BID Tipranavir Not recommended Maraviroc Amprenavir Atazanavir Darunavir Fosamprenavir Indinavir Lopinavir/ritonavir Saquinavir Maraviroc 150 mg BID; PI at usual dosage Efavirenz Etravirine (if used without PIs listed above or other strong CYP3A inhibitor) Maraviroc 600 mg BID, efavirenz 600 mg QD Maraviroc 600 mg BID, etravirine 200 mg BID Nevirapine Maraviroc 300 mg BID (dosage adjustment not necessary); nevirapine 200 mg BID Tipranavir Maraviroc 300 mg BID (dosage adjustment not necessary); tipranavir 500 mg BID + ritonavir 200 mg BID Nelfinavir Indinavir Nelfinavir 1,250 mg BID; indinavir 1,200 mg BID Etravirine Do not coadminister Maraviroc Nelfinavir 1,250 mg BID; maraviroc 150 mg BID Nevirapine Atazanavir Do not coadminister Fosamprenavir Dosage adjustment of fosamprenavir not established; consider nevirapine 200 mg BID; fosamprenavir 700 mg BID + ritonavir 100 mg BID OR Nevirapine 200 mg BID; fosamprenavir 1,400 mg QD + ritonavir 300 mg QD (QD dosing of fosamprenavir is not recommended for PI-experienced patients) Indinavir Consider nevirapine 200 mg BID; indinavir 800-1,000 mg BID + ritonavir 100-200 mg BID Lopinavir/ritonavir Nevirapine 200 mg BID; lopinavir/ritonavir 500/125 mg BID Maraviroc Nevirapine 200 mg BID; maraviroc 300 mg BID (dosage adjustment not necessary) Saquinavir Dosage adjustment of saquinavir not established; consider nevirapine 200 mg BID; saquinavir 400 mg BID + ritonavir 400 mg BID Tipranavir Dosage adjustment not established Saquinavir Atazanavir Dosage adjustment not established; consider saquinavir 1,600-2,000 mg QD + atazanavir 300 mg QD + ritonavir 100 mg QD Delavirdine Saquinavir 800 mg TID; delavirdine 400 mg TID (monitor LFTs) Efavirenz Dosage adjustment of saquinavir not established; consider saquinavir 1,000 mg BID + ritonavir 200 mg BID; efavirenz 600 mg QD Etravirine Saquinavir 1000 mg BID + ritonavir 100 mg BID; etravirine 200 mg BID Fosamprenavir Dosage adjustment not established; consider saquinavir 1,000 mg BID + ritonavir 100-200 mg BID; fosamprenavir 700 mg BID Lopinavir/ritonavir Saquinavir 1,000 mg BID; lopinavir/ritonavir 400/100 mg (2 tablets) BID Maraviroc Saquinavir 1,000 mg BID + ritonavir 100-200 mg BID; maraviroc 150 mg BID Nevirapine Dosage adjustment of saquinavir not established; consider saquinavir 400 mg BID + ritonavir 400 mg BID; nevirapine 200 mg BID Tipranavir Not recommended Tenofovir Atazanavir Tenofovir 300 mg QD; atazanavir 300 mg QD + ritonavir 100 mg QD (atazanavir 400 mg QD + ritonavir 100 mg QD if used concurrently with tenofovir and an H2 receptor antagonist) Didanosine Tenofovir 300 mg QD; didanosine 250 mg QD (for body weight ≥60 kg) Tenofovir 300 mg QD; didanosine 200 mg QD (for body weight <60 kg) Tipranavir Atazanavir Darunavir Fosamprenavir Lopinavir/ritonavir Saquinavir Combination of tipranavir and other PIs is not currently recommended Efavirenz Nevirapine Dosage adjustment not necessary Etravirine Do not coadminister Maraviroc Tipranavir 500 mg BID + ritonavir 200 mg BID; maraviroc 300 mg BID (dosage adjustment not necessary)

Abbreviations : ARV = antiretroviral; BID = 2 times daily; LFTs = liver function tests; PI = protease inhibitor; Q8H = every 8 hours; QD = once daily; TID = 3 times daily

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