Coadministration has not been studied. No dose adjustment is necessary when Triumeq is combined with nucleoside reverse transcriptase inhibitors.

Fifteen HIV-1–infected subjects were enrolled in a crossover-designed drug interaction trial evaluating single doses of abacavir (600 mg), lamivudine (150 mg), and zidovudine (300 mg) alone or in combination. Analysis showed no clinically relevant changes in the pharmacokinetics of abacavir with the addition of lamivudine or zidovudine or the combination of lamivudine and zidovudine. Lamivudine exposure (AUC decreased 15%) and zidovudine exposure (AUC increased 10%) did not show clinically relevant changes with concurrent abacavir. No clinically significant alterations in lamivudine or zidovudine pharmacokinetics were observed in 12 asymptomatic HIV-1-infected adult patients given a single dose of zidovudine (200 mg) in combination with multiple doses of lamivudine (300 mg every 12 hours).

Multiple dose pharmacokinetics were determined in HIV-infected subjects following coadministration of abacavir (200, 400 or 600 mg three times daily or 300 mg twice daily) alone or with zidovudine (200 mg three times daily or 300 mg twice daily). Coadministration of zidovudine had only small and inconsistent effects on the steady state pharmacokinetics of abacavir that did not increase with dose. At the clinical abacavir dose (300 mg twice daily), zidovudine coadministration had no effect on abacavir AUC. The pharmacokinetic profiles of zidovudine in the absence of abacavir were not determined; however, mean AUC and Cmax values for zidovudine in the presence of abacavir were comparable to historical steady state values. 

The pharmacokinetics and safety of single doses of abacavir (600 mg), zidovudine (300 mg) and lamivudine (150 mg) were evaluated when given alone or with either or both of the other drugs to 13 HIV-infected subjects. Coadministration of abacavir with zidovudine (with or without lamivudine) decreased ZDV Cmax by ~20%, delayed ZDV Tmax by 0.5h and increased AUC of zidovudine glucuronide by up to 40%. There were no differences in the pharmacokinetics of abacavir when given alone, or with zidovudine or lamivudine, or with both zidovudine and lamivudine.