Treatment simplification to once daily darunavir/ritonavir guided by the darunavir inhibitory quotient in heavily pretreated HIV-infected patients.

Background: We explored a treatment simplification strategy to darunavir/ritonavir 900/100 mg once daily guided by the darunavir virtual inhibitory quotient (vIQ) in patients receiving salvage therapy with darunavir/ritonavir 600/100 mg twice daily.

Methods: Open-label, randomized pilot study in HIV-infected patients on darunavir/ritonavir 600/100 mg twice daily (viral load 50 copies/ml; darunavir vIQ >2). Thirty patients were randomized to darunavir/ritonavir 900/100 mg once daily (once-daily group, n=15) or 600/100 mg twice daily (twice-daily group, n=15). Viral load, blood chemistry, and darunavir and ritonavir trough plasma concentrations (C(trough)) were determined up to 48 weeks. If the darunavir vIQ fell to 1.5, the dosage was switched to 600/100 mg twice daily. The primary end point was the percentage of 48-week treatment failure.

Results: Patients had taken a mean 11.6 (sd +/-3.9) antiretroviral regimens before darunavir/ritonavir administration. The proportion of patients without 48-week treatment failure was 86.7% in both groups. The median (interquartile range [IQR]) darunavir C(trough) decreased from 3.09 mg/l (IQR 2.43-3.93) at baseline to 1.60 mg/l (IQR 1.25-2.04) at week 48 (P=0.001) in the once-daily group. Three once-daily group patients switched to darunavir/ritonavir 600/100 mg twice daily. Fewer patients had triglyceride levels >200 mg/dl at week 48 in the once-daily group (20.0%) than in the twice-daily group (20.0% versus 57.1%; P=0.046).

Conclusion: Patients had taken a mean 11.6 (sd +/-3.9) antiretroviral regimens before darunavir/ritonavir administration. The proportion of patients without 48-week treatment failure was 86.7% in both groups. The median (interquartile range [IQR]) darunavir C(trough) decreased from 3.09 mg/l (IQR 2.43-3.93) at baseline to 1.60 mg/l (IQR 1.25-2.04) at week 48 (P=0.001) in the once-daily group. Three once-daily group patients switched to darunavir/ritonavir 600/100 mg twice daily. Fewer patients had triglyceride levels >200 mg/dl at week 48 in the once-daily group (20.0%) than in the twice-daily group (20.0% versus 57.1%; P=0.046).