1. www.aids2014.org Tenofovir (TFV), Emtricitabine (FTC), Intracellular Metabolite (TFV-dp, FTC-tp), and Endogenous Nucleotide (dATP, dCTP) Concentrations as a Function of Aging in HIV+ Subjects Sparse-sampling PK study (4 samples) –Interim analysis; n = 43 (n = 28 EFV, n = 15 ATV/RTV) Hypothesis: chronologic age alone is not a predictor of PK changes in older HIV+ subjects –Fried frailty phenotyping, p16 INK4a expression analysis Calculated area-under-the-concentration-time- curve (AUC) for TFV, FTC, TFV-dp, FTC-tp, dATP, dCTP, EFV, ATV, RTV Tested for associations with subject characteristics, frailty, p16 INK4a expression –Report intracellular metabolite concentration: endogenous nucleotide ratios

2. www.aids2014.org Results- Statistical Analysis

3. www.aids2014.org Results- Endogenous Nucleotides TFV-dp: tenofovir diphosphate; dATP: deoxyadenosine triphosphate FTC-tp: emtricitabine triphosphate; dCTP: deoxycytidine triphosphate p<0.02 for association of dATP AUC and regimen