DXG; APD nucleoside derivative (oral, HIV-1) RFS Pharma; APD (oral, HIV-1, HBV); DXG prodrug (oral, HIV-1), RFS Pharma; APD (oral, HIV-1, HBV), RFS Pharma; Nucleoside reverse transcriptase inhibitor (oral, HIV-1, HBV), RFS Pharma; (-)-beta-D-2-aminopurine dioxolane; (-)-beta-D-dioxolane guanine