Part A: Drug Interaction Study of Sofosbuvir and Antiretroviral Therapy (ART) Combinations in HIV and Hepatitis C Virus (HCV) Co-infected Patients. Part B: Efficacy and Safety of Sofosbuvir for 12 Weeks in HIV/HCV Co-infected Patients.

Part A: Plasma Pharmacokinetics of SOF, EFV, Tenofovir (TFV), and FTC: AUCtau at Day 7

AUCtau: concentration of drug over time (area under the plasma concentration versus time curve over the dosing interval). Data for this outcome measure were collected for participants in Part A only.

Time frame: Pre-dose and 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, 12 hours postdose

Part A: Plasma Pharmacokinetics of SOF, EFV, TFV, and FTC: Cmax at Day 7

Cmax: maximum observed concentration of drug in plasma. Data for this outcome measure were collected for participants in Part A only.

Time frame: Pre-dose and 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, 12 hours postdose

Part B: Percentage of Participants With Sustained Virologic Response (SVR) at 12 Weeks After Discontinuation of Therapy (SVR12)

SVR12 was defined as HCV RNA \< the lower limit of quantitation (LLOQ; ie, 25 IU/mL) at 12 weeks after stopping study treatment. Data for this outcome measure were collected for participants in Part B only.

Time frame: Posttreatment Week 12

Incidence of Adverse Events Leading to Permanent Discontinuation of Study Drug(s)

The percentage of participants discontinuing any study drug due to an adverse event was summarized.

Time frame: Up to 12 weeks