An Interaction Study to Assess Drug Levels in Fasting Healthy Adult Subjects

This randomized, open-label, six-arm, three-period drug interaction study will recruit 48 healthy volunteers so as to obtain a minimum of 36 evaluable subjects at a single study center in the U.S. The study will have a screening visit, 3 treatment visits for pharmacokinetics (PK) sampling and a follow-up visit. The screening visit will be conducted within 30 days prior to receiving the first dose. Subjects will then be randomized into 1 of 6 treatment groups as shown below:

Cohort Size Period 1 Period 2 Period 3 Sample Days 1 to 7 Days 1-14 Days 1-14

A 8 RTG 400mg BID, FPV 1400mg BID, FPV 1400mg BID + RTG 400mg BID

B 8 RTG 400mg BID, FPV 1400mg BID + RTG 400mg BID , FPV 1400mg BID

C 8 RTG 400mg BID, FPV 700mg BID + RTV 100mg BID, FPV 700mg BID + RTV 100mg BID + RTG 400mg BID

D 8 RTG 400mg BID, FPV 700mg BID + RTV 100mg BID + RTG 400mg BID, FPV 700mg BID + RTV 100mg BID

E 8 RTG 400mg BID, FPV 1400mg QD + RTV 100mg QD, FPV 1400mg QD + RTV 100mg QD + RTG 400mg BID

F 8 RTG 400mg BID, FPV 1400mg QD + RTV 100mg QD + RTG 400mg BID, FPV 1400mg QD + RTV 100mg QD

Study subjects will enter the clinic in the morning prior to dosing in a fasting state and remain at the center for 12 hours following each dose. Fourteen to 21 days following completion of the third dosing period, study subjects will return to the clinic for follow-up assessment. The total duration of the study will be approximately 86 days from screening through follow up. Blood samples for drug concentration measurement of amprenavir (APV) and raltegravir (RTG) concentrations will be collected over 12 hours at the end of each dosing period (at 0 [baseline], 0.5, 1, 1.5, 2, 3, 4, 6, 8, and 12 hours post-dose). Subjects will undergo a physical examination, CBC with differential, HIV test, hepatitis B/C test, liver function test, renal function analysis, and lipid panel at screening, and all of these tests except those for HIV and hepatitis B/C will be repeated at follow-up post-study. Adverse events and adherence (by pill count and medication diary) will be assessed by the investigator/study personnel at the end of each dosing period. Evaluable patients will be required to have adhered to at least 95% of their study drug doses. Plasma APV concentrations will be analyzed using a validated high-performance liquid chromatography method with tandem mass spectrometric detection (HPLC/MS/MS) and plasma RTG concentrations by triple quadruple mass spectrometry. Plasma APV and RTG pharmacokinetic parameters measured will include maximum concentration (Cmax), time to maximum concentration (Tmax), minimum concentration (Cmin), and area under the concentration-time curve (AUC). All these parameters, except Tmax, will be log-transformed before statistical analysis. Analysis of variance, considering treatment as a fixed effect and subject as a random effect will be performed using Statistical Analysis Software (SAS), and assuming a treatment ratio for steady-state APV PK parameters as 1.0, the 90% confidence intervals will be within the range 0.81-1.24