This will be an open-label, fixed-sequence, multiple dose crossover study in 14 healthy male and/or female subjects, to estimate the effect of steady state lersivirine on the steady state pharmacokinetics of abacavir/lamivudine.

Inclusion Criteria:

• Healthy male and/or female subjects.
• Body Mass Index (BMI) of 17.5 to 30.5 kg/m2.
• Total body weight >50 kg (110 lbs).

Exclusion Criteria:

• History of regular alcohol consumption exceeding 7 drinks/week for females or 14 drinks/week for males (1 drink = 5 ounces (150 mL) of wine or 12 ounces (360 mL) of beer or 1.5 ounces (45 mL) of hard liquor) within 6 months of screening.
• Use of tobacco- or nicotine-containing products in excess of the equivalent of 5 cigarettes per day.
• Treatment with an investigational drug within 30 days (or as determined by the local requirement, whichever is longer) or 5 half-lives preceding the first dose of study medication.
• History of hypersensitivity to abacavir, lamivudine and/or lersivirine.