This is will be an open-label, fixed-sequence, multiple dose crossover study in 2 cohorts of 14 healthy male and/or female subjects, to estimate the effect of maraviroc on the pharmacokinetics of amprenavir and ritonavir and fosamprenavir/ritonavir on the pharmacokinetics of maraviroc.

Inclusion Criteria:

• Healthy male and/or female subjects between the ages of 18 and 55 years, inclusive.
• 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 14 drinks/week for females or 21 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.
• Positive result for HIV, Hepatitis B or Hepatitis C virus.
• 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.
• Known hypersensitivity or history of allergy to sulfonamides.