Effects of Treatment With Aprepitant (Emend®) in HIV Infected Individuals. 375 mg Dose

Inclusion Criteria: * HIV-1 infection, as documented by a rapid HIV test or any FDA-Approved HIV-1 Enzyme or Chemiluminescence Immunoassay (E/CIA) test kit and confirmed by Western blot at any time prior to study entry. * CD4+ cell count \>= 350/mm3 obtained within 90 days prior to study entry * Plasma HIV-1 RNA of \>=2,000 copies/mL as measured by any standard assay and performed within 90 days prior to study entry. * CCR5 tropic virus exclusively as determined by the Monogram tropism assay (PhenoSense Entry™) to be performed within 90 days of study entry. * Laboratory values obtained within 30 days prior to study entry, as follows: * Absolute neutrophil count (ANC) \>= 750/mm3 * Hemoglobin \>= 10.0 g/dL * Platelet count \>= 100,000/mm3 * Creatinine \<= 2 x ULN * AST (SGOT), ALT (SGPT), and alkaline phosphatase \<= 2 x ULN * Total bilirubin \<= 2.5 x ULN * Albumin \>= 3 g/dL * Female subjects of reproductive potential must have a negative spot urine pregnancy test result (with a sensitivity of at least 50 mIU/mL) performed at entry, prior to starting initial study treatment. * All subjects must agree not to participate in a conception process while on study drug and for 30 days after stopping the medication. * Karnofsky performance score \>= 80 within 30 days prior to study entry. * Men and women \> 18 years of age. * Ability and willingness of subject to give written informed consent. * Willing to return for a follow-up visit on day 42. * Subjects taking any precautionary concomitant medications must be on stable doses for \>8 weeks prior to study entry and have no plans to change medications or doses for the duration of the study. Exclusion Criteria: * Receipt of antiretroviral treatment within the 16 weeks prior to study entry or intent to initiate antiretroviral therapy within 60 days after entry. * Diabetes requiring treatment with oral hypoglycemics or insulin therapy. * Pregnancy within 90 days prior to study entry. * Breast-feeding. * Use of drugs that are inhibitors or inducers of metabolism by the cytochrome P450 CYP3A4 or CYP2C9 (such as warfarin and phenytoin) within 7 days of study entry. * Use of systemic corticosteroids or hormonal agents within 90 days prior to study entry. * Use of any immunomodulator, HIV vaccines, or investigational therapy within 90 days prior to study entry. * Any vaccination within 30 days prior to study entry. * Use of systemic cytotoxic chemotherapy within 90 days prior to study entry. * History of allergy to aprepitant or its formulations. * Active drug or alcohol use or dependence that, in the opinion of the investigator, would interfere with adherence to study requirements. * History of chronic active hepatitis B or C infection or severe hepatic dysfunction (Child-Pugh score \> 9) regardless of etiology * Serious illness requiring systemic treatment and/or hospitalization until subject either completes therapy or is clinically stable on therapy, in the opinion of the investigator, for at least 14 days prior to study entry. * Weight \< 40 kg or 88 lbs. within 90 days prior to study entry. * History of severe psychiatric comorbidities, such as depression, schizophrenia, mania, psychosis.