This is a two part protocol (Parts A and B) in healthy volunteers evaluating the pharmacokinetics/ pharmacodynamics (PK/PD) of azithromycin to investigate the usefulness of various biomarkers (e.g., Interleukin-10 (IL-10), Granulocyte macrophage colony-stimulating factor (GM-CSF), mature dendritic cell (MDC), with and without ex vivo lipopolysaccharide (LPS) stimulation) as markers of macrolide anti-inflammatory activity.

Part A is a randomized, open-label parallel group study evaluating PK/PD of a single azithromycin dose of 250 or 1000 mg. Data from Part A will be used to assess the dose resulting in induction/inhibition of various ex vivo biomarkers relative to a 250 mg dose of azithromycin (the clinical dose used in treatment of neutrophil-induced inflammatory conditions). This information will guide the range of doses to be studied in a first time in humans (FTIH) study of a new chemical entity.

Part B is a repeat dose study treating subjects with Azithromycin (250 mg every other day for 3 weeks), the dose approximates that used in the treatment of chronic neutrophil related inflammatory conditions. This information will provide insight into whether the biomarker effects change over time on repeat dosing and any potential differences observed between single and repeat doses.

This is a two part protocol (Parts A and B) in healthy volunteers evaluating the pharmacokinetics/ pharmacodynamics (PK/PD) of azithromycin to investigate the usefulness of various biomarkers (e.g., IL-10, GM-CSF, MDC, with and without ex vivo lipopolysaccharide (LPS) stimulation) as markers of macrolide anti-inflammatory activity.

Part A is a randomized, open-label parallel group study evaluating PK/PD of a single azithromycin dose of 250 or 1000 mg. Data from Part A will be used to assess the dose resulting in induction/inhibition of various ex vivo biomarkers relative to a 250 mg dose of azithromycin (the clinical dose used in treatment of neutrophil-induced inflammatory conditions). This information will guide the range of doses to be studied in a FTIH study of a new chemical entity.

Part B is a repeat dose study treating subjects with Azithromycin (250 mg every other day for 3 weeks), the dose approximates that used in the treatment of chronic neutrophil related inflammatory conditions. This information will provide insight into whether the biomarker effects change over time on repeat dosing and any potential differences observed between single and repeat doses.

Inclusion Criteria:

• Male or female between 18 and 65 years of age inclusive
• Non-childbearing potential defined as pre-menopausal females with a documented tubal ligation or hysterectomy
• Child-bearing potential and agrees to use one of the contraception methods
• Body weight ≥ 50 kg and body mass index (BMI) within the range 18.5 - 30 kg/m2 (inclusive)
• Capable of giving written informed consent, which includes compliance with the requirements and restrictions
• Single QT duration corrected for heart rate by Bazett's formula (QTcB) < 450 msec.

Exclusion Criteria:

• A positive pre-study Hepatitis B surface antigen or positive Hepatitis C antibody result within 3 months of screening
• Current or chronic history of liver disease, or known hepatic or biliary abnormalities
• A positive pre-study drug/alcohol screen
• A positive test for HIV antibody
• History of regular alcohol consumption within 6 months of the study
• The subject has participated in a clinical trial and has received an investigational product within the 3 months
• Exposure to more than four new chemical entities within 12 months prior to the first dosing day
• Use of prescription or non-prescription drugs, including vitamins, herbal and dietary supplements
• History of sensitivity to any of the study medications, or erythromycin, any macrolide or ketolide antibiotic
• Where participation in the study would result in donation of blood or blood products in excess of 500 mL within a 56 day period
• The subject has donated blood in the 3 months prior to the study
• Pregnant females as determined by positive serum or urine hCG test at screening or prior to dosing
• Lactating females
• Unwillingness or inability to follow the procedures outlined in the protocol
• Subject is mentally or legally incapacitated