The goal of this clinical research study is to learn how zileuton alone or the combination of zileuton and celecoxib may affect certain chemicals in the body that may be linked with a risk for smoking-related lung disease. These effects will be measured by a urine test

PRIMARY OBJECTIVES:

I. To determine whether short-term administration of zileuton, a 5-lipoxygenase (5-LO) inhibitor, in current smokers will suppress the formation of urinary leukotriene E4 (LTE4) and shunt arachidonic acid into the cyclooxygenase (COX) pathway, resulting in elevated urinary prostaglandin E-metabolite (PGE-M).

SECONDARY OBJECTIVES:

I. To determine whether short-term co-administration of celecoxib, a selective COX-2 inhibitor, and zileuton suppresses levels of both urinary LTE4 and PGE-M in current smokers.

II. To evaluate the association between baseline levels of urinary LTE4 and magnitude of the arachidonic acid shunt induced by zileuton.

OUTLINE: Patients are randomized to 1 of 2 treatment arms.

ARM I: Patients receive zileuton orally (PO) twice daily (BID) on days 1-6.

ARM II: Patients receive zileuton as in Arm I and celecoxib PO BID on days 1-6.

Inclusion Criteria:

• Male or female current tobacco smokers with more or equal to 10 pack years of self-reported smoking exposure and an average of more or equal to 10 cigarettes/day
• Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 (Karnofsky 70-100%)
• Total bilirubin less or equal to 2 * upper limit of normal (ULN)
• Direct bilirubin less or equal to 2 * ULN
• aspartate aminotransferase (AST)/(SGOT) less or equal to 2 * ULN
• alanine aminotransferase (ALT)/(SGPT) less or equal to 2 * ULN
• Alkaline phosphatase less or equal to 2 * ULN
• If the participant is female, of childbearing potential and not lactating, she has a documented negative serum pregnancy test within 14 days prior to randomization

Exclusion Criteria:

• The participant has active cancer (excluding non-melanoma skin cancer)
• The participant has a history of curatively treated cancer with surgical therapy finished within 6 months prior to the Screening visit; or has had chemotherapy, cancer-related immunotherapy, hormonal therapy (other than Hormone replacement therapy (HRT) for menopause), or radiation therapy within 12 months of the screening visit
• The participant has a chronic inflammatory condition, including but not limited to, ulcerative colitis, Crohn's disease, rheumatoid arthritis, psoriasis, gout and pancreatitis
• The participant has an ongoing or active infection, including but not limited to HIV, pneumonia, urinary tract infection
• The participant has a history of nonsteroidal anti-inflammatory drugs (NSAIDs) use, including aspirin (low-dose aspirin also prohibited) and selective COX-2 inhibitors within the previous 4 weeks
• The participant has used zileuton or a leukotriene receptor antagonist within the previous 4 weeks
• The participant has a history of corticosteroid use (excluding topical nasal sprays and dermal application) within the last 6 weeks
• The participant has an acute or chronic kidney disorder
• The participant exhibits clinical evidence of active liver disease or history of chronic liver disease
• The participant has active cardiac disease, or a history of myocardial infarction, angina or coronary artery disease within the past 6 months
• The participant has a history of a cerebrovascular accident (CVA) or transient ischemic attack (TIA)
• The participant has a bleeding history
• The participant is taking drugs known to interact with zileuton or celecoxib, including theophylline, warfarin, propranolol, fluconazole or lithium
• The participant has received any investigational medication within 30 days of the screening visit or is scheduled to receive an investigational agent during the study
• The participant is pregnant or nursing; women must not be pregnant or lactating
• The participant is a female of child-bearing potential (women are considered not of childbearing potential if they are at least two years postmenopausal and/or surgically sterile) who has not used adequate contraception (abstinence; barrier methods such as intrauterine device (IUD), diaphragm with spermicidal gel, condom, or others; and hormonal methods such as birth control pills or others) since her last menses prior to study entry
• The participant is a female of child-bearing potential or male who does not agree to use adequate contraception for the duration of study participation; should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her study physician immediately
• The participant has participated in the study previously and was withdrawn
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements
• Pregnant or nursing participants or those who are HIV-positive will be excluded from the study

Of the 80 participants treated three (3) were lost to follow up leaving 77 who completed treatment, and of those reflected as a subset are the 70 compliant participants who completed treatment.

All adverse events that occur after the informed consent signed (including run-in) until subject off study. Study period was from May 2010 to September 2011.

Common Toxicity reporting for the study began with Common Toxicity Criteria for Adverse Effects (CTCAE) version 3.0 and completed with CTCAE version 4.0. Reporting has been combined in the provided tables.