Please select the eligibility criteria that correspond to the clinical trial below.
Title: A Phase 4 Randomized, Double-Blind, Placebo-Controlled, Multicenter Study Evaluating The Efficacy And Safety Of Re-Treatment With Varenicline In Subjects Who Are Currently Smoking, And Who Have Previously Taken Varenicline
Brief Summary: The main purpose of this study is to compare the effectiveness and safety of the re-treatment of smokers with varenicline with placebo for smoking cessation during the last 4 weeks of a 12 week course of treatment. The study will also assess whether smokers remain abstinent at Week 24 (12 weeks after the end of treatment) and Week 52 (40 weeks after the end of treatment).


Options:
A: Inclusion Criteria:

* Is at least 18 years of age;
* Has smoked more than 10 cigarettes/day for ≥6 months;
* Is willing to make a quit attempt;
* Is able to participate fully in all aspects of the study;
* Has been provided with, understand, and have signed the informed consent.
* Is in good health as determined by the physician investigator.

Exclusion Criteria:

* Is clinically significant levels of current depression as assessed by CESD (Score \>16) and determined by the physician; or have a life-time diagnosis of bipolar disorder, schizophrenia or dementia as determined by physician investigator;
* Has an unstable medical condition.
* Is using other tobacco product and the primary use is NOT cigarettes.
* Is currently (within the past 30-days) using antipsychotics or antidepressants;
* Is currently (within the past 30-days) using any treatments for tobacco dependence (i.e., behavioral therapy, nicotine replacement therapy, bupropion SR, clonidine, or nortriptyline);
* Is currently using another investigational drug at the time of study enrollment;
* Is currently (within the past 30 days) using an herbal product or dietary supplement for tobacco abstinence;
* Has recent history (in the past 3-months) of alcohol abuse or dependence as assessed by the CAGE questionnaire and study investigators;
* Has a recent history of drug abuse as assessed by physician interview;
* Is pregnant, lactating, or of child bearing potential, likely to become pregnant during the medication phase and not willing to use a reliable form of contraception. Reliable forms of contraception include diaphragm or condom (with spermicidal), injections, intrauterine device \[IUD\], surgical sterilization and abstinence;
* Is a history of any major cardiovascular events in the past 3-months including unstable angina, acute MI or coronary angioplasty;
* Has clinically significant acute or chronic progressive or unstable neurologic, hepatic, renal, cardiovascular, respiratory or metabolic disease;
* Is currently on medications interacting with SAMe, including but not limited to, antidepressants, MAO inhibitors, levodopa, meperidine, dextromethorphan, pentazocine and tramadol;
* Has another household member or relative participating in the study;
* Has known allergy to SAMe.
B: Inclusion Criteria:

* Smokers aged 18 years or above and wanting to stop smoking
* Smokers who have smoked an average of at least 10 cigarettes per day over the last 4 weeks
* Smokers who have tried before to stop smoking at least once with varenicline, and who took varenicline for at least 2 weeks
* The last attempt to stop smoking must be at least 3 months before entering the study

Exclusion Criteria:

* Individuals who have not tolerated varenicline well previously, or who have a current or prior medical or psychiatric history that would make entry into the trial inadvisable
* Individuals who have previously participated in clinical trials of varenicline
* Individuals who have been participating in another smoking cessation trial within the last 3 months, or other drug trial within the last 30 days
C: Inclusion Criteria:

* Clinically stable patients with schizophrenia

Exclusion Criteria:

* Refractory schizophrenia
* Mental Retardation
* Serious Medical illness
D: Inclusion Criteria:

* The sample, 40 women and 40 men, will be hospitalized patients recruited from Stanford Hospital and Clinics who report smoking at least 10 cigarettes per day prior to hospitalization, have confirmed tobacco use by cotinine testing, and an expected hospitalization of at least 3 days duration from the date of study enrollment. Intention to quit smoking will not be required for study participation.

Exclusion Criteria:

- Study exclusion criteria are: dementia or other brain injury precluding ability to participate; Alzheimer's Disease; Parkinson's Disease; Huntington's Disease; meningitis; seizure disorder of a sustained nature; delirium; brain surgery; drug and/or alcohol dependence; suicidal ideation; end-stage renal disease (i.e., on dialysis); hypertensive crisis; stroke; myocardial infarction (MI) with severe cardiac damage; pregnancy or breastfeeding; non-English speaking; complete homelessness; or currently engaged in tobacco treatment. Study staff will consult with clinical staff prior to approach for study enrollment. In cases of severe renal impairment (estimated creatinine clearance \<30 mL/min), medical staff will consult with participants' physician to assess the appropriateness for study enrollment.

Answer: B