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:

* At least 18 years old
* Able to get to research lab in Burlington, Vermont or Omaha, Nebraska
* Daily smoker
* Smoke at least 8 cigarettes per day
* No reduction in smoking in last 30 days
* No intention to quit in the next 30 days
* Never used Varenicline before
* Not currently using smoking cessation medications or nicotine replacement therapy
* Willing to use Varenicline for at least 2 weeks
* Fluent in English

Exclusion Criteria:

* Cannot be currently pregnant or breastfeeding
* Kidney disease
* Frequent nausea
* On certain medications for asthma and/or depression
* Another household member in study
B: Inclusion Criteria:

* Male or female subjects, 18-75 years old
* Diagnosis of schizophrenia or schizoaffective disorder based on Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) criteria
* Smoking at least 10 cigarettes per day
* Weight of at least 100 lbs (45.4 kg)
* Motivation to quit smoking
* Stabilized psychotic symptoms
* Provision of informed consent for testing and treatment

Exclusion Criteria:

* Serious cardiac, renal, hypertensive, pulmonary, endocrine, or neurologic disorder
* Seizure disorder, recent withdrawal from alcohol or anxiolytics
* History of bulimia nervosa, anorexia nervosa, or dementia
* History of depression, panic, or bipolar disorders
* Pregnancy or lactation
* Prior use of varenicline or bupropion HCl within three months prior to initiation of the study
* Current use of other smoking cessation treatments
* Regular use of non-cigarette tobacco products (\> than once/week)
* Past substance abuse (alcohol or non-nicotine containing drugs) in the preceding 6 months
* Patients with suicidal ideations or plans
* Florid psychosis or increasing psychosis following varenicline or bupropion HCl treatment
* History of, or current, alcohol dependence/abuse
* Current use of monoamine oxidase inhibitors (MAOI)
C: 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
D: Inclusion Criteria:

* Males and females between 18 and 55 years old will be eligible for this study. Females must not be pregnant as determined by pregnancy screening, nor breast feeding, and must be using acceptable birth control methods during study participation.
* Current opioid dependence as evidenced by documentation of prior treatment for opioid dependence or signs of withdrawal, self-reported history of opioid dependence for consecutive 12 month period and a positive urine for opiates.
* Subjects must fulfill Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for opioid dependence.
* Subjects must have a history of cocaine use, with a reported street cocaine use of a minimum of 1/2 gram during the preceding 30 days.
* Subjects must meet DSM-IV criteria for cocaine dependence or abuse, and have laboratory confirmation of recent cocaine use (positive urine for cocaine) during the month prior to study entry.
* Subjects must be treatment-seekers for opioid and cocaine use.
* Subjects must have smoked at least 10 cigarette per day for at least one year. Varenicline's safety has only been studied in smokers.

Exclusion Criteria:

* History of heart disease, left ventricular hypertrophy, ischemic ECG changes, chest pain, arrhythmia, hypertension.
* History of severe renal or hepatic diseases.
* History of psychosis, schizophrenia, bipolar or major depressive disorder.
* History of seizure disorder.
* Current diagnosis of alcohol, benzodiazepine and other drug abuse or dependence (other than opiates, cocaine, and nicotine).
* Current use of over-the-counter or prescription psychoactive drugs (antidepressant, anxiolytics, antipsychotics, mood stabilizers, psychostimulants).
* Liver function tests (ALT or AST) greater than 3 times normal.
* Known allergy to varenicline or methadone.

Answer: C