This study is being conducted to evaluate how the body absorbs and processes the medication sertraline (Zoloft®) before compared to how it is absorbed at two time points after gastric bypass surgery. Participants will be asked to take part in this study at three time points: 1) before their bariatric surgery, 2) at three months following the surgery, and 3) twelve months following surgery. This study will enroll approximately 30 participants.

Inclusion Criteria:

• 1. Male or female between 18 and 60 years of age at the time of Informed Consent
• 2. Scheduled to undergo Roux en Y Gastric Bypass Surgery (RYGBP) or in evaluation for surgery prior to scheduling at the investigators' discretion.
• 3. Ability to swallow whole medication tablets and eat solid foods

Exclusion Criteria:

• 1. Those taking any medication at the time of the study which has a known, clinically significant, drug-interaction with sertraline, which may affect participant safety or threaten the validity of the data.
• 2. Hypersensitivity to sertraline or any excipient contained in either the tablet or solution
• 3. Inability to tolerate blood draws
• 4. History of or current bipolar disorder, psychotic disorder, or current major depressive disorder or suicidality, or other psychiatric condition that the investigator feels may put the subject at additional risk by participating in the study
• 5. Alcohol or other substance abuse in the past four weeks or dependence in the past year
• 6. Currently pregnant or lactating or any participant who wants to become pregnant during the study
• 7. Female participant unwilling to use an accepted method of birth control during the study assessment periods.
• 8. Disulfiram or metronidazole at baseline (due to small percentage of alcohol in sertraline solution) or other medication with a similar interaction with a very small amount of alcohol
• 9. Inability or unwillingness to avoid alcohol or grapefruit juice for the required study duration
• 10. Baseline medications which significantly alter gastrointestinal transit time (e.g. oral anticholinergic medications, metoclopramide, erythromycin) and are taken on a routinely scheduled basis. In addition, any such medication cannot be taken in close proximity (minimum of five half-lives of the drug) to the study sertraline administration.
• 11. Medical condition which may increase participant risk with sertraline
• 12. Hepatic insufficiency (Hepatic insufficiency will be defined as any liver enzyme test on a standard hepatic panel of greater than or equal to twice the upper limit of normal, or any other hepatic abnormality identified on physical exam, self-report, or laboratory testing that puts the participant at risk in the opinion of the study physician or physician assistant.)
• 13. History of daily tobacco product use in the past six months
• 14. Participants who have undergone any type of prior surgical procedure for weight loss
• 15. Significant Latex allergy (liquid form has a latex dropper)
• 16. Participant employed by, or who has immediate family employed by NRI
• 17. History of Hepatitis or HIV Infection