Initial analysis of results warranted a study re-design and work on the study was suspended.

This study is to compare intestinal Cytochrome P450 3A4 (CYP3A4) activity in 9-18 month post weight loss surgery Roux-en-Y Gastric Bypass (RYGB) versus control subjects who have not had a weight loss surgery and are of similar age, gender, body mass index as the gastric bypass group. For this purpose, we will compare post-bariatric surgery patients with control subjects on alterations in systemic exposure of buspirone, a CYP3A4 substrate, when administered with grapefruit juice, a selective intestinal CYP3A4 inhibitor.

Inclusion Criteria:

1. Male or Female
2. Age 18-65 (inclusive, at time of informed consent)
3. No tobacco use in the past three months.
4. Underwent Roux-en-Y Gastric Bypass weight loss surgery 9-18 months prior to study OR has not had a weight loss surgery but matches the gastric bypass patients on age, gender, and BMI.
5. Ability to read, write and understand English.
6. Expresses the ability/willingness to consume grapefruit juice.

Exclusion Criteria:

1. Taking a medication that has a clinically significant interaction with buspirone or grapefruit juice or an interaction that may alter the study data.
2. Hypersensitivity to buspirone or any excipient contained within the dosage forms or grapefruit juice.
3. Inability to tolerate repeated blood draws.
4. Any history of bipolar disorder or a psychotic disorder.
5. Current major depressive disorder or current suicidality.
6. Alcohol or substance dependence in the past year.
7. Currently pregnant or lactating or unwillingness to use medically accepted contraception during study.
8. Taking a medication which significantly alters gastrointesinal transit time.
9. Medical conditon which may increase participant risk with buspirone or grapefruit juice.
10. Self reported history of viral hepatits or HIV.
11. Positive urine drug screen unless documented prescription of a non-interacting medication.
12. Renal impairment as evidenced by an estimated glomerular filtration rate (eGFR) of less than or equal to 60 ml/min/1.73 m2 or other abnormality on a renal panel that the medical provider feels puts the participant at risk.
13. Hepatic insufficiency as defined by any hepatic enzyme greater than 3x the upper limit of normal or other hepatic laboratory abnormalities at the discretion of the medical provider.
14. Any contraindication to bioelectrical impedance analysis (BIA) such as pregnancy, the presence of a pacemaker or other implanted mechanical device.