Peripheral Pharmacodynamics of Phentermine_Topiramate in Obese Patients

Investigators propose a randomized controlled trial of combination phentermine topiramate
versus placebo given orally for 10-15 days. Dosing of 3.75/23 mg days 1-5, increased to
7.5/46 mg days 6-14. Participants will be randomized according to a computer generated
randomization schedule generated by the study statistician's office and submitted to the
Mayo Clinic CTSA research pharmacy. Allocation will be concealed. The study blind will be
retained until all the data on gastric emptying, accommodation, satiation and satiety have
been recorded and transmitted to the statistician for data lock.

INCLUSION CRITERIA

- Obese subjects with BMI> 30 Kg/m2: Otherwise healthy individuals who are not
currently on treatment for cardiac, pulmonary, gastrointestinal, hepatic, renal,
hematological, neurological, endocrine (other than hyperglycemia not requiring
medical therapy) and unstable psychiatric disease.

- Age: 18-70 years

- Gender: Men or women. Women of childbearing potential will have negative pregnancy
test before initiation of medication.

EXCLUSION CRITERIA

- Weight >300 lbs which is the limit of safety for the SPECT scanner

- Concomitant use of appetite suppressants (i.e. caffeine based or diethylpropion) or
orlistat (Xenical®)

- Uncontrolled hypertension (Blood pressure greater than 160/90 mmHg)

- Concentration of fasting glucose greater than 240 mg/dl

- Concentration of triglycerides greater than 400 mg/dl

- Type 1 Diabetes

- use of anti-diabetic drugs other than metformin,

- history of nephrolithiasis,

- recurrent major depression, presence or history of suicidal behaviour or ideation
with intent to act, and current substantial depressive symptoms (Patient Health
Questionnaire [PHQ-9]21 total score ≥10).

- Concomitant use of MAOI inhibitors (i.e. phenelzine, selegiline), serotonergic
agents, and other centrally acting appetite suppressants

- Significant psychiatric dysfunction based upon screening with the Hospital Anxiety
and Depression Scale [HADS] self-administered alcoholism screening test (SAAST,
substance abuse) and the questionnaire on eating and weight patterns (binge eating
disorders and bulimia). If such a dysfunction is identified by a HADS score ≥11 in
any of the subscales or difficulties with substance or eating disorders, the
participant will be excluded and given a referral letter to his/her primary care
doctor for further appraisal and follow-up.

- End stage renal disease or liver cirrhosis

- Intake of medication that could interfere with the interpretation of the study or
cause drug interaction (i.e. ketoconazole, erythromycin). Specifically, birth
control pill, estrogen replacement therapy, and thyroxine replacement are
permissible.