Peripheral Pharmacodynamics of Phentermine-Topiramate in Obese Patients


About this study

Our overall goal is to determine the effect of Phentermine and Topiramate on gastric emptying, gastric accommodation, and satiety and satiation in obese participants.

Participation eligibility

Participant eligibility includes age, gender, type and stage of disease, and previous treatments or health concerns. Guidelines differ from study to study, and identify who can or cannot participate. There is no guarantee that every individual who qualifies and wants to participate in a trial will be enrolled. Contact the study team to discuss study eligibility and potential participation.


  • 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.


  • 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.

Participating Mayo Clinic locations

Study statuses change often. Please contact the study team for the most up-to-date information regarding possible participation.

Mayo Clinic Location Status

Rochester, Minn.

Mayo Clinic principal investigator

Michael Camilleri, M.D.

Closed for enrollment

More information


Publications are currently not available

Additional contact information

Non-cancer trials contact form

Phone: 800-664-4542 (toll-free)

International patient clinical studies questions