Cardiovascular System in Obesity: Effect of Treatment

November 25, 2013 updated by: National Heart, Lung, and Blood Institute (NHLBI)
To determine the long-term efficacy of the combination therapy of phentermine and fenfluramine in conjunction with diet, exercise, and behavior modification in the treatment of simple, moderate obesity.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

BACKGROUND:

Obesity is a problem of significant public health concern both in this and other western countries. One reason is that it is a risk factor for cardiovascular disease, most notably hypertension. For example, in the Framingham study it was found that relative body weight, weight change during observation, and skin fold thickness were related to existing blood pressure levels and to the subsequent rate of development of hypertension. Additionally, for previously normotensive individuals, the risk of developing hypertension was proportional to the degree of overweight. Obesity is also a major risk factor for type II diabetes mellitus. On the other hand, some overweight individuals are physically healthy but suffer from the psychosocial consequences of their condition so that losing weight would be desirable for them as well as for individuals more at risk for physical illness.

Like essential hypertension, obesity is not only a chronic condition for many individuals but it is also a heterogeneous condition with many underlying causes and interacting factors. It is generally difficult to treat because it is a chronic problem, success comes slowly, and physicians in practice generally understand the condition rather poorly and do not manage it well. Results from studies of caloric restriction, behavior modification and medication have often been disappointing both to the subjects and their physicians. In practice, dropout rates from exercise programs, as well as various dietary self-help programs have been relatively high.

Similarly, in clinical trials dropout rates have often been quite high. Compounding the problem of weight management has been a rather universal negative bias on the part of physicians to prescribing anorexiant medications. It was previously generally held that these agents were either only effective in the short term or not at all. Additionally, there has always been concern about the potential adverse effects of anorexiants as well as their potential for abuse. Physicians who used appetite suppressants often prescribed them for only four to six weeks which was inappropriate in the management of a chronic condition.

In several relatively short term clinical trials (e.g., 16 weeks), it has been shown that appetite control medications such as fenfluramine and phentermine were more effective than placebo in inducing weight loss. It has been less clear from the trials performed heretofore how effective anorectic medications were when used as an adjunct to behavior modification and diet. This aspect was addressed in the first two years of the clinical trial under consideration here.

A second controversial issue concerned the duration of efficacy of anorexiant agents. Originally it was felt that tolerance developed, hence the recommendations for short courses of treatment. A few long-term double-blind studies using anorexiants have since demonstrated that they exert beneficial effects for up to 24 weeks, as evidenced by weight loss and maintenance of weight loss. This was an important finding given, as noted earlier, the chronicity of the problem of obesity.

The so-called stimulant anorexiants, like phentermine, are believed to act via central catecholamine mechanisms. Side-effects include nervousness, insomnia, increased motor activity and cardiovascular disturbances such as tachycardia and elevation of blood pressure. The latter effects led physicians to feel that their use in obese hypertensive patients was very limited. Fenfluramine, although chemically related to the stimulant anorexiants, appears to act via serotonergic mechanisms. It reportedly causes sedation, occasionally diarrhea and few cardiovascular effects.

DESIGN NARRATIVE:

Double-blind, fixed sample. After a six-week single-blind placebo controlled diet and behavior modification period, participants entered a parallel-group comparison of fenfluramine plus phentermine versus placebo. In the third and fourth years of the study, patients were randomly assigned to either continuous therapy or intermittent therapy. The intermittent therapy group received the medication for three months from April through June and during the period between Thanksgiving and New Year's day.

The study completion date listed in this record was obtained from the Query/View/Report (QVR) System.

Study Type

Interventional

Phase

  • Phase 2

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 60 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Men and women, ages 18 to 60. Body weight was 130 to 180 percent of ideal body weight.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

National Heart, Lung, and Blood Institute (NHLBI)

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

May 1, 1983

Study Completion (Actual)

April 1, 1988

Study Registration Dates

First Submitted

October 27, 1999

First Submitted That Met QC Criteria

October 27, 1999

First Posted (Estimate)

October 28, 1999

Study Record Updates

Last Update Posted (Estimate)

November 26, 2013

Last Update Submitted That Met QC Criteria

November 25, 2013

Last Verified

January 1, 2000

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 25
  • R01HL029188-04 (U.S. NIH Grant/Contract)

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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