Appetite suppressant --Benzphetamine; Diethylpropion; Mazindol ; Phendimetrazine; Phentermine

Description

Sympathomimetic appetite suppressants are used in the short-term treatment of obesity. Their appetite-reducing effect tends to decrease after a few weeks. Because of this, these medicines are useful only during the first few weeks of a weight-loss program. The sympathomimetic appetite suppressants can help you to lose weight while you are learning new ways to eat and to exercise. Changes in eating habits and activity level must be developed and continued long-term in order for you to continue losing weight and to keep the lost weight from returning.

These medicines are available only with your doctor's prescription, in the following dosage forms:

Oral

·         Benzphetamine

o        Tablets (U.S.)

·         Diethylpropion

o        Tablets (U.S. and Canada)

o        Extended-release tablets (U.S. and Canada)

·         Mazindol

o        Tablets (U.S. and Canada)

·         Phendimetrazine

o        Extended-release capsules (U.S.)

o        Tablets (U.S.)

·         Phentermine

o        Capsules (U.S.)

o        Resin capsules (U.S. and Canada)

o        Tablets (U.S.)

Proper Use of This Medicine

In order to prevent trouble in sleeping, if you are taking:

·         One dose of this medicine a day, take it about 10 to 14 hours before bedtime.

·         More than one dose of this medicine a day, take the last dose of the day about 4 to 6 hours before bedtime.

For patients taking a long-acting form of this medicine:

·         Swallow these capsules or tablets whole. Do not break, crush, or chew before swallowing.

For patients taking mazindol:

·         This medicine may be taken with food, if needed, to prevent stomach upset.

Take this medicine only as directed by your doctor . Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. If too much is taken, it may cause unwanted effects or become habit-forming.

If you think this medicine is not working properly after you have taken it for a few weeks, do not increase the dose. Instead, check with your doctor.

Precautions While Using This Medicine

Your doctor should check your progress at regular visits to make sure that this medicine does not cause unwanted effects.

If you think this medicine is not working properly after you have taken it for a few weeks, do not increase the dose. Instead, check with your doctor.

Do not take an appetite suppressant with or less than 14 days after taking a monoamine oxidase (MAO) inhibitor. If you do, you may very suddenly develop extremely high blood pressure.

Taking a sympathomimetic appetite suppressant may cause a positive result in urine screening tests for amphetamines.

Sympathomimetic appetite suppressants may cause dryness of the mouth. For temporary relief, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if your mouth continues to feel dry for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of developing dental disease, including tooth decay, gum disease, and fungus infections.

This medicine may cause some people to feel a false sense of well-being or to become dizzy, lightheaded, drowsy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert.

Before having any kind of surgery, dental treatment, or emergency treatment, tell the medical doctor or dentist in charge that you are using this medicine. Taking appetite suppressants together with medicines that are used during surgery or dental or emergency treatments may cause serious side effects.

Check with your doctor immediately if you notice a decrease in your ability to exercise, if you faint, or if you have chest pain, swelling of your feet or lower legs, or trouble in breathing. These may be symptoms of very serious heart or lung problems.

If you have been taking this medicine for a long time or in large doses and you think you may have become mentally or physically dependent on it, check with your doctor.

·         Some signs of dependence on appetite suppressants are:

o        a strong desire or need to continue taking the medicine.

o        a need to increase the dose to receive the effects of the medicine.

o        withdrawal side effects (for example, mental depression, nausea or vomiting, stomach cramps or pain, trembling, unusual tiredness or weakness) when you stop taking the medicine.

For patients with diabetes:

·         This medicine may affect blood sugar levels. If you notice a change in the results of your urine or blood sugar test or if you have any questions, check with your doctor.

If you have been taking this medicine in large doses or for a long time, do not stop taking it without first checking with your doctor. Your doctor may want you to reduce gradually the amount you are taking before stopping completely. This will help prevent withdrawal side effects.

Side Effects of This Medicine

Side Effects of This Medicine

Appetite suppressants may cause some serious side effects, including heart and lung problems. You and your doctor should discuss the good this medicine may do as well as the risks of taking it.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

·         Rare

o        Chest pain;  decreased ability to exercise ;  fainting;  swelling of feet or lower legs;  trouble in breathing 

Check with your doctor as soon as possible if any of the following side effects occur:

·         More common

o        Increased blood pressure 

·         Less common or rare

o        Difficult or painful urination;  fast or irregular heartbeat;  feeling that others can hear your thoughts;  feeling that others are watching you or controlling your behavior;  hallucinations (feeling, seeing, or hearing things that are not there);  headache (severe);  mental depression;  numbness, especially on one side of the face or body;  skin rash or hives;  sore throat and fever (with diethylpropion) ;  talking, feeling, and acting with excitement and activity you cannot control;  unusual bleeding or bruising (with diethylpropion) 

·         Symptoms of overdose

o        Abdominal or stomach cramps;  coma;  confusion;  convulsions (seizures);  diarrhea (severe);  dizziness, lightheadedness, or fainting;  fast breathing;  feeling of panic;  fever;  hallucinations (seeing, hearing or feeling things that are not there);  high or low blood pressure;  hostility with urge to attack;  irregular heartbeat;  nausea or vomiting (severe);  overactive reflexes;  restlessness;  trembling or shaking;  tiredness, weakness, and mental depression following effects of excitement 

Abuse of a sympathomimetic appetite suppressant (taking the medicine in larger doses or taking it more frequently or for a longer time than the doctor ordered) can cause the following side effects:

·         Changes in personality;  excessive, excited activity;  irritability (severe);  mental illness (severe), similar to schizophrenia;  skin disease;  trouble in sleeping (severe) 

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

·         More common

o        Constipation;  dizziness or lightheadedness ;  dryness of mouth;  false sense of well-being;  headache;  irritability;  nausea or vomiting;  nervousness or restlessness;  stomach cramps or pain ;  trembling or shaking;  trouble in sleeping 

After the stimulant effects have worn off, drowsiness, unusual tiredness or weakness, or mental depression may occur.

·         Less common or rare

o        Blurred vision;  changes in sexual desire or decreased sexual ability;  diarrhea;  drowsiness;  frequent urge to urinate or increased urination;  increased sweating;  unpleasant taste 

Although not all of the side effects listed above have been reported for all of these medicines, they have been reported for at least one of them. However, since all of the sympathomimetic appetite suppressants are similar, any of the above side effects may occur with any of these medicines.

After you stop using this medicine, your body may need time to adjust. The length of time this takes depends on the amount of medicine you were using and how long you used it. During this time check with your doctor if you notice any of the following side effects:

·         Extreme tiredness or weakness;  mental depression;  nausea or vomiting;  stomach cramps or pain;  trembling;  trouble in sleeping or nightmares 

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Drug Targets Brain Circuits that Drive Appetite and Body Weight

Research conducted in animals has revealed that an appetite suppressant drug, D-fenfluramine (D-FEN), activates brain pathways that regulate food intake and body weight. The NIH-funded study suggests that drugs targeting central nervous system pathways affecting appetite, obesity, and anorexia may lead to selective, effective treatments for weight control. Results appear in the July 26, 2002, Science.

A study led by researchers at Beth Israel Deaconess Medical Center (BIDMC) found that anorexia induced by d-FEN in rodents activates melanocortin neurons in the central nervous system. The drug, once prescribed for losing weight and known as fen-phen when used with phentermine, was withdrawn by the Food and Drug Administration after reports of cardiac complications. The National Institute of Mental Health (NIMH) and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) supported the research.

The scientists set out to identify ways that d-FEN, which increases the brain's release of serotonin, a neurotransmitter that relays nerve impulses and curbs appetite, boosts this effect. Using a dose of d-FEN that reduced feeding behavior, they correlated anorexic effects with activity patterns in a network of neurons in the brain. Researchers targeted the arcuate nucleus (ARC) region of the hypothalamus, where pro-opiomelanocortin (POMC) neurons receive serotonin directly and signal to regions associated with regulating energy.

"Our study has linked the serotonin system, a classic brain pathway thought to be involved with eating disorders like anorexia nervosa, to the melanocortin system, a brain pathway involved in obesity," explained the study's senior author, Joel Elmquist, D.V.M., Ph.D., a neuroscientist and endocrinologist at BIDMC and Associate Professor of Endocrinology and Medicine at Harvard Medical School.

Using electrophysiology studies of the hypothalamus in mice, scientists found that d-FEN doubles the firing rate in the POMC neurons, an effect reversed by drug washout. Morover, POMC neurons depolarized in response to receiving d-FEN, serotonin, or two serotonin receptor agonists.

The results support the notion that serotonin systems directly activate POMC neurons, causing them to increase their firing and release chemical messengers. Findings propose that d-FEN stimulates the release of serotonin in the ARC region of the hypothalamus. The neurotransmitter then binds to receptors in POMC neurons. These receptors in turn stimulate the release of a peptide molecule that acts on melanocortin receptors, critical regulators of energy, appetite, and various hormones in the brain.

Components of the anorexic effects of d-FEN are mediated through the central melanocortin system, which is now well established as a fundamental regulator of food intake and body weight in rodents and humans, reported the researchers in Science.

The melanocortin circuit is implicated in both anorexia and obesity. "Our work gives a mechanistic explanation of how drugs like D-FEN may inhibit food intake. Investigating the neurobiology of drug-caused anorexia may lead to the development of new drugs with fewer side effects to prevent and treat obesity," Elmquist stated.

Also participating were lead author Lora K. Heisler and Michael A. Cowley, Laurence H. Tecott, Wei Fan, Malcolm J. Low, James L. Smart, Marcelo Rubinstein, Jeffrey B. Tatro, Jacob N. Marcus, Henne Holstege, Charlotte E. Lee, and Roger D. Cone.

This research was funded by grants from the National Institute of Mental Health (NIMH) and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) with support from the National Alliance for Research on Schizophrenia and Depression, the International Scholar Program of the Howard Hugest Medical Institute, and the Agencia Nacional de Promocion Cientifica y Technologia.

NIMH and NIDDK are part of the National Institutes of Health (NIH), the Federal Government's primary agency for biomedical and behavioral research. NIH is a component of the U.S. Department of Health and Human Services.