Appetite suppressants are a group of sometimes very different active ingredients that aim to reduce weight. The way in which this goal is achieved varies. The few drugs that are approved for the treatment of overweight or are in development can be roughly divided into three groups according to their mechanism of action:
- The first group achieves weight reduction by reducing appetite or increasing the feeling of satiety.
It acts directly on the central nervous system (CNS), the hypothalamus. – A second group inhibits the absorption of certain food components, especially fats, in the intestine. – A third group consists of active ingredients that are similar in structure to endogenous hormones from the gastrointestinal tract and thus mimic their action. There are other active substances with different mechanisms, some are currently being tested for the treatment of obesity, others are not indicated for the treatment of obesity but have different indications. For example, thyroid hormones (thyroxine) increase the basal metabolic rate, which leads to a faster breakdown of calories supplied.
As the name suggests, the use of Antiadiposita is reserved for the group of patients with overweight. Overweight in the sense of obesity (obesity) is, by definition, defined as a body mass index of 30 kg/m2 or more, but patients with a BMI above 25 kg/m2 or 28 kg/m2 may also require treatment if they already have other risk factors for the cardiovascular system (cardiovascular risk factors) such as high blood pressure or very high cholesterol levels (hypercholesterolemia). The more these risk factors a patient has, the higher the risk of cardiovascular disease, for example
- Coronary heart disease
- Heart attack or
Approved active substances
In Germany, four active ingredients are currently approved for the treatment of obesity. Orlistat reduces the absorption of fats in the gastrointestinal tract by inhibiting the enzymes (lipases) responsible for fat splitting. In studies it has been combined with a fat-reduced diet.
The weight loss of patients who followed a diet and took orlistat was compared to those who followed a diet and took a placebo (drug that looked like orlistat but contained no active ingredient). Weight loss was seen in both groups in some patients, but in the orlistat group, the rate of patients losing weight was higher. However, the studies also showed that the patients who lost weight under orlistat had regained their initial weight within one year of stopping the drug.
In the patients examined, the concentration of unfavourable LDL cholesterol decreased under treatment with orlistat, while that of favourable HDL cholesterol increased. Furthermore, a decrease in the fasting blood sugar level and blood pressure was observed. Orlistat thus had a positive effect on many cardiovascular risk factors.
Orlistat should not be taken for more than six months at a time. Unless a weight reduction of at least 5% of the initial weight is seen after 12 weeks, treatment should be discontinued. The side effects are mainly those directly related to the increased excretion of fat in the stool, such as lower abdominal pain, flatulence with stool discharge and urge to defecate up to faecal incontinence.
The rate of side effects increases with a high-fat diet, which is another reason why a low-fat diet should be followed. Orlistat is available without prescription in pharmacies at a price of about 32 euros for 42 capsules of 60 mg each or 44 euros for 84 capsules of 60 mg each. Currently, three more appetite suppressants are approved in Germany, all three of which attack directly in the central nervous system (CNS) and belong to the group of amphetamines: Amfepramone, phenylpropanolamine (also: Norephedrine) and D-Norpseudoephedrine (also: Cathine).
These drugs release certain messenger substances (neurotransmitters) such as (nor)adrenaline from nerve cell endings and thus belong to the group of indirect sympathomimetics, i.e. they stimulate the sympathetic nervous system and thus increase heart rate and blood pressure. On the one hand, these messenger substances increase the energy metabolism by activating the sympathetic nervous system, on the other hand they act via appetite inhibition. The spectrum of side effects of sympathomimetics is large because they do not only act where it is desired.
The duration of application is therefore – depending on the drug – limited to four to a maximum of 12 weeks. Due to the sometimes dramatic side effect profile, the use of one of these drugs should be thoroughly considered under a precise benefit-risk assessment. 30 capsules with the active ingredient ampepramone cost about 29 euros (Regenon®), 30 capsules with the active ingredient phenylpropanolamine cost about 29 euros (Recatol®), 15 ml with the active ingredient norpseudoephedrine cost about 25 euros (Alvalin®).
- Cardiac arrhythmia
- High pressure in the pulmonary vessels (pulmonary hypertension)
- Psychological disorders up to psychoses (drug psychosis)
Other active ingredients have been and are being tested for their effectiveness in experimental studies. For example, drugs from the group of reuptake inhibitors of serotonin, noradrenalin and dopamine (e.g. tesofensin). Furthermore, active substances are currently being tested which are similar to hormones of the gastrointestinal tract and some of which are already used in the treatment of diabetes mellitus (e.g. exenatide).
A combination of the amphetamine phentermine and the antiepileptic drug topiramate is also currently being tested in studies. So far, this combination preparation has been found to be more effective than orlistat, with less severe adverse effects. In addition to these drugs, there are still numerous herbal remedies or alternative medicine products that can be used for weight reduction.
It should be noted that herbal remedies are not always harmless. Such active ingredients can also have serious side effects, especially if they are used improperly and without medical supervision. The group of herbal appetite suppressants includes “natural stimulants” such as
- Caffeine, mate or black tea
- Ballast and swelling agents such as guar and flea seeds and
- Active ingredients that increase energy metabolism (herbal sympathomimetics) such as ephedrine