Most pharmacological treatments of obesity and weight loss programs focus on lowering the energy intake and resort to anorectic drugs that modify the metabolism of brain neurotransmitters involved in appetite regulation. Appetite suppressants are used to decrease appetite or increase the feeling of being full in overweight patients by possibly increasing levels of serotonin or catecholamine which’re brain chemicals that effect mood and appetite. Because the brain plays an essential role in the control of appetite, researchers have looked at various neurotransmitters, specifically serotonin, dopamine and nor-epinephrine. This class of weight control drugs act on the central nervous system (CNS) to suppress appetite. One major subclass of CNS appetite suppressant drugs interacts with cathecolaminergic receptors in the brainstem. These include controlled drugs such as amphetamine, phenmetrazine, and diethylproprion.

A number of prescription and over-the-counter weight loss products have been developed which influence these neurotransmitters, thereby reducing appetite. The anorexiant medications affect neurotransmitter activity by acting on either the catecholaminergic system (amphetamines, phendimetrazine, phentermine, benzphetamine, mazindol, diethylpropion, and phenylpropanolamine) or the serotonergic system (dexfenfluramine, fluoxetine, fenfluramine, sertraline, and other antidepressant selective serotonin reuptake inhibitors. Serotonin is a natural neurotransmitter involved in brain systems controlling sleep, sex drive and satiety. Fenfluramine is another class of anorexiant drug that is a potent releaser of serotonin from serotonergic neurons impinging on the cerebral appetite center. When combined with phentermine, fenfluramine is reported to have the effect of enhancing and extending the anorexiant action of phentermine. Phenylpropanolamine (PPA), amphetamines and fenfluramine alone or in combination with caffeine. Caffeine functions probably to reduce fatigue as caffeine has stimulating properties. Phenylpropanolamine (PPA) is a popular over-the-counter drug for appetite suppression and its side effects are well documented.

Ephedrine is an indirect-acting sympathicomimetic agent that enhances the release of norepinephrine from sympathetic neurons and stimulates alpha and beta receptors. Ephedrine can be extracted from the herb Mahuang (Ephedra sinica). St. John’s Wort is a herb of the hypericaceae family, it contains the therapeutically active ingredient hypericin. The herb Wort may be used for weight reduction and appetite suppressant. Alternatively, hypericin, the active ingredient of St. John’s Wort may be extracted from the herb by soaking the crushed herb in an alcohol/water solution and the extracted active ingredient dried by spray drying or evaporation.

Appetite suppressants generally modulate neurotransmitter function in the central nervous system are known to act by increasing the availability of catecholamines, in particular noradrenaline, in certain areas of the brain, hence resulting in perceived suppression of hunger or reduced apetite. By suppressing appetite, less food is eaten, and caloric intake is lowered. However, reducing appetite pharmacologically has a number of drawbacks, including a decrease in the weight loss efficacy of the medication over a period of time. Drugs that affect neurotransmitters also affect the central nervous systems and thus may result in jitteriness and anxiety. In addition, these appetite suppressing agents can produce cardiovascular effects that may have very serious consequences.