Central nervous system stimulants include ephedrine, caffeine, etc. This type of drug can stimulate fat oxidation and increase energy consumption, and because it can excite the central nervous system, it can actually suppress appetite, but it often requires a larger dose to achieve weight loss. Some experimental studies believe that ephedrine can effectively promote the release of catecholamine transmitters, excite adrenergic receptors, and promote thermogenesis. However, the effect of ephedrine in promoting thermogenesis is weakened by the negative feedback regulation of the adenosine-prostaglandin and cAMP phosphodiesterase systems. Methylxanthines and aspirin that affect these systems can enhance the effect of ephedrine.
Ephedrine can produce an excitatory effect on the central nervous system, causing excitement, restlessness, anxiety, insomnia, tremor, etc. It can also increase blood pressure, causing headaches, palpitations, increased myocardial contraction, increased sweating, etc. It is contraindicated in patients with hyperthyroidism, hypertension, arteriosclerosis, angina pectoris, etc.
Do not use it in combination with monoamine oxidase inhibitors to avoid causing high blood pressure. Repeated use in a short period of time can produce tachyphylaxis and weaken the effect, which can be restored within a few hours of drug withdrawal.
Caffeine can promote fat decomposition, increase heat production, and reduce weight. These effects are achieved by antagonizing adenosine receptors. Adenosine receptors are widely found in the central nervous system, sympathetic nerve endings and the effector organs they innervate, and are divided into three types: A1, A2 and A3. When it is excited, it can produce a wide range of biological effects, causing changes in the function and metabolism of the central nervous system, cardiovascular system, respiratory system, gastrointestinal system.
Adenosine A1 receptor stimulation can produce sedation, inhibit transmitter release, inhibit lipolysis, have antidiuretic effects, and can constrict blood vessels, produce bradycardia, and weaken myocardial contraction.
A2 receptor stimulation can produce effects such as decreased muscle motility, vasodilation, and glycogen production.
Caffeine is a non-selective adenosine receptor antagonist. After application, it can excite the central nervous system by antagonizing adenosine receptors, promote the release of catecholamine transmitters, and increase the decomposition of fat and glycogen. Excites the cardiovascular system and produces a diuretic effect.
These effects of caffeine can lead to loss of appetite, enhanced catabolism, and weight loss, but sensitive patients are prone to adverse reactions such as anxiety, excitement, insomnia, incoherent speech and thinking. For some patients who are prone to anxiety and mania, even moderate amounts of caffeine can induce anxiety, fear or mania. High doses (gt; 600 mg daily) can produce a syndrome similar to an anxiety state, manifesting as anxiety, restlessness, and insomnia.
The lethal dose of caffeine is 5 to 10g, but severe poisoning reactions are very rare. Patients with myocardial ischemic disease should use with caution. Caffeine can block adenosine receptors, so it has a synergistic effect when combined with ephedrine. When the two are mixed in a certain proportion (ephedrine 20mg, caffeine 200mg), the thermogenic and appetite suppressing effects are enhanced. When administered 3 times a day, supplemented with a low-calorie diet, it can significantly reduce body fat, and can alleviate the symptoms of energy loss caused by a low-calorie diet. There are only minor side effects such as hand tremors, insomnia, and dizziness. The drug is already available in Denmark. In our country, it is not used as a routine weight loss drug.