Салмақ түсіру және стимулятор ретінде қолданылатын препараттар комбинациясы

Drug combination used in weight loss and as a stimulant
The ECA stack is a drug combination used in weight loss and as a stimulant. ECA is an initialism for ephedrine, caffeine, and aspirin, with variants of it including the EC stack, which removes the aspirin for those who can not tolerate it. Dietary supplements based on or including elements of ECA were popular through the 1990s and early 2000s, but the marketing of ephedra or ephedrine containing stimulant combinations for weight loss and bodybuilding is now restricted or illegal in the United States and the Netherlands due to reports of heart attack, stroke, and death associated with these supplements. A meta analysis combining results from all available studies estimated average weight loss of 1 kg/month more than placebo. A 2003 meta analysis of all available studies and case reports concluded that: "ephedrine and ephedra containing dietary supplements [ ] have harms in terms of a 2 to 3 fold increase in psychiatric symptoms, autonomic symptoms, upper gastrointestinal symptoms, and heart palpitations. More serious adverse effects from ephedra use cannot be excluded at a rate less than 1.0 per thousand, and case reports raise the possibility that a causal relationship with serious adverse events may exist."

Clinical trials indicate that the most effective dose is approximately 20mg of ephedrine and 200mg of caffeine, while the most effective dose of aspirin has not been well studied. However, this dosage has not been recommended by regulatory agencies such as the FDA and do not take into consideration mitigation of adverse side effects. Increased circulating norepinephrine in the body then acts on brown adipose tissue and skeletal muscle by increasing cyclic adenosine monophosphate (cAMP) levels. This causes a thermogenic effect, raising bodily heat production and increasing energy consumption in conjunction with the rest of the stack. However, the body's negative feedback systems quickly activate to normalize metabolism. This takes the form of elevated phosphodiesterase enzyme activity within the cells, as well as prostaglandin release in the synaptic junctions; both of these degrade cAMP and mitigate the thermogenic effects. Caffeine inhibits the production of phosphodiesterase inside the cell and therefore slows the degradation of cAMP. Aspirin inhibits prostaglandin production outside of the cells, which, in conjunction with caffeine, greatly prolongs the thermogenic effects and increased metabolism by sustaining elevated cAMP levels. The stimulating effects of caffeine and ephedrine are an additional contributing factor to weight loss. The stack's effect on the central nervous system results in increased aerobic exercise performance, measured as time until exhaustion relative to respiratory metrics.

Due to deaths linked to ephedra containing dietary supplements and the potential use of ephedrine as a precursor in illegal methamphetamine manufacture, many countries have taken steps to regulate these products.

In the United States, it is illegal to market products containing ephedrine or ephedra alkaloids as a dietary supplement. In 2004, ephedra, a botanical source of ephedrine alkaloids, was banned by the U. S. Food and Drug Administration due to serious safety concerns, injuries, and deaths linked to ephedra containing supplements. However, ephedrine itself has never been illegal in the United States and is currently available over the counter. Reporting requirements and quantity limitations vary by state. A Congressional report said that when an ephedra supplement company, Metabolife, in the USA was forced to release adverse event reports, cardiac and psychological reports were recorded in healthy young people at normal dosages.

In January 2002, Health Canada issued a voluntary recall of all ephedrine products containing more than 8 mg per dose, all combinations of ephedrine with other stimulants such as caffeine, and all ephedrine products marketed for weight loss or bodybuilding indications, citing a serious risk to health.

An EC formulation called Letigen which combined 20 mg of synthetic ephedrine and 200 mg of caffeine (recommended dose: 1 3 pills per day depending on user tolerance) was approved for sale by prescription in Denmark in 1990. During the peak of its use (in 1999) roughly 2% of the Danish population was using it.