Central Nervous System Stimulants

Drug Types

The CNS stimulants are distinguished by their unique pharmacologies (i.e., mechanism of action, especially on the CNS), potencies, and access. Briefly, the stimulants can be classified as major and minor. The major stimulants include drugs such as the amphetamines (e.g., amphetamine, methamphetamine, and ecstasy) and cocaine. These drugs can exert powerful stimulation on both the brain and the cardiovascular systems when used in moderate to high doses. It is common to hear users describe their first exposure to these drugs as "the greatest feeling they ever experienced." This reaction almost certainly reflects the ability of these drugs to dramatically and rapidly activate the brain's pleasure systems and to cause a dramatic release of the neurotransmitter dopamine from brain cell terminals located in a brain region known as the nucleus accum-bens. Also interesting is that most of those addicted to these stimulants also claim that they are never able to duplicate the intensity ofthat first stimulant experience no matter how often they administer the drug or how high a dose they use. In fact, with continual stimulant exposure, the brain's pleasure pathway appears to be compromised even for nondrug-related naturally occurring rewards making it difficult for the user to find enjoyment in activities that used to be pleasurable. The positive properties of the stimulants tend to diminish until the user must repeatedly administer the stimulant just to achieve a normal level of natural reward. Typically, when the stimulant-dependent person reaches this stage, abstinence from the drug can lead to severe depression and in extreme cases, suicide ideation or even attempts. This stimulant-induced downward spiral of pleasure function reinforces continued stimulant use and can lead to severe dependence and even episodes of intense and dangerous bingeing with these drugs. Although there are many similarities between the amphetamines and cocaine, there also are significant clinical and practical differences. For example, cocaine is a naturally occurring substance that is extracted from the coca plant found only in the Andes mountains of South America. Consequently, all cocaine (both legal and illegal) used in the United States must be shipped across the borders of this country. After administration of cocaine (especially intravenous injection or by smoking routes), it enters the brain rapidly and exerts CNS effects within seconds. Cocaine is also metabolized rapidly, and the pharmacological actions disappear after a few minutes. In [Page 167]contrast, the amphetamines such as methamphetamine are synthetics that can be made by relatively unsophisticated chemistry; thus, it is common to see local methamphetamine labs "cooking" this stimulant and selling the products on the streets. These labs use over-the-counter decongestant ingredients such as pseu-doephedrine as starter material. The synthesis requires toxic and potentially lethal chemicals. As a result, the methamphetamine labs are a significant hazard to occupants of the building where the lab is located, neighboring buildings, and enforcement or cleanup personnel who enter the premise. In order to close or prevent the methamphetamine labs, law enforcement agencies at the federal, state, and local levels have controlled access by the general public to the precursor decongestant and cold products. This control is achieved by requiring pharmacies and stores that sell such products to keep them behind the counter and to limit the number of boxes sold to individuals. This effort has been extremely effective in shutting down the local "mom and pop" labs, but has had little impact on imported methamphetamine from Mexico, Asia, or other foreign sources. Consequently, methamphetamine is still readily accessible, relatively inexpensive, and its abuse is a major problem for many regions in this country.

...