Differences Between Methamphetamine and Cocaine
Methamphetamine and cocaine are two illegal drugs that belong to a class of substances called stimulants. Virtually all substances in this class produce significant changes in mental and physical function by altering normal rates of activity in both the central nervous system and a network of involuntary nerves known as the sympathetic nervous system. Despite their basic similarities as stimulant drugs of abuse, methamphetamine and cocaine differ from each other in important ways, including the degree of change they produce in the central nervous system, their duration of activity within the brain and body, and their ability to trigger a drug overdose.
Methamphetamine is a manmade drug that belongs to a group of natural and synthetic substances called substituted amphetamines. Like all substances within this group, every molecule of methamphetamine contains an amphetamine backbone connected to additional atoms of specific chemical elements. There are two main forms of meth, known as l-methamphetamine (levomethamphetamine) and d-methamphetamine (dextromethamphetamine). L-methamphetamine produces bodily effects through activation of the sympathetic nervous system, but produces no mind-altering changes in the central nervous system; this form of the drug is not illegal. D-methamphetamine produces profound mind alteration in the central nervous system, as well as strong activation of the sympathetic nervous system. A combined mixture of l- and d-methamphetamine, called dextro-levomethamphetamine, is more powerful than l-methamphetamine but less powerful than d-methamphetamine. The vast majority of meth abusers and addicts use illegally manufactured d-methamphetamine; this drug is also available in a legal form called methamphetamine hydrochloride (Desoxyn).
Cocaine’s full chemical name is benzoylmethylecgonine. While the finished form of the drug is a manmade product, it has its origins in the coca plant, Erythroxylum coca, as well as in several closely related plant species. Chemical modification turns coca leaf into a powdered substance called cocaine hydrochloride, which users of the drug can nasally inhale (snort), swallow, or mix with liquid and inject into a vein. Illicit drug manufacturers make a second form of cocaine, commonly known as “crack,” by chemically altering cocaine hydrochloride. This alteration produces little rock-like nuggets of the drug; crack users ignite these nuggets and inhale the resulting fumes into their lungs.
Activity in the Brain
Both methamphetamine and cocaine achieve their basic mind-altering effects by artificially increasing the amount of a neurotransmitting chemical, called dopamine, found in a region of the brain called the limbic system. Structures in this system are responsible for producing the human ability to feel pleasure, and the level of pleasure experienced by the individual goes up when dopamine supplies rise. Dopamine levels can rise in one of two basic ways. First, the cells in the brain that produce this neurotransmitter can be forced to increase their rate of dopamine output. In addition, levels of the chemical will rise whenever something blocks the natural breakdown and recycling process that removes existing dopamine from active circulation.
Methamphetamine and cocaine both increase dopamine supplies by blocking the normal breakdown and recycling of the chemical. However, unlike cocaine, methamphetamine also forces the dopamine-producing cells in the brain to increase their dopamine output. As a result of this dual activity, methamphetamine use triggers a significantly higher increase in dopamine levels than cocaine use. According to researchers at the University of Arizona, any given amount of methamphetamine triggers at least three times the dopamine boost triggered by an equivalent amount of cocaine.
Duration of Activity
Drugs lose their effect in the body when they get broken down (metabolized) and eliminated from circulation. Half of any given dose of cocaine gets metabolized and eliminated within approximately one hour, while it takes approximately 12 hours for the body to metabolize and eliminate an equivalent amount of methamphetamine. In real-world terms, this means that a person who smokes crack cocaine will feel “high” for roughly half an hour, while a person who smokes an equivalent amount of crystal meth will feel “high” for anywhere from eight hours to a full day. Because of its prolonged presence in the brain, methamphetamine has a greater tendency than cocaine to produce negative changes in normal consciousness. For instance, meth users develop symptoms of psychosis (which can include hallucinations and/or delusional thinking) considerably more frequently than cocaine users.
Both methamphetamine and cocaine are capable of producing an overdose in new users, as well as in habitual users who exceed their usual levels of drug intake. However, cocaine use presents an additional risk for the onset of an overdose. While long-term methamphetamine abusers can more or less accurately gauge how much of the drug they can tolerate at one time, long-term cocaine users can develop unexpected sensitivities to their accustomed drug dosage. Effectively, this means that all cocaine users have unpredictable risks for experiencing an overdose, regardless of how much of the drug they take at any given time.