The illicit practice of smoking COCAINE is generally referred to as freebasing. The hydrochloride form of cocaine (powder) is highly soluble in water and, therefore, is efficiently absorbed by the mucous membranes when taken intranasally (snorted) or via blood when injected intravenously (shot up). This form of cocaine is, however, destroyed when it is heated to the temperatures required for smoking it. Therefore, the cocaine alkaloid, called "CRACK" or "freebase," is the form that is smoked. Although not always differentiated, freebase actually refers to cocaine in the base state with all the adulterants removed (Inciardi, 1991). Cocaine hydrochloride is combined with an alkaline substance, such as sodium hydroxide or ammonia, to remove the hydrochloride. The free cocaine base is then dissolved in ether, and pure cocaine-base crystals are formed. It has been estimated that approximately 560 milligrams of cocaine freebase can be extracted from one gram of street cocaine hydrochloride (Siegel, 1982). Cocaine freebase has a melting point of 208 F (98 C) and is volatile at temperatures above 194 F (90 C), therefore providing an active drug for smoking. Crack, in contrast, although also in the base state and used for smoking (or freebasing), does not have the adulterants of the street cocaine removed. Cocaine base is soluble in alcohol, acetone, oils, and ether—but is almost insoluble in water.
Cocaine freebase is usually smoked in a water pipe containing fine mesh screens, which trap the heated cocaine as it melts. A temperature of 200 F (93 C) is the most efficient. Although the amount of cocaine absorbed by the smoker varies—depending on the kind of pipe used, the temperature of the heat source, and the inhalation pattern of the user—under optimal conditions approximately 30 to 35 percent of the cocaine placed on the mesh screen is absorbed by the smoker.
Comparison of Cocaine and Methamphetamine Smoking
Vapor inhalation of the () isomer of methamphetamine hydrochloride, colloquially known as ice has several differences when compared to vapor inhalation of cocaine freebase. Although both methamphetamine and cocaine freebase have their origin as a salt, cocaine hydrochloride must be pretreated with an alkaline substance to remove the hydrochloride, thus creating the freebase of cocaine that can be heated and inhaled as vapor. In contrast, methamphetamine hydrochloride can be heated and inhaled without adulterating the original compound.
When heated, cocaine freebase has a melting temperature of 208 F while methamphetamine hydrochloride melts at 268 F. Once the appropriate melting temperature is met for each substance, vapors will form and can be inhaled. Significant amounts of cocaine freebase vapor are lost through pyrolysis (chemical change caused by heat) and little condensation appears on the water pipe, suggesting decreased amounts of inhaled vapor. Meth-amphetamine hydrochloride, however, condenses as a crystalline solid on the cooler areas of the glass pipe. It is thought that this same phenomenon occurs in the mouth and throat of the user, leading to rapid methamphetamine absorption through the lungs as well as delayed absorption through the oral mucosa.
These differences in drug absorption have been demonstrated by comparisons of plasma levels of cocaine and methamphetamine after smoking the individual substances. Plasma levels of cocaine peak and decline rapidly, with a half-life of approximately forty-five to sixty minutes. Methamphetamine plasma levels also rise rapidly, but the half-life is approximately eight to twelve hours. The delayed absorption of methamphetamine from the oral mucosa is thought to play a role in the extended half-life. Differences in the metabolism of cocaine and methamphetamine also contribute to the disparity in plasma half-life. Cocaine is quickly degraded to inactive metabolites by plasma esterases (enzymes) and cleared from the bloodstream. Methamphetamine is eliminated by enzymes with limited plasma distribution and limited activity and, unlike cocaine, is converted to active metabolites that prolong the action of the drug. These active metabolites can accumulate, and repeated smoking of methamphetamine and its active metabolites can lead to dangerous levels of methamphetamine in the plasma.
In summary, differences between cocaine free-base vapor inhalation and methamphetamine hydrochloride inhalation include method of preparing the substance, melting temperature, metabolism, and length of plasma half-life. These differences can have important clinical implications. For example, methamphetamine can cause paranoid symptoms that last considerably longer than those ordinarily seen after cocaine smoking. Distinguishing between drug-induced paranoia and other causes of paranoia thus requires a different length of drug-free observation depending on which drug was inhaled. Understanding the differences between cocaine freebase inhalation and methamphetamine inhalation, particularly the difference in duration of action of the two drugs, can be important in the evaluation and management of patients with stimulant abuse.
Although in use since the mid-1970s, freebasing cocaine became popular in the United States in the early 1980s. The popularity of this route of administration was responsible for the rise in U.S. cocaine use during the mid-1980s. When cocaine is smoked, it is rapidly absorbed and reaches the brain within a few seconds. Thus, users get a substantial immediate rush and an almost instant "high," comparable to that after intravenous cocaine. This is in contrast to intranasal use of cocaine, which engenders a high with a much slower onset. Freebasing is thus a convenient way of taking cocaine, with the possibility of repeated and substantial doses. Since the likelihood of abuse is related to the rapidity with which a drug reaches the brain, smoking cocaine makes it more likely that use will lead to abuse than does snorting the drug. Despite losses of more than half of the cocaine when it is smoked, sufficient cocaine rapidlyreaches the brain, providing an intense drug effect—which users repeat, often to toxicity. The danger of freebasing, in addition to the inherent danger of cocaine use, lies in what some users perceive to be the greater social acceptability of a route of administration that requires minimal PARAPHERNALIA and can achieve toxic levels of cocaine with relative ease.
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COOK, C. E. (1982). Pyrolytic characteristics, pharmacokinetics, and bioavailability of smoked heroin, cocaine, phencyclidine, and methamphetamine. In M. A. Miller & N. J. Kozel (Eds.), Methamphetamine abuse: Epidemiologic issues and implications, 6-23. NIDA Research Monograph no. 115. Rockville, MD: National Institute on Drug Abuse.
INCIARDI, J. A. (1982). Crack-cocaine in Miami. In S. Schober & C. Schade (Eds.), The epidemiology of cocaine use and abuse. NIDA Research Monograph no. 110. Rockville, MD: National Institute on Drug Abuse.
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