Inhalation anesthetic abuse

Four types of inhalants are abused (1) anesthetic gases (2) industrial solvents, including a variety of hydrocarbons, such as toluene (3) aerosol propellants, such as various fluorocarbons and (4) organic nitrites, such as amyl or butyl nitrite. The mode of action of the inhalant anesthetics has been discussed in Chapter 25 General Anesthetics. 

The fact that there are so many different compounds abused as inhalants brings up question of how all of these compounds act on the brain. Do they all act in the same way The answer to this question will be discussed in Chapter 4. It has been argued by some researchers that inhalant abuse should be regrouped as solvent abuse, volatile anesthetic abuse, and nitrite abuse, since the populations that abuse these substances are different." Solvents are primarily abused by teenagers, anesthetics are generally abused by older professionals who have access to them, and nitrites are abused by populations older than teenagers. In the case of nitrites, as will be discussed later, the way the chemical acts upon the body appears to be quite different as well. In this book, the differences between these subgroups of inhalants will be discussed when useful. 

Chenoweth MB Abuse of inhalation anesthetic drugs, in Review of Inhalants Euphoria to Dysfunction. Edited by Sharp CW, Brehm ML. Washington, DC, U.S. Government Printing Office, 1977, pp 102-111 Clinger OW, Johnson NA Purposeful inhalation of gasoline vapors. Psychiatr Q 25 557-567, 1951... 

Other anesthetics susceptible to abuse, such as ether and chloroform, have received far less attention, because they are considered to be less commonly abused substances. Nonetheless, when inhaled, ether and chloroform are also rapidly absorbed and distributed in the central nervous system (CNS), inducing a rapid euphoria. Ether and chloroform inhalation is facilitated by the fact that they have a low boiling point (i.e., approximately 34°C) (Delteil et al. 1974). 

Toluene, volatile nitrites, and anesthetics, like other substances of abuse such as cocaine, nicotine, and heroin, are characterized by rapid absorption, rapid entry into the brain, high bioavailability, a short half-life, and a rapid rate of metabolism and clearance (Gerasimov et al. 2002 Pontieri et al. 1996, 1998). Because these pharmacokinetic parameters are associated with the ability of addictive substances to induce positive reinforcing effects, it appears that the pharmacokinetic features of inhalants contribute to their high abuse liability among susceptible individuals. 

Inhalation of other general anesthetics susceptible to abuse, such as ether and chloroform, appears to be limited to health professionals who have easy access to these compounds and who tend to use these dtugs in isolation. Recreational and social use of these substances has been somewhat limited by their high flammability and by frequent and intense undesirable adverse effects at moderate doses. It has been suggested that the abuse of ether or chloroform alone is a rare phenomenon (Delteil et al. 1974 Deniker et al. 1972), occurring usually in the context of dependence on othet substances, particularly alcohol (Krenz et al. 2003). 

From an socioeconomic perspective, inhalant abuse is most often associated with poverty, but there are abusers in all classes. Older inhalant users may develop abuse problems because they have access to volatile chemicals and anesthetics at the workplace. 

Based on their studies of animals, scientists believe that, in general, when toxic vapors circulate to the brain, they depress the central nervous system. The action is similar to that of alcohol, sedatives, and anesthetics. Thus, many of the immediate physical changes inhalant users experience are similar to those caused by alcohol or anesthetics, including relaxation, slurred speech, slowed reflexes, lack of coordination, sleepiness, dizziness, headache, nausea, and vomiting. Abusers might also sneeze, cough, and drool. 

Nitrous oxide is difficult to categorize. Technically, it is an inhalant, yet there are several characteristics that set the drug apart from the typical volatile substances that inhalant abusers favor. First, N20 is not as readily accessible as hair spray, glue, household cleaners, and other off-the-shelf huffing chemicals of choice. Secondly, since nitrous oxide is an actual prescription anesthetic, it may have more perceived prestige among users who would look down at most volatile substance abuse as kid s stuff. ... 

One of the major problems with why inhalants are so poorly understood is that little scientific focus has been aimed at understanding how inhalants affect the brain and behavior. Previous research on inhalants has focused more on organ toxicity caused by inhalants, the trends in inhalant use, and their anesthetic functions. Understanding inhalant abuse at the cellular and molecular level has been a neglected field. Since there have been a number of studies on the cellular basis for inhalant abuse in the past five years, this is hopefully an indication that future research will focus more on this area. 

Camphor has been used as a substance of abuse for many centuries, both by ingestion and by inhalation. Today it is found in many non-prescription vaporized or topical cold cures, topical musculoskeletal anesthetic... 

Phencyclidine is an anesthetic, analgesic, hallucinogenic drug which was widely abused in the 1970 s. As a street drug it was known as "peace pill", "crystal", "hog" and most commonly "PCP" or "angel dust" [161]. It is often used in combination with other illicit drugs and may be smoked, inhaled, snorted, or taken by injection. The abuse of phencyclidine has been associated with respiratory depression, convulsions, hyperpyrexia, hypertensive crisis and schizoid psychoses. 

Nitrous oxide is used therapeutically as an anesthetic or analgesic. It is also used in the formulation of rocket fuel and as a propellant for whipped cream. It occurs endogenously. Nitrous oxide is a common inhalant drug of abuse. 

A form of substance abuse of increasing interest is the recreational use of inhalants. Taken literally, this classification is useless, as it may be construed to include use of tobacco, crack cocaine, or marijuana (Sharp 1992). A better designation may be "volatile substance" abuse, a more accurate description of an important drug abuse pattern. Volatile substances that are commonly abused include glues, aerosols, anesthetics, cleaning agents, and solvents (Sharp 1992). Abuse of inhalants has been associated with a variety of toxicologies... 

The choice of a chromatographic method may be dependent on the intended use. The appropriate method when the intent is to establish a general screen for inhalant abuse may be very different from the method chosen to monitor administration of a particular anesthetic or exposure to industrial chemicals in the workplace. Likewise, forensic applications may vary from a general screen to post-mortem quantitation of particular suspected VOCs in blood and tissues. The number of methods developed for specific purposes (or compounds) is beyond the scope of this chapter, but it is hoped that the information provided will assist the analyst in finding or adapting chromatographic methods suitable for their particular situation. 

The macromolecular complex containing GABA-regulated chloride channels also may be a site of action of general anesthetics, ethanol, inhaled drugs of abuse, and certain metabolites of endogenous steroids. 

Nitrous oxide (N2O), also known as laughing gas, is one of the most common abused inhalants. It is an anesthetic gas. Inhalation can produce euphoria, dreaminess, tingling, numbness, as well as visual and auditory hallucination. Such effects arise from administering the gas diluted in oxygen, usually 30-35% mixed in oxygen. Inhalation of 100% N2O can cause asphyxiation and death. Many volatile organic compounds that have anesthetic properties can produce exhilaration and euphoria. These include diethylether, chloroform, and halothane. High doses of these substances can produce unconsciousness. 

Inhalants Volatile substances that are abused by inhalation and that produce effects similar to anesthetics. 

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