Psychotropic Drugs

█ JUDYTH SASSOON

Psychotropic drugs are a loosely defined grouping of agents that have effects on psychological function and include the antidepressants, hallucinogens, and tranquilizers. They are all compounds that affect the functioning of the mind through pharmacological action on the central nervous system. Psychotropic drugs are ubiquitous in our society and encompass both prescription psychiatric medications and illegal narcotics, as well as many over the counter remedies. Because these compounds affect human behavior, there is much suspicion, misunderstanding, and controversy surrounding their use. Sedative drugs first appeared in the late 1800s. They were followed by barbiturates and amphetamines in the early 1900s. But it was drugs such as chlorpromazine hydrochloride (Thorazine) and lithium, introduced in the 1950s that dramatically affected psychiatric medicine. Medicine essentially recognizes four main psychotropic drug categories: antipsychotics, mood stabilizers, antianxiety agents and antidepressants.

Antipsychotics include chlorpromazine, which was released in 1954 for the treatment of schizophrenia. Originally designated as a major tranquilizer, it was also found to be effective in subduing the hallucinations and delusions of psychotic patients. Since then, other antipsychotics, including haloperidol (Haldol) and clozapine (Clozaril) were developed for the treatment of various kinds of psychosis. Mood stabilizers were first recognized following Australian psychiatrist John F. J. Cade's 1949 discovery of the beneficial effects of lithium on manic-depressive disorder. Patients with schizophrenia, however, did not respond to lithium, leading psychiatrists to a degree of diagnostic precision that was previously not possible. Recently, some antiepileptic medicines—valproic acid (Depakene) and carbamazepine (Epitol, Tegretol) have also been used to treat manic-depressive disorder. Barbiturates were widely prescribed before the 1960s to relieve anxiety, but were found to be highly sedating and addictive and did not always work successfully. Chlordiazepoxide (e.g. Librium) and the other benzodiazepine agents developed from the 1960s to the 1980s rapidly replaced barbiturates. Antidepressants are possibly the most widely used psychotropic drugs in the United States. In any given 6-month period, about 3 percent of adult Americans experience severe depression. For the millions whose depressed mood becomes a clinical syndrome, though, psychotropic therapy is one way to relieve the symptoms. The tricyclic imipramine hydrochloride (Tofranil), developed during the late 1950s and introduced during the early 1960s, was the first of the now-available antidepressants and still is often prescribed. Research has progressed considerably since then and current theories attribute depression to psychological causes (e.g. low self-esteem, important losses in early life, history of abuse) and biological causes (e.g. imbalance of neurotransmitters, including serotonin and dopamine; disruptions in the sleep-wake cycle) as well as experiential and social factors. The various classes of antidepressants, tricyclics, MAOIs, serotonin-specific agents, and individual drugs including nefazodone (Serzone), mirtazapine (Remeron), venlafaxine (Effexor), and bupropion hydrochloride (BuSpar) target the biological causes. At present, the selective serotonin reuptake inhibitors (SSRIs) hold center stage, and fluoxetine hydrochloride (Prozac) is in the spotlight. The result of years of focused research and design, fluoxetine was rapidly accepted and prescribed to millions within a few months after its introduction in December 1987.

Psychotropic drugs and law enforcement. Though much of the research and understanding of psychopharmacology comes from the field of medicine and psychiatry, there are of course, other areas where psychotropic drugs have been used, ranging from illegal recreational use to the possibility of applying them as agents of "mind control." The Central Intelligence Agency (CIA) Crime and Narcotics Center monitors, reviews, and delivers information about international trafficking in illegal drugs and international organized crime to the nation's leaders and law enforcement agencies. Former Director of Central Intelligence William Webster created what became today's DCI Crime and Narcotics Center in April 1989. The center is staffed by people from the 13 agencies making up the US Intelligence Community, including the CIA, as well as from law enforcement agencies. The Crime and Narcotics Center's staff are responsible for estimating the amount of illegal drugs, mainly coca, opium poppy, and marijuana, produced around the world. They also assist law enforcement agencies to break up drug and organized crime groups and help law enforcement agencies detect and capture illegal drug shipments.

The CIA's interest in psychotropic drugs does not end in law enforcement, however. MK-ULTRA was a CIA "mind-control" project backed during the Cold War years. Because the Soviets were supposedly researching a drug that could be used as a "truth serum," the CIA set out to beat them with heavily-funded research into consciousness altering drugs, and techniques of behavioral control. More recently, following the September 11, 2001, attacks on the World Trade Center in New York by al-Qaeda, there has been some discussion among some CIA and FBI staff, including William Webster, about the use of "truth drugs" to extract information from uncooperative terrorist suspects. United States Secretary of Defense Donald Rumsfeld asserted that narcoanalysis is not used by United States military and intelligence personnel, but suggested that other countries have made use of the technique in the interrogation of suspected terrorists. One such drug is sodium pentothal, which is used as a sedative and anaesthetic during surgery. It depresses the central nervous system, slows the heart rate and lowers blood pressure. Patients on whom the drug is used as an anaesthetic are usually unconscious less than a minute after it enters the veins. Because of its effectiveness as a sedative, it was also one of the first of three drugs to be used by the U.S. prison system during executions. In milder doses, the drug affects people such that they often become more communicative and share their thoughts without hesitation. Despite its name, however, sodium pentothal will not make a person tell the truth against their will; a recipient is only likely to lose inhibitions and therefore, may be more likely to volunteer the truth.

According to conventions set forth by the United Nations, the FBI and other U.S. law enforcement agencies disavow the practice of physically coercing or drugging prisoners, but point to the fact that many other countries around the world utilize drugs in interrogations. U.S. officials prefer to use psychology and investigative knowledge to extract information. Authorities are officially focused on making sure they obtain information without violating a suspect's constitutional rights because they do not want to jeopardize having such evidence ruled inadmissible in court. In attempting to prevent future acts of terrorism, however, authorities are sometimes focused more on obtaining quality information than they are on preparing cases for court, thus, in the present political situation, the FBI may be considering more aggressive methods of interrogation of terrorist suspects that might involve the use of psychoactive drugs.

A recent alleged use of a psychotropic drug by the U.S. was reported in the Russian newspaper, Komsomolskaya Pravda. In April 2001, it was reported that U.S. spies used drugged cookies and drinks to break the will of a Russian defense employee and recruit him as an agent. The employee was identified as a 58-year-old worker of a defense ministry facility near Zhukovsky air base, the Russian air force's top flight test center near Moscow. Whether accurate or not, the article illuminates the fact that the U.S. and Russia continue to show interest in spying on each other, despite better relations, and that psychotropic drugs may still play a part in espionage.

█ FURTHER READING:

BOOKS:

Maxmen, Jerrold S., and Nicholas G. Ward. Psychotropic Drugs: Fast Facts, 2nd ed. N.p., Norton & Company, 1995.

PERIODICALS:

Romanko, J. R. "Truth Extraction." New York Times Magazine. (November 19, 2000): 54.

SEE ALSO

Chemistry: Applications in Espionage, Intelligence, and Security Issues
CIA (United States Central Intelligence Agency)
FBI (United States Federal Bureau of Investigation)

Psychotropic Drugs

Determining the presence of various drugs in samples, including blood and urine, is an important facet of forensic science . A variety of analytical techniques can be used, depending upon the drug being tested. Eyewitness information concerning the behavior of the victim or suspect, and physical aspects of the investigation scene (i.e., presence of syringes, open liquor bottles, or the smell of marijuana), can guide the law enforcement officer or forensic investigator in recommending particular drug tests.

Psychotropic drugs are forensically relevant. The drugs are a loosely defined grouping of agents that have effects on psychological function and include antidepressants, hallucinogens, and tranquilizers. They are all compounds that affect the functioning of the mind through pharmacological action on the central nervous system. Psychotropic drugs are widespread in today's society and encompass both prescription psychiatric medications and illegal narcotics, as well as many over the counter remedies. Because these compounds affect human behavior, there is much suspicion, misunderstanding, and controversy surrounding their use. Sedative drugs first appeared in the late 1800s. They were followed by barbiturates and amphetamines in the early 1900s. But it was drugs such as chlorpromazine hydrochloride (Thorazine) and lithium, introduced in the 1950s, that dramatically affected psychiatric medicine. Medicine essentially recognizes four main psychotropic drug categories: antipsychotics, mood stabilizers, antianxiety agents, and antidepressants.

Antipsychotics include chlorpromazine, which was released in 1954 for the treatment of schizophrenia. Originally designated as a major tranquilizer, it was also found to be effective in subduing the hallucinations and delusions of psychotic patients. Since then, other antipsychotics, including haloperidol (Haldol) and clozapine (Clozaril) were developed for the treatment of various kinds of psychosis.

Mood stabilizers were first recognized following Australian psychiatrist John F. J. Cade's 1949 discovery of the beneficial effects of lithium on manic-depressive disorder. Patients with schizophrenia, however, did not respond to lithium, leading psychiatrists to a degree of diagnostic precision that was previously not possible. Recently, some antiepileptic medicines—valproic acid (Depakene) and carbamazepine (Epitol, Tegretol) have also been used to treat manic-depressive disorder.

Barbiturates were widely prescribed before the 1960s to relieve anxiety, but were found to be highly sedating and addictive and did not always work successfully. Chlordiazepoxide (Librium) and the other benzodiazepine agents developed from the 1960s to the 1980s rapidly replaced barbiturates.

Antidepressants are possibly the most widely used psychotropic drugs in the United States. In any given six-month period, about 3% of adult Americans experience severe depression. For the millions whose depressed mood becomes a clinical syndrome, though, psychotropic therapy is one way to relieve the symptoms. The tricyclic imipramine hydrochloride (Tofranil), developed during the late 1950s and introduced during the early 1960s, was the first of the now-available antidepressants and still is often prescribed. Research has progressed considerably since then and current theories attribute depression to psychological causes (low self-esteem, important losses in early life, history of abuse) and biological causes (imbalance of neurotransmitters , including serotonin and dopamine; disruptions in the sleep-wake cycle) as well as social factors. The various classes of antidepressants—tricyclics, MAOIs, serotonin-specific agents—and individual drugs—including nefazodone (Serzone), mirtazapine (Remeron), venlafaxine (Effexor), and bupropion hydrochloride (BuSpar)—target the biological causes. At present, the selective serotonin reuptake inhibitors (SSRIs) hold center stage, and fluoxetine hydrochloride (Prozac) is in the spotlight. The result of years of focused research and design, fluoxetine was rapidly accepted and prescribed to millions within a few months after its introduction in December 1987. As of 2005, long-term effects of SSRIs and potential elevated risks of suicide in young people taking SSRIs are under study.

Though much of the research and understanding of psychopharmacology comes from the field of medicine and psychiatry , there are, of course, other areas where psychotropic drugs have been used, ranging from illegal recreational use to the possibility of applying them as agents of "mind control." The Central Intelligence Agency (CIA) Crime and Narcotics Center monitors, reviews, and delivers information about international trafficking in illegal drugs and international organized crime to the nation's leaders and law enforcement agencies. Former Director of Central Intelligence William Webster created what became today's DCI Crime and Narcotics Center in April 1989. The center is staffed by people from the 13 agencies making up the US Intelligence Community, including the CIA, as well as from law enforcement agencies. The Crime and Narcotics Center's staff are responsible for estimating the amount of illegal drugs, mainly coca, opium poppy, and marijuana, produced around the world. They also assist law enforcement agencies to break up drug and organized crime groups and help law enforcement agencies detect and capture illegal drug shipments.

Psychotrophic drugs are potentially useful in the interrogation of suspects. One such drug is sodium pentothal, more commonly known as truth serum , which is used as a sedative and anesthetic during surgery. It depresses the central nervous system, slows the heart rate, and lowers blood pressure. Patients on whom the drug is used as an anesthetic are usually unconscious less than a minute after it enters the veins. Because of its effectiveness as a sedative, it was also one of the first of three drugs to be used by the U.S. prison system during executions. In milder doses, the drug affects people such that they often become more communicative and share their thoughts without hesitation. Despite its name, however, sodium pentothal will not make a person tell the truth against their will, but a recipient is only more likely to lose inhibitions and therefore, may be more likely to volunteer the truth.

see also Interrogation; Truth serum.

Psychoactive drugs

Medications used to treat mental illness and brain disorders.

Overview and use

The role of psychoactive drugs, also called psychotherapeutic agents or psychotropic drugs, in the treatment of mental illness is dependent on the disorder for which they are prescribed. In cases where mental illness is considered biological in nature, such as with a diagnosis of bipolar disorder or schizophrenia , pharmaceutical therapy with psychotherapeutic drugs is recommended as a primary method of treatment. In other cases, such as in personality disorder or dissociative disorder, psychoactive medications are usually considered a secondary, companion treatment (or adjunct) to a type of psychotherapy , such as cognitive-behavioral therapy. In these situations, medication is used to provide temporary symptom relief while the patient works on the issues leading to his illness with a therapist or other mental health professional.

Psychoactive drugs can be classified into seven major categories. These include:

• Antianxiety agents. Drugs used to treat anxiety disorders and symptoms. These include benzodiazepines such as alprazolam (Xanax), lorazepam (Ativan), diazepam (Valium), and chlordiazepoxide (Librium), and other medications including buspirone (Bu Spar) and paroxetine (Paxil).
• Antidepressants. Prescribed to treat major depressive disorder, dysthymic disorder, and bipolar disorder. Popular antidepressants include venlafaxine (Effexor), nefazodone (Serzone), bupropion (Wellbutrin), MAOI inhibitors such as phenelzine (Nardil) and tranylcypromine (Parnate); selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine (Prozac), paroxetine (Paxil), and sertraline (Zoloft); tricyclic antidepressants such as amitriptyline (Elavil), doxepin hydrochloride (Sinequan), desipramine (Norpramin), and perphenazine/amitriptyline combinations (Etrafon).
• Antimanic agents. This category includes medications used to treat mania associated with bipolar disorder (or manic-depressive disorder) such as divalproex sodium (Depakote) and lithium carbonate (Lithium, Eskalith, Lithobid, Tegrator).
• Antipanic agents. Prescribed to treat the panic symptoms that are a defining feature of many anxiety disorders. Medications include clonazepam (Klonopin), paroxetine (Paxil), alprazolam (Xanax), and sertraline (Zoloft).
• Antipsychotic agents. Also known as neuroleptic agents, these medications are used to manage psychosis related to schizophrenia, delusional disorder, and brief psychotic disorder. They include clozapine (Clozaril), haloperidol (Haldol), loxapine (Loxitane), molindone (Moban), thiothixene (Navane), risperidone (Risperdal), and olanzapine (Zyprexa); also includes phenothiazines such as prochlorperazine (Compazine), trifluoperazine hydrochloride (Stelazine), and chlorpromazine (Thorazine).
• Obsessive-compulsive disorder medications. Drugs used to treat OCD include fluvoxamine (Luvox), paroxetine (Paxil), fluoxetine (Prozac), and sertraline (Zoloft).
• Psychostimulants. Also known as central nervous system stimulants, these medications are used to treat attention deficit disorders (ADD and ADHD) and narcolepsy . They include methylphenidate hydrochloride (Methylin, Ritalin) and methaamphetamines (Desoxyn, Dexedrine, and Dextro Stat).

Side effects

There are a number of side-effects associated with psychotherapeutic agents. These can include, and are not limited to, dry mouth, drowsiness, disorientation, delirium , agitation, tremor, irregular heartbeat, headache, insomnia, gastrointestinal distress, nausea, menstrual irregularity, weight gain, weight loss, loss of sex drive, skin rashes, and sweating. Patients should inform their healthcare provider if they experience any of these side effects. In some cases, a dosage adjustment or change of prescription can alleviate any discomfort caused by them. Additional medications may also be prescribed to address severe side effects (e.g., anticholinergic medication may be prescribed for muscle spasms caused by antipsychotic medications).

Tardive dyskinesia, a condition characterized by involuntary movements of the mouth and other locations on the body, has been reported in some patients who take antipsychotic medication on a long-term basis. In some cases, the condition is permanent, although discontinuing or changing medication may halt or reverse it in some patients.

Agranulocytosis, a potentially serious illness in which the white blood cells that typically fight infection in the body are destroyed, is a possible side effect of clozapine, another antipsychotic. Patients taking this medication should undergo weekly blood tests to monitor their white blood cell counts.

Precautions

Psychotherapeutic agents can be contraindicated (not recommended for use) in patients with certain medical conditions. They may also interact with other prescription and over-the-counter medications, either magnifying or reducing the intended effects of one or both drugs. In some circumstances, they can trigger serious, even life-threatening, physical side effects. For this reason, individuals who are prescribed psychoactive medication should inform their mental healthcare provider and any other prescribing doctor of all medications they are taking, and of any medical conditions they have not yet disclosed.

Monoamine oxidase inhibitors (MAOIs) such as tranylcypromine (Parnate) and phenelzine (Nardil) block the action of monoamine oxidase (MAO), a chemical agent of the central nervous system . Patients who are prescribed MAOIs must eliminate foods high in tyra-mine (found in aged cheeses, red wines, and meats) from their diets to avoid potentially serious hypotensive side effects.

Patients taking Lithium, an antimanic medication, must carefully monitor their salt intake. Diarrhea, sweating, fever, change in diet, or anything else that lowers the level of sodium in their system can result in a toxic build up of Lithium, which can result in slurred speech, confusion, irregular heart beat, vomiting, blurred vision , and possibly death.

Certain psychoactive drugs are lethal in excessive doses, and therefore may not be a viable treatment option for patients at risk for suicide unless they can be dispensed in a controlled manner.

Many psychoactive drugs are contraindicated in pregnancy, particularly in the first trimester. Patients should check with their doctor about the risks associated with psychotherapeutic medications and possible treatment options when planning a pregnancy.

Paula Ford-Martin

Further Reading

Medical Economics Company. The Physicians Desk Reference (PDR). 54th edition. Montvale, NJ: Medical Economics Company, 2000.

Further Information

National Institute of Mental Health (NIMH). 6001 Executive Boulevard, Rm. 8184, MSC 9663, Bethesda, MD, USA. 20892-9663, fax: (301)443-4279, (301)443-4513. Email: [email protected]. http://www.nimh.nih.gov.

Psychotropic Drugs

PSYCHOTROPIC DRUG CLASSES

EFFICACIOUS USE OF PSYCHOTROPIC DRUGS

BIBLIOGRAPHY

Psychotropic drugs are substances prescribed to affect one’s behavior, emotions, or cognition. They can be categorized into the following drug classes: antipsychotics, antidepressants, anxiolytics, mood stabilizers, and stimulants. Psychotropic drugs are routinely used to treat various mental disorders, and their efficacy is determined by how well the drug decreases the presenting symptoms of a disorder, as well as the presence or absence of side effects.

PSYCHOTROPIC DRUG CLASSES

Antipsychotics are prescribed primarily to manage the symptoms associated with schizophrenia, autism, and other developmental disabilities. On occasion, they are used in combination with other drugs to treat depression and bipolar disorder. There are two classes of antipsychotic drugs: typical and atypical. The difference between these two groups lies in their mechanism of action. Typical antipsychotics are highly selective for dopamine receptors, specifically D2 receptors. Unfortunately, because of this selectivity, movement disorders (e.g., tardive dyskinesia) are a side effect of the typical antipsychotics. Given this undesirable side effect, atypical antipsychotics were developed. They differ from the typical antipsychotics in that they have a lower affinity for D2 receptors, and affect other neurotransmitter systems such as serotonin. Atypical antipsychotics have significantly fewer motor side effects; however, weight gain is an issue.

Antidepressants are used in the treatment of depression, post-traumatic stress disorder, anxiety, and obsessive compulsive disorder. There are three major classes of anti-depressants prescribed: monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs), and selective serotonin reuptake inhibitors (SSRIs). The best known of these is the SSRI. SSRIs exert their effect by blocking the reuptake of serotonin from the synapse into the presynaptic neuron, thus increasing its availability postsynaptically. Physiological side effects associated with SSRIs are usually minimal and transient, with the exception of sexual dysfunction. Increases in suicide ideation in adolescents treated with SSRIs have been reported, and thus SSRIs are not generally recommended for use with this population. Despite their popularity, SSRIs have not been found to be any more effective at treating depression than any other antidepressant.

Anxiolytics are prescribed to treat anxiety and sleep disorders. There are two classes of anxiolytics, benzodiazepines and non-benzodiazepines. Benzodiazepines exert their effects by increasing the efficiency of gammaaminobutyric acid (GABA), an inhibiting neurotransmitter. These drugs are fast-acting, and side effects include the potential for physiological addiction. Non-benzodiazepines include buspirone, which exerts its effect via activity at serotonin receptors. The potential for abuse with non-benzodiazepines is less than with benzodiazepines, but they also appear to be less effective at treating anxiety disorders than benzodiazepines.

Although lithium is the only drug used specifically for the treatment of bipolar disorder, anticonvulsants such as lamotrigine also have been demonstrated to have mood-stabilizing properties. At the present time, the neuropharmacology of these drugs in the treatment of mood disorders is not understood, and both lithium and certain anticonvulsants require routine blood monitoring to guard against toxicity.

Finally, stimulants are prescribed to treat attention disorders such as attention deficit/hyperactivity disorder (ADHD). These drugs operate by increasing the availability of dopamine, epinephrine, norepinephrine, and/or serotonin. Side effects associated with stimulants are decreased appetite and difficulty sleeping.

EFFICACIOUS USE OF PSYCHOTROPIC DRUGS

Prior to the advent of psychotropic drugs in the late 1940s, treatment of psychiatric disorders included admittance to asylums, physical restraints, and psychoanalysis. Consistent and effective results of treatment were often elusive. Advances in technology and the convergence between the fields of psychiatry, neurology, genetics, and neuroscience have made it possible to evaluate the therapeutic effects of psychotropic drug use, and to make predictions about who will respond well to their use. The application of neuroimaging techniques such as functional magnetic resonance imaging (fMRI) to drug evaluation allows assessment of changes in cerebral blood flow, volume, and oxygenation as a function of psychotropic drug use that may provide an indication of the efficaciousness of psychotropic treatment in disorders such as schizophrenia and depression (Tracey and Wise 2001). Psychopharmacogenomics is another approach that attempts to predict efficacious drug treatment (Malhotra, Murphy and Kennedy 2004). The goal is to identify polymorphisms or mutations of genes involved in receptor function, pharmacokinetics, and pharmacodynamics, to determine who is at an increased risk for experiencing side effects of psychotropic drugs. With each of these technological advances, the aim is to improve prescribing practices and provide individualized, effective treatment while ensuring quality of life.

SEE ALSO Adolescent Psychology; Cognition; Emotion; Genomics; Mental Health; Mental Illness; Neuroscience; Psychoanalytic Theory; Psychology; Psychoneuroendocrinology; Psychoneuroimmunology; Psychotherapy; Suicide

BIBLIOGRAPHY

Malhotra, Anil K., Greer M. Murphy, and James L. Kennedy. 2004. Pharmacogenetics of Psychotropic Drug Response. American Journal of Psychiatry 161 (5): 780–796.

Stahl, Stephen M. 2000. Essential Psychopharmacology: Neuroscientific Basis and Practical Applications. 2nd ed. Cambridge, U.K.: Cambridge University Press.

Tracey, Irene, and Richard G. Wise. 2001. Pharmacological fMRI: A New Tool for Drug Development in Humans. Journal of Pharmacy Practice 14 (5): 368–375.

Maria G. Valdovinos

Psychoactive Drugs

Psychoactive drugs are a class of chemical substances that act on the central nervous system and can alter behavior and cognition . All psychoactive drugs are highly fat-soluble and thus cross the blood-brain barrier readily. Psychoactive drugs alter synaptic transmission by altering neuro-transmitter amounts and availability or by affecting receptor activity. In addition to the drug's primary effects on behaviors such as arousal, thought processes, mood, perception, and consciousness, psychoactive drugs can produce a variety of nonbehavioral effects that may more directly affect health and, in some instances, can lead to death.

Although there are several different classification schemes for psychoactive drugs (pharmacological, legal, medical), the most common organization is based on their effect on behavior and cognition. According to this scheme, psychoactive drugs can be classified into four broad categories: (1) sedatives and hypnotics, (2) stimulants, (3) opiates, and (4) hallucinogens and psychedelics.

Sedatives and Hypnotics

Sedatives and hypnotics depress or inhibit brain activity and produce drowsiness, sedation, or sleep; relieve anxiety; and lower inhibition. Although the depressant compounds do not share a common neural mechanism of action, most of them either decrease the metabolic activity in the brain or increase the transmission of the principal inhibitory neurotransmitter of the brain, gamma-aminobutyric acid (GABA).

All sedatives have the potential for addiction and dependency. Common depressants include barbiturates, such as Seconal; benzodiazepines, such as Xanax and Valium (commonly called minor tranquilizers); nonbarbiturate sedatives, such as methaqualone; newer nonbenzodiazepines, such as buspirone, antihistamines, and anesthetics; and alcohol. In low doses, alcohol can act as a stimulant; however, with increased dosage alcohol's main effect is depressive.

Stimulants

Stimulants produce behavioral arousal. As with the sedatives and hypnotics, there are a variety of substances, each with a different neural mechanism of action. Examples of stimulants are amphetamine, cocaine, antidepressants, caffeine (the most widely used psychoactive drug in the world), nicotine or tobacco, appetite suppressants, and a variety of exotic plant products. Stimulants vary in strength, legal status, and the manner in which they are taken; however, all stimulants have addictive potential.

Opiates

All drugs in the opiate class act on opiate receptors in the brain. They mediate relief from pain and produce feelings of euphoria. Opiates, which are referred to as narcotics by scientists and medical practitioners, are highly addictive and can either be natural, semisynthetic, or synthetic. Natural opiates such as opium are derived from the opium poppy. The active ingredients of opium are morphine and codeine. The most common semisynthetic opiate is heroin, which is five to ten times more potent than morphine. Examples of synthetic opiates include methadone and the prescription pain medication Demerol.

Hallucinogens and Psychedelics

Hallucinogens and psychedelics do not share a common mechanism of action, but all induce hallucinations . These drugs can either be natural such as mescaline, which is derived from the peyote cactus, or synthetic such as lysergic acid diethylamide (LSD), but they are typically classified pharmacologically according to the affected neurotransmitter system.

Cholinergic psychodelics (drugs altering acetylcholine transmission) include physostigmine, scopolamine, and atropine. Drugs that alter norepinephrine transmission include mescaline and ecstasy . Drugs that alter serotonin transmission include LSD and psilocin. Other drugs in this category include the psychedelic anesthetics phencyclidine (PCP) and ketamine.

Marijuana, which is derived from the hemp plant Cannabis sativa, is often classified as a psychedelic substance, although only in very high doses does it produce sensory distortions. Marijuana's most common behavioral symptom is sedation. Unlike other drug classes, and with the exception of the cholinergic psychedelics, hallucinogenic and psychedelic drugs are generally nonlethal even when taken in large doses.

Other Drugs that Affect the Central Nervous System

Additionally, there are a number of other drugs that affect central nervous system functioning. These compounds are used to treat a variety of psychological and neurological disorders and include antidepressants, antipsychotic medication, and drugs for epilepsy, Parkinson's disease, the dementias (such as Alzheimer Disease), and spasticity .

Categorizing Drugs into Five Schedules

A different approach to the classification of psychoactive drugs is taken by the legal system, which considers all illegal drugs or controlled substances "narcotics." According to the Comprehensive Drug Abuse Prevention and Control Act of 1970, drugs are categorized into five schedules according to the perceived risk of dependency.

Schedule I drugs, such as heroin, marijuana, and most psychedelics, have a high risk of dependency and no widely accepted medical use. These drugs are forbidden and cannot be obtained even by prescription (although marijuana is available in some states). Schedule II drugs, such as morphine, codeine, amphetamines, and certain barbiturates, have a high risk of dependency but are accepted by the medical community for treatment. Schedule III drugs have a risk of moderate physical dependency or high risk of psychological dependency and include preparations with limited opiates (morphine) and barbiturates not in Schedule II.

Schedule IV drugs, which include the benzodiazepines, have a slight risk of mild physical or psychological dependency. Schedule V drugs have less risk of mild physical or psychological dependency. Finally, alcohol and tobacco are not classified under this law. They fall under the jurisdiction of the Bureau of Alcohol, Tobacco and Firearms (ATF), which is a division of the U.S. Department of the Treasury.

see also Alcohol and Health; Drug Testing; Nervous Systems; Neuron; Synaptic Transmission

Arne Dietrich

Bibliography

Goodman, Louis S., et al., eds. Goodman & Gilman's The Pharmacological Basis of Therapeutics, 9th ed. Elmsford, NY: McGraw-Hill, 2000.

Ross, R. T. How to Examine the Nervous System, 2nd ed. Stamford, CT: Appleton & Lange, 1999.

Schatzberg, Alan F., and Charles B. Nemeroff, eds. Textbook of Pharmacology, 2nd ed. Washington, DC: American Psychiatric Press, 1995.