INTRODUCTION

A psychoactive drug or psychotropic substance is a chemical substance that

acts primarily upon the central nervous system where it alters brain function,

resulting in temporary changes in perception, mood, consciousness and

behavior. These drugs may be used recreationally to purposefully alter one's

consciousness (such as coffee, alcohol or cannabis), as entheogens for

spiritual purposes (such as the mescaline-containing peyote cactus or

psilocybin-containing mushrooms), and also as medication (such as the use of

narcotics in controlling pain, stimulants to treat narcolepsy and attention

disorders, as well as anti-depressants and anti-psychotics for treating

neurological and psychiatric illnesses). Many of these substances (especially

the stimulants and depressants) can be habit-forming, causing chemical

dependency and may lead to substance abuse.

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 ofbipolar

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 healthprofessional.

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).

DRUG ABUSE and DRUG ADDICTION

Drug abuse is a disorder that is characterized by a destructive pattern of using a

substance that leads to significant problems or distress.

Drug addiction is a disease that is characterized by a estrucive pattern of drug

abuse that leads to significant problems involving tolerance to or withdrawal from

the substance, as well as other problems use of the substance can cause for th

sufferer.

Drug abuse and addiction are unfortunately quite common, affecting 7% and

more than 2% of people at some point in their lives respectively.

While the physical and psychological fffects of drug abuse and addiction then to

vary based on the particular substance involved, the general effects of abuse or

addiction to any drug can be devastating.

Similar to other chronic, relapsing diseases, such as diabetes, asthma, or heart

disease, drug addiction can be managed successfully. And as with other chronic

diseases, it is not uncommon for a person to relapse and begin abusing drugs

again. Relapse, however, does not signal treatment failure—rather, it indicates

that treatment should be reinstated or adjusted or that an alternative treatment is

needed to help the individual regain control and recover.

As a person continues to abuse drugs, the brain adapts to the overwhelming

surges in dopamine by producing less dopamine or by reducing the number of

dopamine receptors in the reward circuit. The result is a lessening of dopamine’s

impact on the reward circuit, which reduces the abuser’s ability to enjoy not only

the drugs but also other events in life that previously brought pleasure. This

decrease compels the addicted person to keep abusing drugs in an attempt to

bring the dopamine function back to normal, but now larger amounts of the drug

are required to achieve the same dopamine high—an effect known as tolerance.

Long-term abuse causes changes in other brain chemical systems and circuits as

well. Glutamate is a neurotransmitter that influences the reward circuit and the

ability to learn. When the optimal concentration of glutamate is altered by drug

abuse, the brain attempts to compensate, which can impair cognitive function.

Brain imaging studies of drug-addicted individuals show changes in areas of the

brain that are critical to judgment, decision making, learning and memory, and

behavior control. Together, these changes can drive an abuser to seek out and

take drugs compulsively despite adverse, even devastating consequences—that is

the nature of addiction.

Classifications of Psychoactive Drugs

Psychoactive drugs are chemical substances that affect the brain functioning, causing changes in

behavior, mood and consciousness. While these drugs can be used therapeutically to treat both

physical and psychological disorders, they are also used recreationally to alter mood, perceptions

and consciousness. The way drugs are grouped together will vary depending upon who is doing

the categorisation and the purpose for which it is intended. The laws surrounding drug use

serve two purposes. On the one hand they are intended to directly restrict access to particular

substances. Restrictions on the sale of alcohol and penalties for the sale and possession of illicit

drugs are designed to reduce the availability of, and therefore prevent consumption of,

substances which may have detrimental effects. From a psychological perspective they also

contribute to social norms surrounding those substances. The fact that a substance is illegal

will discourage some individuals from using it, even if they could actually obtain it. Of course,

other individuals might be attracted to that substance for the same reason.

In addition to the classification scheme embodied in the law, such drugs can also be

categorised based on their effects. Here too, the number of categories identified will vary.

Categorisation may be on the basis of drugs' broad effects on behaviour, their chemical

structure or the brain neurotransmitter systems they primarily affect. Different approaches will

give rise to slightly different classification schemes. Drugs which have similar chemical

structures may have different behavioural effects, while drugs which have similar effects may

have very different chemical structures. I am going to describe the main classes of

psychoactive drugs that are used for non-medical purposes below. By now I hope you realise

that this division is somewhat arbitrary. Any of the psychopharmacology texts on the module

reading list would tell you more about the topics discussed. The textbooks by Parrot et al.

(2004) or Mckim (2003) are particularly recommended. The next section of the course will say

more about the ways in which drugs are able to affect behaviour and how drug's effects may

be influenced by the route by which they are administered.

Here are the classifications of psychoactive drugs:

Stimulants Depressants Opiates Hallucinogens Cannabis

Stimulants

Stimulants are a class of psychoactive drug that increase activity in thebrain. These drugs can temporarily elevate alertness, mood, and awareness. While some stimulant drugs are legal and widely used, all can be addicting. Stimulants share many commonalities, but each has unique properties and mechanisms of action. These drugs are sometimes called as “uppers”.

The most commonly used street drugs that fall into this category are cocaine and amphetamines.

Prescription stimulants come in tablets or capsules. When abused, they are swallowed, injected in liquid form or crushed and snorted.

SHORT-TERM EFFECTS

The short-term effects of stimulants include exhaustion, apathy and depression—the “down” that follows the “up.” It is this immediate and lasting exhaustion that quickly leads the stimulant user to want the drug again. Soon he is not trying to get “high,” he is only trying to get “well”—to feel any energy at all.

LONG-TERM EFFECTS

Stimulants can be addictive. Repeated high doses of some stimulants over a short period can lead to feelings of hostility or paranoia. Such doses may also result in dangerously high body temperatures and an irregular heartbeat.

 

Drugs that are classed as stimulants include:

Caffeine

Nicotine

Cocaine

Amphetamines

Prescription drugs

Caffeine

Caffeine is naturally produced by

several plants, including coffee beans,

guarana, yerba maté, cacao beans,

and tea. For the plants, caffeine acts

as a natural pesticide. caffeine is also

an addictive stimulant. In humans, it

stimulates the central nervous system,

heart rate, and respiration, has psychotropic (mood altering) properties, and

acts as a mild diuretic.

A normal dose of caffeine is generally considered to be 100 mg, which is

roughly the amount found in a cup of coffee. However, more than half of all

American adults consume more than 300 mg of caffeine every day, which

makes it America's most popular drug. Caffeine is generally consumed in

coffee, cola, chocolate, and tea, although it is also available over-the-counter

as a stimulant.

Caffeine is believed to work by blocking adenosine receptors in the brain and

other organs. This reduces the ability of adenosine to bind to the receptors,

which would slow down cellular activity. The stimulated nerve cells release

the hormone epinephrine (adrenaline), which increases heart rate, blood

pressure, and blood flow to muscles, decreases blood flow to the skin and

organs, and causes the liver to release glucose. Caffeine also increases levels

of the neurotransmitter dopamine.

Caffeine is quickly and completely removed from the brain. Its effects are

short-lived and it tends not to negatively affect concentration or higher brain

functions. However, continued exposure to caffeine leads to developing a

tolerance to it. Tolerance causes the body to become sensitized to to

adenosine, so withdrawal causes blood pressure to drop, which can result in a

headache and other symptoms. Too much caffeine can result in caffeine

intoxication, which is characterized by nervousness, excitement, increased

urination, insomnia, flushed face, cold hands/feet, intestinal complaints, and

sometimes hallucinations. Some people experience the symptoms of caffeine

intoxication after ingesting as little as 250 mg per day. The lethal ingested

dose, for an adult person, is estimated to be 13-19 grams. While generally

considered safe for people, caffeine can be very toxic to household pets, such

as dogs, horses, or parrots. Caffeine intake has been demonstrated to reduce

the risk of type II diabetes mellitus. In addition to use as a stimulant and

flavoring agent, caffeine is included in many over-the-counter headache

remedies.

Nicotine

Nicotine is a chemical compound that is present in tobacco. When tobacco is

smoked, nicotine is absorbed through the

wall lining of the small air sacs in the lungs.

When sniffed or chewed, it is absorbed

through the mucous membranes of the nose

or mouth. Nicotine can also be absorbed

through the skin. Regardless of how nicotine

is absorbed, it enters the bloodstream where it circulates throughout the body

and travels to the brain where it crosses the blood-brain barrier. Once in the

brain, it binds to and activates receptors called the cholinergic receptors.

Effects

These cholinergic receptors are present in the brain as well as in other areas

such as the muscles, heart, adrenal glands and other vital organs. Normally,

these receptors are activated by the neurotransmitter acetylcholine which is

produced at nerve endings in the brain and in the nerves of the

peripheral nervous system.

The actions of acetylcholine help to maintain healthy respiration, heart

function, muscle movement and cognitive functions such as memory.

Since nicotine has a similar structure to acetylcholine, it can activate the

cholinergic receptors. However, unlike acetylcholine, nicotine enters the brain

and disrupts its normal functioning. Regular smoking leads to a change in the

number of cholinergic receptors and to changes in their sensitivity to nicotine.

This can lead to the development of nicotine tolerance.

Once this happens, the affected person needs to use nicotine regularly to

maintain normal brain function. If the level of nicotine falls, the smoker may

experience unpleasant withdrawal symptoms that lead to them "topping up"

their nicotine levels by smoking again. Because of its highly addictive

properties, smoking is considered by the American Heart Association to be

one of the hardest addictions to break.

Coccaine

 Cocaine is an illegal psychoactive drug made from the leaves of the

coca tree. During the late 1800s, psychoanalystSigmund Freud advocated the

use of cocaine as a therapeutic treatment for psychological disorders, but

later realized the addictive properties of the drug. During the early 1900s,

cocaine was legal in the U.S. and could be found in many over-the-counter

medications.

Cocaine is rapidly absorbed from any administration point, including being

snorted, inhaled, injected, or taken orally. The drug reaches the brain quickly

and is then distributed to other tissues throughout the body. Cocaine is rapidly

metabolized by enzymes in the liver and plasma in approximately 30 to 60

minutes, but can be detected in urine tests for up to 12 hours after

administration.

Amphetamines

Amphetamines, sometimes referred to as "uppers," are a group of

psychoactive drugs that affect the central nervous system

and autonomic nervous system. Some of the effects of using these drugs

include tremors, vasoconstriction, restlessness, tachycardia, insomnia,

agitation, and loss of appetite.

Amphetamines were once widely used in obesity and weight loss

treatments, but their addictive properties have caused them to be rarely

used today. Today, methamphetamine, also known as meth, is one of the

most commonly used illegal amphetamines. Meth is extremely addictive

and destroys tissues in the brain, which can lead to brain damage.

Prescribed Stimulants

Prescription stimulants are used to treat some physical and

psychological disorders, including attention-deficit hyperactivity

disorder (ADHD) and narcolepsy. Common names of prescription

stimulants include Ritalin, Adderall, and Dexedrine. Prescription

stimulants work by enhancing the effects of dopamine and

norepinephrine, and can lead to increased blood pressure, respiratory

function and euphoria.

Depressants

Depressants are drugs that inhibit the function of thecentral nervous system (CNS) and are among the most widely used drugs in the world. These drugs operate by affecting  neurons in the CNS, which leads to symptoms such as drowsiness, relaxation, decreased inhibition, anesthesia, sleep, coma, and even death. All depressants also have the potential to be addictive.While CNS depressants all share an ability to reduce activity in the central nervous system and lower levels of awareness in the brain, there are important differences among substances within this drug class. Some are safer than others, while others have more potential for use for medicinal purposes.

Depressants are generally used to induce sleep or relaxation. While depressants are typically associated with sleep or relaxation, they act upon the body by "depressing" or inhibiting the central nervous system's normal activity. Since some parts of the brain function to control outward behavior, the use of depressants may lead to an inhibition of that control. Thus, behavior not occurring under normal circumstances might occur with depressant use. A stereotypical example of this concept is an individual, after consuming too much of the depressant alcohol at a party, loses his ability to control his behavior, and decides to dance with a lampshade on his head. Some typical physiological responses occurring with depressant use include reduced tension, anxiety relief, slurred speech, staggered gait, and relaxed muscles. Excessive use may lead to slowed, shallow breathing; clammy skin; weak, rapid pulse; coma and death. Alcohol is one of the better-known, legal depressants readily available today.

Drugs that are classed as depressants include: Ethyl alcohol

Barbiturates

Benzodiazepines

Ethyl Alcohol

Alcohol, also known as ethyl alcohol, is the second most widely

used psychoactive drugs in the world (caffeine is number one).

While alcohol is a legal drug, it also has a high potential for abuse.

One survey conducted by the Substance Abuse and Mental Health

Services Administration found that nearly 70 million over the age

of 12 reported participating in binge drinking or heavy drinking

(2002). Alcohol use and abuse also has high social costs. According

to the American Psychiatric Association, approximately 50 percent

of all assaults, homicides, and highway deaths involve alcohol

(2000).

Barbiturates

Barbiturates are a class of drugs derived

from barbituric acid that act as

depressants to the central nervous

system. These drugs are frequently used

for medical reasons as sedatives or

anesthetics.

Effects of Barbiturates

The pharmacological actions of barbiturates include depressing nerve activity in the cardiac, smooth and skeletal muscles. These drugs also affect the CNS in several different ways and can produce effects ranging from mild sedation to a coma depending upon the dosage. Low doses of barbiturates can lower anxiety levels and relieve tension, while higher doses can decrease the heart rate and blood pressure.

Barbiturates do have some severe drawbacks, including:

Potentially dangerous interactions with other drugs.

Lack of safety and selectivity.

A tendency to create dependence, tolerance, abuse and withdrawal.

Examples of Barbiturates

Allobarbital

Amobarbital

Barbital

Pentobarbital

Phenobarbital

Secobarbital

Benzodiazepines

Benzodiazepines are a class of psychoactive drugs that act as central nervous system depressants. Because death from from benzodiazepine overdose is rare, these are the CNS depressants most prescribed and have largely replacedbarbiturates for use as hypnotics, anesthetics and sedatives.

Effects of Benzodiazepines

Benzodiazepines have been used for a wide variety of purposes, including in the treatment of back pain, anxiety and insomnia. The drugs work by selectively affecting neurons that have receptors for the neurotransmitter gamma aminobutyric acid (GABA). When benzodiazepines are introduced, the inhibiting effects of GABA are magnified. As a result, people taking these drugs experience altered mood, relaxed muscles and drowsiness.In some instances, benzodiazepines can have what are known as paradoxical effects. Unusual symptoms such as nervousness, anxiety, sweating, tension, restlessness and nightmares can occur.

Examples of Benzodiazepines

Alprazolam (Xanax)

Clonazepam (Klonopin)

Deazepam (Valium)

Lorazepam (Ativan)

Triazolam (Halcion)