Chemistry for Liberal Studies - Forensic Academy / Dr. Stephanie R. Dillon

Drug Structure and Function

All of the drugs that are commonly abused fall into one of the seven general categories: Narcotics, Stimulants, Depressants, Hallucinogens, Cannabis, Steroids and Inhalants. The Top 10 Drugs Abused:

We will now look more carefully at each type of drug and how the chemistry of that drug works with the biochemistry of our bodies to create addiction.

Narcotics

Narcotics are drugs that are naturally derived from opium.

Opium is derived from the juice of the poppy plant. Narcotics are often referred to as Opiates for this reason.

The most common opiates (narcotics) are:

You should note that only two of the narcotics (Heroin and Cocaine) on this list are considered illegal. Opiates are all structurally similar.

Because their structures are similar they will react with similar receptors in the brain and cause similar chemical reactions. The differences in the structures of these compounds lead to their differing levels of biological activity.


Dopamine

Pain & Opiates
denny both (YouTube)

Narcotics are used legally to counteract pain by producing a feeling of euphoria by stimulating the pleasure centers (dopamine receptors) in the brain. If not used properly, the euphoria is followed by drowsiness, nausea, and vomiting. Users also may experience constricted pupils, watery eyes, and itching. An overdose may produce slow and shallow breathing, clammy skin, convulsions, coma, and possibly death.

Stimulants

Stimulants increase alertness, attention, and energy, as well as elevate blood pressure, heart rate, and respiration. Stimulants historically were used to treat asthma and other respiratory problems, obesity, neurological disorders, and a variety of other ailments.

As you can see from the inclusion of cocaine in the list above, stimulants can be narcotic as well as other types of chemicals.

But as with the opiates, most of the stimulants share a similar chemical structure:

Stimulants' Mechanisms of Action

On a short-term basis, stimulants exert their effects by disrupting or modifying the normal communication that occurs among brain neurons and brain circuits. Cocaine has been shown to specifically disrupt the dopamine neurotransmitter system. The use of cocaine increases the amount of available dopamine in the brain, which leads to mood elevation (e.g., feelings of elation or euphoria) and increased motor activity. With cocaine, the effects are short-lived; with methamphetamines the duration of the high is much longer. As the stimulant level in the brain decreases, the dopamine levels subside to normal, and the pleasurable feelings dwindle away.

The chronic use of stimulants affect dopamine pathway neurons located in the limbic reward system structures. (Even too much nasal spray which contain epinephrine or caffeine could be damaging). These effects may be the basis for the addiction to stimulants.

Depressants

Depressants are drugs that work on the central nervous system (CNS) to slow normal brain function. In high doses, some CNS depressants can be used as general anesthetics. Tranquilizers and sedatives are examples of CNS depressants.

CNS depressants can be divided into two groups, based on their chemistry and pharmacology:

There are many CNS depressants, and most act on the brain similarly. They affect the neurotransmitter gamma-aminobutyric acid (GABA). GABA works by decreasing brain activity. Although different classes of CNS depressants work in unique ways, ultimately it is their ability to increase GABA activity that produces a drowsy or calming effect. Despite these beneficial effects for people suffering from anxiety or sleep disorders, barbiturates and benzodiazepines can be addictive.

Again, looking at the list above you see that some opiates fall into the category of depressants and that alcohol is also a depressant. The grouping of these chemicals into the depressant group is in reference to their effect on GABA more than their structural similarities. Although the barbiturate family of depressants does share similarity of structure:

Alcohol on the Brain - Acute effects
Sam Scopelliti (YouTube)

Alcohol, specifically ethanol which is the alcohol that is safe to consume, has a very different structure from those above.


Ethanol

But it is still classified as a depressant because of its effect on the GABA receptor. If you think about it, you can correlate some facts you are already aware of with the new material you have been learning about drugs in this lecture. Taking alcohol as the example, you are probably already aware that over time you build up a resistance to the alcohol you intake. Your tolerance increases as you continue to drink alcohol over time and it takes more alcohol each time to reach the same "buzz". If you have ever consumed alcohol, you have also probably suffered the symptoms of withdrawal (the hangover). You now know from a chemical stand point not only how but why these symptoms take place.

Let's talk next about something you have hopefully never experienced: Hallucinations.

Hallucinogens

Hallucinogenic compounds are found in some plants and mushrooms (or their extracts). These compounds have historically been used in religious rituals; the hallucinations that they create supposedly having predictive qualities. Structurally almost all hallucinogens contain nitrogen and are classified as alkaloids. Many hallucinogens have chemical structures similar to those of natural neurotransmitters (e.g., acetylcholine-, serotonin-, or catecholamine-like chemicals that transmit signals through nerve cells from the brain to the body).

The exact mechanism by which hallucinogens exert their effects is not fully understood. The current thinking is that they temporarily interfere with either neurotransmitter action pathways or bind neurotransmitter receptor sites preventing normal function.

There are four common types of hallucinogens:

LSD (d-lysergic acid diethylamide). F in the picture above. LSD is one of the most potent mood-changing chemicals. The hallucinations it causes often last for up to 12 hours. LSD can be distributed as pills, liquid or even as a coating on paper

.

How LSD effects the Brain
tokensmith (YouTube)

 

Peyote (Mescaline) A in the picture above is a small, spineless cactus in which the principal active ingredient is mescaline. This plant has been used by Native Americans as a part of religious ceremonies for centuries. The peyote is generally chewed or drank as a tea.

Psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine) D in the picture above is obtained from certain types of mushrooms that are indigenous to tropical and subtropical regions of South America, Mexico, and the United States. These mushrooms typically contain less than 0.5 percent psilocybin plus trace amounts of psilocin, another hallucinogenic substance. The mushrooms can be eaten or stewed in tea for consumption. The effects last about 6 hours.

PCP (phencyclidine) Shown below was originally developed in the 1950s as an anesthetic.

PCP is a white crystalline powder that is readily soluble in water or alcohol. It has a distinctive bitter chemical taste. PCP can be mixed easily with dyes and is often sold on the illicit drug market in a variety of tablet, capsule, and colored powder forms that are normally snorted, smoked, or orally ingested. Depending upon how much and by what route PCP is taken, its effects can last approximately 4�6 hours.

Hallucinogen Effects

Under the influence of hallucinogens, people see images, hear sounds, and feel sensations that seem real but are not. Some hallucinogens also produce rapid, intense emotional swings.

LSD, peyote, and psilocybin cause their effects by initially disrupting the interaction of nerve cells and the neurotransmitter serotonin. Serotonin is the neurotransmitter that controls memory, appetite, sex drive and sleep.

On the other hand, PCP acts mainly through a type of glutamate receptor in the brain that is important for the perception of pain, responses to the environment, and learning and memory.

Individuals on have been know to break limbs without knowing it due to PCP's numbing effects. Abusers are considered very dangerous because without the ability to feel pain they can continue to fight and be violent without feeling the consequence even after being shot, tazed or pepper sprayed.

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Cannabis

THC, or tetrahydrocannabinol, is the chemical responsible for most of marijuana's psychological effects. THC changes behavior by binding � fitting together like a lock and key � to receptors on nerve cells, which then respond with a change in activity.


THC, or tetrahydrocannabinol

Cannabinoid receptors are concentrated in certain areas of the brain associated with thinking, memory, pleasure, coordination and time perception. There are also cannabinoid receptors on nerves in other parts of the body. THC relieves pain, but it doesn't bind to the same receptors in the brain as opioids such as heroin, morphine and other drugs derived from the poppy plant.

THC stimulates cells in the brain to release dopamine, creating euphoria. It also interferes with how information is processed in the hippocampus, which is part of the brain responsible for forming new memories. THC can induce hallucinations, change thinking and cause delusions.

Steroids

Unlike many of the other drugs on this list, Steroids are not abused for the high they produce but rather for the physiological changes they can manifest. There are two types of steroids present within the body: Corticosteroids and Androgenic/Anabolic Steroids.

Corticosteroids, which are hormones that regulate sodium concentration, inflammation and fat levels in the body. The two main corticosteroids are aldosterone and cortisol. Also unlike many of the previous drugs the steroids have many medical applications. Corticosteriods are used to treat diseases like asthma, rheumatoid arthritis, inflammatory bowel disease, and systemic lupus erythematosus in which inflammation is part of the disease process.

Androgenic/Anabolic steroids are hormones that regulate the manufacture of testosterone in the sex organs. The main hormone is testosterone:


Testosterone

The androgenic part of testosterone is involved in developing the male sex characteristics, while the anabolic part is involved in increasing the amount of body tissue by increasing protein production.

Androgenic/Anabolic steroids are prescribed to individuals whose own hormone levels are insufficient to produce enough muscle mass or male characteristics. Unfortunately, because one of the main effects of this group of steroids is to make higher muscle mass it is often abused by those in the field of sports. When the steroid is not needed to supplement a low testosterone, anabolic steroids will cause weight gain primarily due to an increase in muscle mass.

It is easy to spot those that are abusing steroids, although the symptoms are very different from those of other drugs abusers.

Steroid abuse manifests as rapid weight gain, mood swings that can be violent in nature and lots of ACNE:

A few common examples of anabolic steroids include:

Steroids are taken both as pills and also as injections. For the best results, and also to avoid detection, they are normally taken in cycles since the results are not immediate. The body has to have time to put the drugs to use.

The abuse of steroids has become high profile in the past few decades due to the high profile athletes that have been found guilty of the crime:

If you noted that all of these athletes at one time were thought to be tops in their fields you can understand the draw of steroid abuse.

You might also notice that there is only one woman on the list, Marion Jones. This is because it is much rarer for women to abuse steroids than men due to the side effects: facial hair, loss of breast tissue and growth of the clitoris. While men on steroids become more masculine women do too.


A. J. Fowe

Inhalants

The Dangers of Inhalants
rosaryfilms (YouTube)

The last category of drugs we will cover may not really seem like a drug at all. This is because the products in this drug category, spray paints, markers, glues, and cleaning fluids etc. are just common household chemicals. But these chemicals all contain volatile substances that have psychoactive (mind-altering) properties when inhaled. The abuse of these products is normally perpetrated by young children and teenagers.

Chemically inhalants all have similar chemical contents:

Aerosols Harmful Chemical
Paint Sprays butane; propane (U.S.); fluorocarbon; hydrocarbons; toluene
Hair Sprays butane; propane (U.S.); fluorocarbon
Deodorants, Air Freshener butane; propane (U. S.); fluorocarbon
Analgesic Spray fluorocarbon
Asthma Spray fluorocarbon
Solvents Harmful Chemical
Polish remover acetone
Paint remover toluene; methylene chloride; methanol
Paint thinners toluene; methylene chloride; methanol
Correction Fluid toluene; methylene chloride; methanol
Fuel Gas butane
Lighter butane; isopropane
Fire extinguisher bromochlorodifluoromethane

You should notice that most of the contents in the inhalant "drugs" are hydrocarbons (molecules made up of predominantly hydrogen and carbon) and halogens (F, Cl, Br).


Toluene

Most abused inhalants depress the central nervous system much like alcohol. The effects of an inhalant on an abuser is dizziness, slurred speech, light-headedness and even hallucinations. Unlike other psychotropic drugs, inhalants are not known to cause severe addiction although in rare cases it does occur. This may be because repeated use of the inhalant causes sleepiness and headaches not euphoria.

The side effects of inhalant use can be severe. Because repeated inhalation of the drug compromises the normal breathing pathways and oxygen supply to the brain, inhalants can even be lethal. Sniffing highly concentrated amounts of the chemicals in solvents or aerosol sprays can directly cause heart failure within minutes. This syndrome, known as "sudden sniffing death," can result from a single session of inhalant use by an otherwise healthy young person. High concentrations of inhalants may also cause death from suffocation, especially when inhaled from a paper or plastic bag or in a closed area.

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