Drugs of Abuse

Objectives:

• Be able to define the following terms:

▫ Pharmacology

▫ Drug

▫ Stimulant

▫ Depressant

▫ Hallucinogen

• Drugs of abuse:

▫ Pharmacology

▫ Physiological effects

▫ Toxicity

Important definitions:

• Pharmacology:

▫ The scientific study of the effect of drugs on biological system

• Drug:

▫ Any chemical substance, other than food, that alters the mental state or biological function of living organisms

▫ Medically, a drug is any chemical substance used in the treatment, cure, prevention, or diagnosis of disease.

Types of Drugs• Stimulants:

▫ Substances that stimulate or speed up the functions of the nervous system

Enhances alertness, wakefulness, and locomotion

• Depressants:

▫ Substances that depress or decrease the functions of the nervous system

Enhances relaxation and calmness

• Hallucinogens:

▫ Substances that cause changes in perception, thought, emotion, and consciousness

How Drugs Affect the Body

• The effect produced by a drug is an alteration of a natural physiological function or process.

• Drugs bind to a target to either activate, partially activate, or inactivate it.

• Most common drug targets include

▫ Transporters

▫ Ion Channels

▫ Receptors

▫ Enzymes

How Drugs Affect the Body

• Most common drug targets include

Enzyme: Biological molecule that cause a specific biochemical reaction

Drug Actions at the Synapse

Drugs of Abuse

http://learn.genetics.utah.edu/content/addiction/mouse/

Drugs of Abuse

• Heroin

• Alcohol

• Cocaine

• Methamphetamine

• Ecstasy (MDMA)

• LSD

• Marijuana

• Nicotine

• Caffeine

Heroin

• Synthetic opioid drug that is highly addictive. It is processed from morphine, a naturally occurring substance in poppy plants

Heroin Pharmacology

• Main site of action:

▫ Opiate receptors in the

Brain and spinal cord

Thalamus

Hypothalamus

Nucleus accumbens

Medulla

Sensory nerves in peripheral nervous system (PNS)

• Decreases the release of neurotransmitters into the synaptic cleft

Heroin Pharmacology

• Binds to opiate receptors in

▫ Reward/pleasure centers of the brain (image above) to induce eupohoria

▫ Brain, spinal cord, and periphery to reduce pain sensation

Heroin Pharmacology

• Binds to opiate receptors in:

▫ Reward/pleasure areas of the brain to induce euphoria

▫ Brain, spinal cord, and periphery to reduce pain sensation

Physiological Effects of Heroin

• Effects last 3-5 hrs

▫ Pain relief

▫ Suppressed cough

▫ Constipation

▫ Drowsiness & confusion

▫ Impaired coordination

▫ Reduced heart rate, blood pressure, and breathing

▫ Constricted pupils (“pinpoint pupils”)

▫ Euphoria & pleasure

▫ Hypothermia

Toxicity of Heroin

Acute Toxicity

Heroin depress the medulla, leading to decreased heart/breathing rates

Toxic effects are additive in the presence of alcohol or other depressants

Physical symptoms of heroin overdose: slow heart rate and breathing, blue lips and nails, seizures, muscle spasms, coma, death

Alcohol

• One of the oldest recreational drugs still used by humans

Alcohol

• Metabolism of Alcohol

▫ Absorption into the bloodstream

Primarily in small intestines

Some in stomach

▫ Metabolized (degraded) by the liver

▫ Excreted

Urine

Breath (5% excreted in breath)

Sweat (“drunk smell”)

Alcohol Pharmacology

• CNS depressant

• Affects various neurotransmitter systems

▫ GABA, glutamate, dopamine, opioid

▫ Know for exam: Enhances the inhibitory effects of GABA on its receptor (GABAA Receptor)

Physiological Effects of Alcohol

• Frontal Lobe: Judgement & reasoning altered

• Midbrain: Pleasure, loss of emotional control

• Cerebellum: Loss of coordination & balance

• Pons, Medulla: respiration & heart rate reduced

• Hippocampus: alters long term memory formation

Alcohol Toxicity

• Symptoms of Alcohol Poisoning

▫ Can’t communicate

▫ Irregular/slow heart rate

▫ Hypothermia (low body temp)

▫ Respiratory depression (slowed breathing)

▫ Coma

▫ Death

• Dangerous in combination with other drugs

▫ Especially with other depressants

Cocaine

• Crystalline alkaloid obtained from the coca plant ▫ Not to be confused with the cocoa (chocolate) plant

Cocaine Pharmacology

• Main site of action:

▫ Monoamine reuptake transporters

Inhibits transporter function

Monoamines:

Dopamine

Seratonin

Norepinephrine

• Increases the concentration of monoamines in the synaptic cleft

Cocaine Pharmacology

• Cocaine inhibits the actions of monoamine reuptake transporters

▫ Increases the time that monoamines can bind their receptors

Physiological Effects of Cocaine

• Effects last 1-2 hrs

▫ Increased energy & motor activity

▫ Increased heart rate & blood pressure

▫ Euphoria

▫ Decreased appetite

▫ Mental alertness

▫ Increased body temp

▫ Dilated (large) pupils

Cocaine Toxicity

• Heavy use can cause:

▫ Rapid heart beat

▫ Hallucinations

▫ Paranoid delusions

▫ Tremors and convulsions

▫ Respiratory failure

▫ Heart attack or heart failure

▫ Stroke

Methamphetamine

• Synthetic (man-made), crystal-like, addictive stimulant produced from pseudoephedrine or ephedrine found in cold medicines

Methamphetamine Pharmacology

• Mechanisms of Action

▫ Inhibits the monoamine reuptake transporters (1)

▫ Induces release of monoamines into the synapse (2)

▫ Binds MAO & blocks degradation of monoamines (3)

▫ Causes the monoamine reuptake transporters to act in reverse (4)

Methamphetamine Pharmacology

• Medicinal uses of amphetamines

▫ Treat narcolepsy & ADHD

Physiological Effects of Methamphetamine

• Effects last 8-12 hrs

▫ Effects similar to cocaine use

▫ Irritability and aggression

▫ Anxiety and/or paranoia/nervousness

▫ Increased wakefulness

▫ Tremors/convulsions

▫ Decreased appetite

▫ Insomnia

▫ High blood pressure & increased heart rate

Methamphetamine Toxicity

• Neurotoxic (induces neuron cell death)

▫ Serotonergic neurons

▫ Dopaminergic neurons

• Permanent psychosis (paranoia, hallucinations or repetitive motor activity)

• Hyperthermia (high body temp)

• Kidney failure

• Coma

• Stroke

• Heart attack

Review

• What is the definition of each of the following terms:

• Pharmacology

• Drug

• Stimulant

• Depressant

• Hallucinogen

• Drugs of abuse: Heroin, alcohol, cocaine, and methamphetamine

▫ Know the drug target(s) for each

▫ Know the regions of the brain (if discussed) that each drug acts to elicit its effects

▫ Know the physiological effects of the drugs

Questions