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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