Chapter 4 - Pharmacology and the Physiology of Drug Use

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Raymond Goldberg and Pardess Mitchell, Drugs Across the Spectrum, 9th Edition. © 2024 Cengage. All Rights Reserved. May not be
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Drugs Across the
Spectrum, 9e
Chapter 4: Pharmacology and
Physiology of Drug Use
Raymond Goldberg and Pardess Mitchell, Drugs Across the Spectrum, 9th Edition. © 2024 Cengage. All Rights Reserved. May not be
scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Raymond Goldberg and Pardess Mitchell, Drugs Across the Spectrum, 9th Edition. © 2024 Cengage. All Rights Reserved. May not be
scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Chapter Objectives (1 of 2)
By the end of this chapter, you should be able to:
• Summarize the different parts of the nervous system (central, peripheral,
autonomic, and somatic)
• Describe how neurons communicate electrically and chemically
• Label and explain the parts of a neuron
• Explain the effects of various neurotransmitters
• Summarize the functions of the reticular activating system, hypothalamus,
cerebral cortex, limbic system, basal ganglia, and brain stem

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Raymond Goldberg and Pardess Mitchell, Drugs Across the Spectrum, 9th Edition. © 2024 Cengage. All Rights Reserved. May not be
scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Chapter Objectives (2 of 2)
• Identify the factors that influence the effects of drugs
• Describe how drugs interact with the different body systems
• Describe the additive, antagonistic, and synergistic effects of drugs.
• Contrast between pharmacological tolerance, behavioral tolerance, cross-
tolerance, and reverse tolerance.
• List the mechanisms of how drugs can be administered and discuss the effects
these different routes have on absorption rates.

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scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Pharmacology
• Pharmacology: interaction between drugs and the living organism
• Relates to the way drugs are:
• Administered, absorbed, distributed, metabolized, and excreted
• Dependent on:
• The properties of the drug itself
• The route of administration
• Amount or dosage
• Other drugs in the system
• Previous experience with the drug

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Drug Actions
• Drugs affect the nervous system, which consists of:
• Central nervous system (CNS): brain and the spinal cord
• Peripheral nervous system (PNS)
• Autonomic nervous system (ANS)
• Neurons: nerve cells that function as messengers

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scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Neuron (1 of 2)
• Contains two types of nerve fibers
• Dendrites receive nerve impulses
• Axons send impulses away from the cell
• Neurons sent messages electrochemically
• Messages between neurons are accomplished chemically
• Information within the neuron occurs electrically
• Neurotransmitters: chemical substances
• Electrical impulses originate in the dendrite and pass through the cell through the axon
• Action potential: procedure of how nerve impulses are transmitted
• Synapse: the space between an axon and a dendrite

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Neuron (2 of 2)

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Actions of Drugs
• Neurotransmitters: manufactured in the vesicle of the neuron and travel to the
synaptic space
• Causes the receiving cell to start an electrical impulse
• Drugs most likely have their major effect in the synaptic space
• Presynaptic drugs
• Drugs that impact the neuron responsible for causing the neurotransmitter to
be released
• Postsynaptic drugs
• Drugs that impact the release, storage, and synthesis of neurotransmitters

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Synaptic Transmission

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Neurotransmitters
• Drugs affect brain activity by increasing or decreasing the activity of various
neurotransmitters
• Neurotransmitters affect our emotions, movement, and cognition
• Some drugs mimic the action of neurotransmitters while others block their
actions

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scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Acetylcholine (ACH)
• One of the most common neurotransmitters in the brain
• Drugs that block the action of ACH receptors are called anticholinergic
• Functions
• Excitatory transmitter in the skeletal muscles
• Inhibitory in the heart muscle
• Processing memory and learning
• A number of hallucinogenic drugs impact the action of ACH and are referred to
as anticholinergic hallucinogens

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Serotonin
• Inhibitory neurotransmitter
• Plays a role in:
• Regulating pain, sleep, eating, sensory perception, body temperature
• Research suggests a link between low serotonin levels and depression
• Many depression medications are serotonin reuptake inhibitors that reduce
the amount of serotonin being absorbed  increasing the amount of
serotonin
• Serotonin syndrome is a potentially life-threatening condition resulting from too
much serotonin

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scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Gamma-Aminobutyric Acid (GABA)
• Inhibits nerve cells being sent from one neuron to another
• Drugs that stimulate GABA production leave one feeling relaxed
• Alcohol
• Low levels of GABA are linked with:
• Anxiety, epilepsy, chronic pain

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Catecholamines
• Affect the emotional state
• Function repeatedly because they are reabsorbed by the neuron that
discharges them  reuptake
• Examples include:
• Dopamine
• Epinephrine
• Norepinephrine

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Dopamine
• Plays a significant role in emotional, mental, and motor functions
• Dopamine activates the pleasure system in the brain
• Overproduction of dopamine produces feelings of euphoria  strongly related to
drug-seeking behavior
• Drugs that influence dopamine are:
• Marijuana, nicotine, heroin, and amphetamines
• Dopamine has also been associated with:
• Pathological gambling, compulsive shopping, and hypersexuality

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Epinephrine and Norepinephrine
• During acute stress, epinephrine (AKA: adrenaline) is released
• Part of the fight-or-flight system
• Speeds up coronary blood flow and heart rate
• Norepinephrine
• Inhibits target neurons
• Increases motor activity

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Peptides
• Substances of linked amino acids
• Endorphins
• Enkaphalins are endorphins in the brain
• Actions are similar to morphine and heroin
• Moderates one’s perception of pain
• Brain emits endorphins during stress and pain
• Also emits during strenuous exercise (i.e., runner’s high)

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Central Nervous System
• Consists of the brain and spinal cord

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Reticular Activating System
• Located in the brain stem
• Plays a role in sleep and wake cycles
• Filters out information as it enters the brain
• Allows a person to focus on important stimuli
• Susceptibility to drugs are high
• Implicated in hyperactivity
• Stimulants activate the RAS system, which may help those with hyperactivity
disorder focus

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Hypothalamus
• Located near the base of the brain
• Comparable to a central computer
• Maintains homeostasis
• Stress, heart rate, body temperature
• Linked to chemical and behavioral dependence

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Cerebral Cortex
• Part that distinguishes humans from animals
• Located in the cerebellum
• Essential for thought processes and understanding information
• Influences personality and how we interpret emotions

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Limbic System (1 of 2)
• The emotional center of the brain
• Sorts and stores memory related to emotions
• Brain’s reward circuit

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Limbic System (2 of 2)
The limbic system regulates emotions.

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Medial Forebrain Bundle (MFB)
• Along each side of the hypothalamus
• Serves as a communication route between the limbic system and the brain stem
• The sensation of an orgasm starts here
• When the MFB is stimulated, a person feels pleasure

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Basal Ganglia
• Located on both sides of the brain below the cerebral cortex
• Maintains involuntary muscle control

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Periventricular System
• Comprised of nerve cells above and to either side of the hypothalamus
• Associated with punishment and avoidance behavior
• People experience discomfort when the periventricular system is activated

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Brain Stem
• Connects the brain and spinal cord
• Consists of medulla oblongata, pons, and midbrain
• Regulates vital functions (heart rate, breathing, blood pressure, vomiting reflex)

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scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Peripheral Nervous System
• Serve as transmitting agents that link the body’s extremities to the brain and spinal cord
• Somatic Nervous System
• Control skeletal muscles
• Relay sensory information to the CNS
• Autonomic Nervous System
• Regulates blood pressure, gastrointestinal and urinary functioning, body temperature
• Sympathetic Nervous System
• Fight-or-flight Response
• Parasympathetic Nervous System
• Allows the body to achieve a resting state following an emergency

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scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Body Systems (1 of 2)
• Endocrine System
• Release hormones
• Controlled by the hypothalamus
• Cardiovascular System
• Consists of the heart and blood vessels
• Alcohol can cause the heart muscle to degenerate
• Cocaine increases heart rate and blood pressure
• Smoked drugs interfere with ability of the blood to deliver oxygen

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Raymond Goldberg and Pardess Mitchell, Drugs Across the Spectrum, 9th Edition. © 2024 Cengage. All Rights Reserved. May not be
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Body Systems (2 of 2)
• Respiratory System
• Depressants slow down respiration
• Combing depressants can cause a synergistic effect
• Stimulants increase respiration
• Gastrointestinal System
• Consists of esophagus, stomach, and intestines
• Alcohol irritates and inflames the stomach, small intestine, esophagus, and
pancreas
• Alcohol mixed with aspirin can cause excessive internal bleeding  the two
shouldn’t be mixed

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scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Factors Influencing the Effects of Drugs
(1 of 6)
The effects of a drug are based on their pharmacological or chemical
makeup. There are other factors that impact the effects of a drug.
What do you think the other factors are?

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Raymond Goldberg and Pardess Mitchell, Drugs Across the Spectrum, 9th Edition. © 2024 Cengage. All Rights Reserved. May not be
scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Factors Influencing the Effects of Drugs
(2 of 6)
• Age
• Infants and the elderly are more susceptible to the effects of drugs
• Tolerance for alcohol lessens as people age
• Sex
• Impact of drugs based on chromosomal, hormone, and distribution of body fat as well as
differences in brain structure and function.
• People with XX chromosomes (generally assigned female at birth) have a higher percentage
of body fat and lower percentage of water, making them more susceptible to the actions of
drugs because fat stores drugs and water dilutes the amount of the drug in the bloodstream.

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Raymond Goldberg and Pardess Mitchell, Drugs Across the Spectrum, 9th Edition. © 2024 Cengage. All Rights Reserved. May not be
scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Factors Influencing the Effects of Drugs
(3 of 6)
• Dosage
• The amount of the drug consumed
• Threshold dose: smallest amount of the drug required to produce the desired effect
• Effective dose: the amount of the drug required to produce a specific response
• Lethal dose: the amount of the drug required to result in death
• Purity and Potency
• Purity: quality of a drug
• Potency: drug’s ability to produce a desired effect
Rank these in order from most potent to least potent: heroin, aspirin, morphine

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Dose-Response Curve

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Factors Influencing the Effects of Drugs
(4 of 6)
• Drug Interactions
• Some drugs cannot be mixed
• An estimated 25% of hospital admissions result from interactions between
alcohol and some other medication
• Effects can be additive, antagonistic, or synergistic
• Additive: the cumulative effects of two drugs
• Antagonistic: drugs that negate the effects of other drugs
• Synergistic: the combined effects of two drugs are greater than if they were
added together

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Factors Influencing the Effects of Drugs
(5 of 6)
• Tolerance
• A state of progressively decreasing responsiveness of a drug
• Pharmacological tolerance: body adjusts to the presence of the drug
• Behavioral tolerance: an person learns to adjust to the presence of the drug
• Cross tolerance: people who develop tolerance to a drug will develop
tolerance to chemically similar drugs
• Reverse tolerance: a drug user will feel the desired effects from lesser
amounts

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Factors Influencing the Effects of Drugs
(6 of 6)
• Set and Setting
• Set refers to the drug user’s psychological makeup, personality, mood, and
expectations when using the drug
• Setting refers to the social and physical environment in which drugs are
taken.
• Placebos: inert substances capable of producing an effect
• May provide relief for 30-40% of the patients they are prescribed for
• They are effective because of the expectations for the drug

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Methods of Administration (1 of 2)
List the different ways drugs can be taken into the body.

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Methods of Administration (2 of 2)
• Oral Ingestion
• Injection
• Intravenous
• Intramuscular
• Subcutaneous
• Topical application
• Inhalation

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scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Summary
Click the link to review the objectives for this presentation.
• Link to Objectives