2. Pharmacology
• Different drugs produce different effects within the psyche and
soma
• The interaction between drugs and living organisms is called
pharmacology
• Drug pharmacology relates to the way it is administered,
absorbed, distributed, metabolized, and excreted
• Drugs that act quickly and produce intense effects are more
likely to be abused than are drugs that act slowly
3. Drug Actions
• Drugs affect various organs, including the nervous system.
• The nervous system consists of the central nervous system
(CNS), the autonomic nervous system (ANS), and the
peripheral nervous system (PNS)
• The CNS consists of the brain and spinal cord, and is
composed of nerve cells (neurons)
• Information is transmitted electrically within the neuron, and
chemically between neurons
5. You have approximately 100
billion neurons and 100
trillion synapses in your
brain. How long would it take
to count to a trillion?
A. All day
B. A month
C. A trillion seconds
D. 32,000 years
Allday
A
m
onth
A
trillion
seconds
32,000years
0%
35%
43%
22%
6. Nervous System
• Somatic Nervous System
• Sensory Information
• Autonomic Nervous
System
• Sympathetic Branch –
Fight/Flight/Freeze
• Parasympathetic Branch –
regulate body functions
• Central Nervous System
• Brain & Spinal Cord
14. Your neurotransmitter
• What it does
• What happens if you have too much?
• What happens if you have too little?
15. Chemical Pathways
1. Dopamine (excitatory)
• Found in basal ganglia and
other regions – behavior &
emotions, including pleasure
• Nigrostriatal dopamine
pathway
• Related to muscle rigidity
• Mesolimbic dopamine
pathway
• Related to psychotic behavior
• Possible component of the
“reward” properties of drugs
16. Chemical Pathways
2. Acetylcholine (excitatory)
• Found in the cerebral cortex & basal ganglia
• Involved in Alzheimer’s disease, learning, memory
storage, movement
3. Norepinephrine (excitatory & inhibitory)
• Regulates level of arousal and attentiveness, memory
• May play a role in initiation of food intake (appetite)
17. Chemical Pathways
4. Serotonin (inhibitory or excitatory)
• Found in the brain stem raphe nuclei
• May have a role in impulsivity, aggression, depression,
control of food, and alcohol intake
• Hallucinogenic drugs influence serotonin pathways
5. GABA (Gamma-amino butyric acid) (inhibitory)
• Found in most regions of the brain
• Inhibitory neurotransmitter, sleep, anxiety
19. Chemical Pathways
6. Glutamate (excitatory)
• Found in most regions of the brain
• Excitatory neurotransmitter, involved in long-term
memory
7. Endorphins (inhibitory)
• Opioid-like chemical occurring naturally in the brain
• Play a role in pain relief
20. People who engage in
strenuous exercise
actually emit a
neurotransmitter that
contributes to a “high”
feeling.
A. True
B. False
True
False
4%
96%
21. The neurotransmitter responsible
for control of alertness and the
fight-or-flight response is:
A. GABA
B. Dopamine
C. Serotonin
D. Norepinephrine
GABA
Dopam
ine
Serotonin
Norepinephrine
4%
86%
7%4%
22. This neurotransmitter is
the brain’s major
inhibitory
neurotransmitter
A. Serotonin
B. GABA
C. Endorphins
D. Acetylcholine
Serotonin
GABA
Endorphins
Acetylcholine
14%
4%
39%
43%
23. This neurotransmitter
has a huge influence
on mood
A. Endorphins
B. Glutamate
C. Serotonin
D. Acetylcholine
Endorphins
Glutam
ate
Serotonin
Acetylcholine
4% 4%
89%
4%
26. Lifecycle of a
Neurotransmitter
1. Neurotransmitter precursors are found circulating in the
blood supply
2. Uptake: Selected precursors are taken up by cells, a
process requiring energy
3. Synthesis: Precursors are changed (synthesized) into
neurotransmitters through the action of enzymes
4. Storage: Neurotransmitters are stored in small vesicles
27. Lifecycle of a
Neurotransmitter
5. When the action potential arrives, neurotransmitters are
released into the synapse
6. Released neurotransmitters bind with receptors on the
membrane of the next neuron
7. Neurotransmitters may have excitatory or inhibitory
effects
8. Once a signal has been sent, neurotransmitters are
removed from the synapse; may return or be
metabolized
28. Drug Actions
• Alter neurotransmitter availability
• Agonists - Mimic neurotransmitters
• Antagonists = Occupy neurotransmitter and
prevent its activation
• Interference with reuptake
• Video:
https://www.youtube.com/watch?v=uXREQ
nFGHGA
29. Names of Drugs
• Chemical name: Complete chemical description
of the molecule
• Example: N'-[2-[[5-(dimethylaminomethyl)-2-furyl]
methylsulfanyl]ethyl]-N-methyl-2-nitro-ethene-1,1-diamine
• Generic name: Official (legal) name, listed in
the United States Pharmacopoeia (USP)
• Example: ranitidine
• Brand name: Specific drug or formulation
trademarked by manufacturer; can be patented
for 20 years
• Example: Zantac®
34. Dose-Response
• Dose-response relationship = correlation
between the response and the quantity of
drug administered
• Threshold = the dose at which an effect is
first observed
35. Older men are more
affected by a drug’s
effects than are
older women.
A. True
B. False
True
False
73%
27%
36. Dose
• Effective dose = the dose of a drug that produces a
meaningful effect in some percentage of test subjects
• ED50 refers to the effective dose for half the animal subjects
in a drug test
• Lethal dose = the dose of a drug that has a lethal
effect in some percentage of test subjects
• LD50 refers to the lethal dose for half the animal subjects in
a drug test
• Therapeutic index = LD50/ED50
• Always greater than one
37. If a drug has a lethal dose that is close to its
effective dose, that drug is more dangerous
than if the LD is far from the ED.
A. True
B. False
True
False
12%
88%
38. Mixing medications
with wine causes more
potential health
problems than mixing
medications with beer.
A. True
B. False True
False
29%
71%
39. Dose
• Potency = measured by the amount of a drug
required to produce a given effect
• Toxicity = capacity of a drug to do damage or
cause adverse side effects
• Safety margin = difference between:
• Dose that produces the desired therapeutic effect in
most patients
• Lowest dose that produces an unacceptable toxic
reaction
• Most drugs have an LD1 well above the ED95
40. Women are less likely
today than they were
30 years ago to use
medicines while
pregnant.
A. True
B. False True
False
54%
46%
43. Mechanisms
• Transport in the blood
• Blood-brain barrier
• Effects on all neurons
• Effects on neurotransmitters
• Enzyme induction
• Deactivation
Homeostasis: Humans must maintain their internal environment within certain limits
Temperature
Acidity
Water content
Sodium content
Glucose concentrations
Other physical and chemical factors
Nerve cells (neurons)
Analyze and transmit information
Over 100 billion neurons in system
Four defined regions
Cell body Dendrites Axon Presynaptic terminals
Stimulation of receptors by psychoactive drugs can activate or inhibit a neuron
Glial cells (Glia)
Provide firmness and structure to the brain
Get nutrients into the system
Eliminate waste
Form myelin
Create the blood-brain barrier
Communicate with other glia & neurons
SYNAPSE brain cells do not actually touch. The small gap is called the synapse. When we talk about connections between brain cells, we are referring to the synapse. When a neuron is stimulated and fires, the electrical impulse travels down the axon, the myelin sheath working as an insulator, and is converted to a chemical message at the presynaptic terminals. This chemical travels across the synapse and is taken up by the receiving neuron. The chemical may cause the next neuron to fire (excitatory) or to stay at rest (inhibitory).
At the ends of axons are saclike vesicles containing neurotransmitters which cross the synapse to receptor sites
Chemicals in the receptor sites generate electrical impulses
Drugs that influencing the release, storage, and synthesis of neurotransmitters are classified as presynaptic
Drugs affecting neurotransmitters after they cross the synapse are classified as postsynaptic
C is correct, but it’s the lazy answer!
Gives you an idea of how much activity there really is in your brain.
Sidenote: When a baby is born, they have all the neurons they will ever have, but fewer connections between them *(synapses). Through experience, synapses grow/brain cells connect. By the time they are three years old, children have twice as many connections as an adult. These connections are pruned away from age 10 through adolescence.
Somatic nervous system
Carries sensory information into the central nervous system
Carries motor (movement) information back out to the peripheral nerves
Controls voluntary actions
Acetylcholine is the neurotransmitter at neuromuscular junctions
Sensory information
Voluntary actions
Autonomic nervous system (ANS)
Monitors and controls the body’s internal environment and involuntary functions
Many psychoactive drugs affect the brain and the autonomic nervous system
Two branches often act in opposition
Sympathetic branch - “Fight or flight”
Parasympathetic branch which is responsible for helping to regulate a variety of body functions, including heart rate, breathing, sweating, and digestion.
Central nervous system (CNS)
Consists of the brain and the spinal cord
Has many functions including
Integration of information
Learning and memory
Coordination of activity
Peripheral nervous system (PNS)
Consists of the somatic and autonomic nervous systems
Somatic nervous system
Part of the nervous system that controls movement of the skeletal muscles
Autonomic nervous system (ANS)
Part of the peripheral nervous system that is automatic and involuntary
The autonomic nervous system (ANS) regulates blood pressure, gastrointestinal and urinary functioning, body temperature, sweating, and other involuntary bodily functions
Divided into two branches which work in opposition:
Sympathetic nervous system reacts to situations that require fighting or fleeing (fight-flight-fright syndrome)
Parasympathetic nervous system allows the body to achieve a resting state
Drugs that mimic actions of the sympathetic system are called sympathomimetics
Examples: Amphetamines, cocaine, and caffeine
Drugs that mimic actions of the parasympathetic system are called parasympathomimetics
Examples: Nicotine and the hallucinogen Amanita muscaria
There are two tutorials on Canvas
Also http://outreach.mcb.harvard.edu/animations/brainanatomy.swf
Cerebral cortex outermost layer of the brain, there is a motor cortex, a sensory cortex and the cerebral cortex contains higher mental processes such as reasoning and language.
Cerebral cortex
Part of the cerebrum involved in intellectual functioning
Affects speech, motor movement, sensory perception, hearing, vision, sensory discrimination, memory, language, reasoning, abstract reasoning, and personality
Affected by almost all psychoactive drugs
Cerebrum The cerebrum, also known as the telencephalon, is the largest and most highly developed part of the human brain. It encompasses about two-thirds of the brain mass and lies over and around most of the structures of the brain. The outer portion (1.5mm to 5mm) of the cerebrum is covered by a thin layer of gray tissue called the cerebral cortex. The cerebrum is divided into right and left hemispheres that are connected by the corpus callosum.
Cerebellum: In Latin, the word cerebellum means little brain. The cerebellum is the area of the hindbrain that controls motor movement coordination, balance, equilibrium and muscle tone.
Basal ganglia subcortical brain structures controlling muscle tone
Basal ganglia
Part of the central nervous system which maintains involuntary motor control
Regulates abilities to stand, walk, run, carry, throw, and lift
Parkinson’s disease destroys the basal ganglia
Drugs prescribed for schizophrenia can precipitate Parkinson’s-like behavior
China white (fentanyl) has been linked to brain damage similar to Parkinson’s disease
Hypothalamus a structure found near the bottom of the forebrain. It participates in the regulation of hunger, thirst, sexual behavior and aggression Hypothalamus
Gland situated near the base of the brain
Maintains homeostasis
Controls the pituitary gland, which regulates hormones that affect stress, aggressiveness, heart rate, hunger, thirst, consciousness, body temperature, blood pressure, and sexual behavior
Linked to behavioral and chemical dependencies from alcohol to gambling to obesity
Limbic system connected structures (amygdala, hippocampus) responsible for emotion, memory for location and level of physical activity. Together with the hypothalamus allows for more behavioral control at a more primitive level than the cerebral cortex
Limbic system
Part of the central nervous system that plays a key role in memory and emotion
Consists of many diverse structures in the cerebral hemispheres
Cocaine affects neurotransmitters in the limbic system, creating intense feelings of excitement and joy
Depressants reduce electrical activity in the limbic system, producing feelings of tranquility and relaxation
Midbrain, pons, and medulla – connects the larger structures of the brain to the spinal cord. Cell bodies in this area play important roles in sensory and motor reflexes as well as coordinated control of complex movements. Most of the brain’s neurotransmitters are produced here by relatively few neurons.
Brain stem lower brain stem contains vomiting center and rate of respiration/breathing
The brain stem is located at the point where the brain and spinal cord join
It consists of the medulla oblongata, pons, and midbrain
Regulates functions such as breathing, heartbeat, dilation of the pupil of the eye, blood pressure, and the vomiting reflex
Drugs affecting the brain stem include alcohol and opiates
Pituitary gland The pituitary gland is a pea-sized gland located in the center of the skull, inferior to the hypothalamus of the brain and posterior to the bridge of the nose. It is an important link between the nervous and endocrine systems and releases many hormones which affect growth, sexual development, metabolism and human reproduction.
Periventricular System
Composed of nerve cells above and to either side of the hypothalamus
Implicated in punishment or avoidance behavior
Coupled with the MBF in that stimulation of one inhibits the other
Reticular Activating System The functions of the reticular activating system are many and varied. Among other functions, it contributes to the control of sleep, walking, sex, eating, and elimination. Perhaps the most important function of the RAS is its control of consciousness; it is believed to control sleep, wakefulness, and the ability to consciously focus attention on something. In addition, the RAS acts as a filter, dampening down the effect of repeated stimuli such as loud noises, helping to prevent the senses from being overloaded.
Reticular Activating System (RAS)
Part of the central nervous system
Affects sleep, attention, and arousal
Shuts down during sleep
Many drugs, including barbiturates, LSD, alcohol, and amphetamines, affect the RAS extensively
Stimulants activate the RAS
Medial Forebrain Bundle The medial forebrain bundle is a collection of long projections of nerve cells called axons that plays an important role in the reward system. A collection of structures in the brain, the reward system is involved in producing pleasurable effects in order to regulate human behavior. For this reason, the medial forebrain bundle is sometimes referred to as the reward circuit. Medical researchers believe that this area is one of the primary circuits that affects human behavior.
Medial forebrain bundle (MFB)
Serves as a communication route between the limbic system and the brain stem
Affects pleasure and reward
Sensation of orgasm originates here
Amphetamines and cocaine produce intense euphoria
Basal ganglia subcortical brain structures controlling muscle tone
Basal ganglia
Part of the central nervous system which maintains involuntary motor control
Regulates abilities to stand, walk, run, carry, throw, and lift
Parkinson’s disease destroys the basal ganglia
Drugs prescribed for schizophrenia can precipitate Parkinson’s-like behavior
China white (fentanyl) has been linked to brain damage similar to Parkinson’s disease
The thalamus is a small structure within the brain located just above the brain stem between the cerebral cortex and the midbrain and has extensive nerve connections to both. The main function of the thalamus is to relay motor and sensory signals to the cerebral cortex. It also regulates sleep, alertness and wakefulness.
Limbic system connected structures (amygdala, hippocampus) responsible for emotion, memory for location and level of physical activity. Together with the hypothalamus allows for more behavioral control at a more primitive level than the cerebral cortex
Limbic system
Part of the central nervous system that plays a key role in memory and emotion
Consists of many diverse structures in the cerebral hemispheres
Cocaine affects neurotransmitters in the limbic system, creating intense feelings of excitement and joy
Depressants reduce electrical activity in the limbic system, producing feelings of tranquility and relaxation
The thalamus is a small structure within the brain located just above the brain stem between the cerebral cortex and the midbrain and has extensive nerve connections to both. The main function of the thalamus is to relay motor and sensory signals to the cerebral cortex. It also regulates sleep, alertness and wakefulness.
Function Of The Amygdala
The amygdala is responsible for the perception of emotions (anger, fear, sadness, etc.) as well as the controlling aggression. The amygdala helps to store memories of events and emotions so that an individual may be able to recognize similar events in the future. For example, if you have ever suffered a dog bite, then the amygdalae may help in processing that event and, therefore, increase your fear or alertness around dogs. The size of the amygdala is positively correlated with increased aggression and physical behavior.
The hippocampus is a small organ located within the brain's medial temporal lobe and forms an important part of the limbic system, the region that regulates emotions. The hippocampus is associated mainly with memory, in particular long-term memory. The organ also plays an important role in spatial navigation.
Damage to the hippocampus can lead to loss of memory and difficulty in establishing new memories. In Alzheimer's disease, the hippocampus is one of the first regions of the brain to be affected, leading to the confusion and loss of memory so commonly seen in the early stages of the disease.
Reticular Activating System The functions of the reticular activating system are many and varied. Among other functions, it contributes to the control of sleep, walking, sex, eating, and elimination. Perhaps the most important function of the RAS is its control of consciousness; it is believed to control sleep, wakefulness, and the ability to consciously focus attention on something. In addition, the RAS acts as a filter, dampening down the effect of repeated stimuli such as loud noises, helping to prevent the senses from being overloaded.
Reticular Activating System (RAS)
Part of the central nervous system
Affects sleep, attention, and arousal
Shuts down during sleep
Many drugs, including barbiturates, LSD, alcohol, and amphetamines, affect the RAS extensively
Stimulants activate the RAS
http://learn.genetics.utah.edu/content/addiction/rewardbehavior/
Dopamine Pathways
Dopamine is the neurotransmitter used by the reward pathway (also called the mesolimbic pathway, which is closely linked with the mesocortical pathway). But there are two other important pathways in the brain that use dopamine: the nigrostriatal pathway and the tuberoinfundibular pathway. Generally, drugs that affect dopamine levels affect all three of these pathways.
Nigrostriatal pathway: Substantia nigra to striatum
Motor control
Death of neurons in this pathway is linked to Parkinson's Disease
Mesolimbic and Mesocortical pathways: Ventral tegmental area to nucleus accumbens, amygdala, hippocampus, and prefrontal cortex
Memory, motivation, emotion, reward, desire, and addiction
Dysfunction is connected to hallucinations and schizophrenia
Tuberoinfundibular pathway: Hypothalamus to pituitary gland
Hormone regulation, nurturing behavior, pregnancy, sensory processes
Dopamine and another neurotransmitter called serotonin are released by just a small number of neurons in the brain. But each of these neurons connects to thousands of other neurons in many areas of the brain, giving them a great deal of influence over complex processes.
Serotonin Pathways
Serotonin is another neurotransmitter affected by many drugs of abuse, including cocaine, amphetamines, LSD, and alcohol. Serotonin is made by neurons in the Raphe nuclei. These neurons reach and dump serotonin onto almost the entire brain, as well as the spinal cord.
Serotonin plays a role in many brain processes, including body temperature regulation, sleep, mood, appetite, and pain. Problems with the serotonin pathway are linked to obsessive-compulsive disorder, anxiety disorders, and depression. Most prescription drugs used to treat depression today work by increasing serotonin levels in the brain.
Glutamate and GABA: A System in Balance
Glutamate and GABA (gamma-aminobutyric acid) are the brain's most plentiful neurotransmitters. Over half of all brain synapses use glutamate, and 30-40% use GABA.
Since GABA is inhibitory and glutamate is excitatory, both neurotransmitters work together to control many processes, including the brain's overall level of excitation. Many of the drugs of abuse change the balance of glutamate or GABA, exerting tranquilizing or stimulating effects on the brain. Drugs that increase GABA or decrease glutamate are depressants. Those that decrease GABA or increase glutamate are tranquilizers or stimulants.
Alcohol decreases glutamate activity.
PCP, or "angel dust," increases glutamate activity.
Caffeine increases glutamate activity and inhibits GABA release.
Alcohol increases GABA activity.
Tranquilizers increase GABA activity.
GABA and glutamate regulate action potential traffic. GABA, an inhibitory neurotransmitter, stops action potentials. Glutamate, an excitatory neurotransmitter, starts action potentials or keeps them going.
VIDEO is on Canvas Action potential = a brief electrical signal transmitted along the axon
Neurotransmitters are the “messengers”
Resting action potential is caused by uneven distribution of ions
Action potential occurs when sodium ions move across channels
Blocking channels prevents the action potential and disrupts communication between neurons
VIDEO ON CANVAS
Schematic representation of the release of neurotransmitter molecules from synaptic vesicles in the axon terminal of one neuron and the passage of those molecules across the synapse to receptors in the membrane of another neuron.
Several tutorials and films as resources on Canvas
Break students up into 7 groups, assign each a neurotransmitter, give package of information. Each group reports back to class on what they learned about their assigned neurotransmitter.
Catecholamines
Epinephrine, dopamine, and norepinephrine
Reabsorbed by the neuron that makes them (reuptake)
Increase causes stimulation; decrease causes depression
Amphetamines and cocaine initially increase catecholamines, followed by depletion
Dopamine levels are influenced by marijuana, nicotine, heroin, and amphetamines
Epinephrine released in fight-flight-fright syndrome
Mescaline and MDMA (Ecstasy) reduce norepinephrine
Acetylcholine (ACH)
Synthesized from choline and acetyl coenzyme A
Cholinergic neurons are linked to specific behaviors
Excitatory neurotransmitter in skeletal muscles
Inhibitory neurotransmitter in heart muscle
Reduced ACH receptors associated with Alzheimer’s
Anticholinergic hallucinogens interfere with ACH
Cholinesterase inhibitors such as nerve gas
Serotonin
Inhibitory neurotransmitter in the upper brain stem (tryptaminergic neurons)
Helps regulate pain, sensory perception, eating, sleep, and body temperature
Excessive reabsorption results in depression (antidepressant drugs SSRIs)
Related to hallucinations, psychosis, obsessive-compulsive disorder, aggression or violence
Amino acid tryptophan is needed to synthesize serotonin in tryptaminergic neurons
Gamma-aminobutyric acid (GABA)
Inhibits nerve impulses from being sent from one neuron to another
Alcohol stimulates GABA, producing relaxation and feelings of decreased inhibition
Barbiturates and minor tranquilizers also increase the action of GABA
Peptides
Substances in which amino acid sequences are linked
Modulate the activity of transmitters
Natural endorphins have opiate-like properties
High levels of endorphins in the brain (enkaphalins) could be a factor in morphine dependency
Chronic alcohol use impairs endorphin production
Endorphins, “runner’s high”
Most drugs affect brain activity by increasing or decreasing the activity of various neurotransmitters
Neurotransmitters enable the brain to receive, process, and respond to information by carrying impulses from one neuron to the next
Video is available on Canvas
At the ends of axons are saclike vesicles containing neurotransmitters which cross the synapse to receptor sites
Chemicals in the receptor sites generate electrical impulses
Drugs that influencing the release, storage, and synthesis of neurotransmitters are classified as presynaptic
Drugs affecting neurotransmitters after they cross the synapse are classified as postsynaptic
Neurotransmitters linked to addiction include dopamine, norepinephrine, GABA, and serotonin
Some drugs increase activity and excitation nerve cells (e.g. caffeine)
Sedative-hypnotic drugs make nerve cells less sensitive
Many nerve cells contain autoreceptors that alter the synthesis of neurotransmitters (e.g. LSD)
Show PDR
Stimulants produce wakefulness, a sense of energy
Depressants slow nervous system activity
Opioids (narcotics) reduce pain
Hallucinogens produce altered perceptions
Psychotherapeutics control symptoms mental disorders
Some drugs have effects typical of more than one category
Marijuana
Nicotine
It is important that both legal and illicit drugs be identifiable by appearance
The Physician’s Desk Reference (PDR) includes color photographs of many legally manufactured pharmaceuticals
Illegal drugs are sometimes shaped, marked, or packaged in an identifiable way
Drugs can be tested and identified through chemical analysis
One’s state of mind can influence whether a drug’s effects are euphoric or dysphoric.
Nonspecific effects derive from the user’s unique background, expectations, perceptions, and environment (setting)
Specific effects depend on the presence of a chemical at certain concentrations
Placebo effects are those produced by an inactive chemical that the user believes to be a drug
Especially important in treating pain and psychological depression
The effects of drugs on behavior depend on one’s attitudes toward drugs, emotional state, and previous experiences
Set
The psychological state, personality, and expectations of an individual while using drugs (internal environment)
Setting
The physical and social environment in which drugs are used (external environment)
Placebos are inert substances capable of producing psychological and physiological reactions
Placebo prescriptions are effective because of expectations for the drug
The notion of a drug being euphoric or dysphoric depends a great deal on set
To a large extent, setting determines set
Gender:
Women are more sensitive to drugs because fat stores drugs and water dilutes drugs in the bloodstream
Females are especially affected by drugs during the premenstrual phase of the menstrual cycle and pregnancy
Teratogenic drugs damage the developing fetus
Use of tobacco, coffee, and alcohol during pregnancy increases the risk of miscarriages
Gender:
Women are more sensitive to drugs because fat stores drugs and water dilutes drugs in the bloodstream
Females are especially affected by drugs during the premenstrual phase of the menstrual cycle and pregnancy
Teratogenic drugs damage the developing fetus
Use of tobacco, coffee, and alcohol during pregnancy increases the risk of miscarriages
Because of nonspecific effects, double-blind tests are needed to evaluate the effectiveness of a drug
Neither the test subjects nor the evaluators knows whether a subject is receiving an experimental drug or a placebo until the drug trial is over
REMEMBER THE MOONWALKING BEAR?
Dose-response relationship = correlation between the response and the quantity of drug administered
Threshold = the dose at which an effect is first observed
Some response systems have higher thresholds than others, so dose-response curves can be created for different drug effects
Some drugs have an all-or-none dose-response relationship
The effects of drugs on behavior depend on one’s attitudes toward drugs, emotional state, and previous experiences
Set
The psychological state, personality, and expectations of an individual while using drugs (internal environment)
Setting
The physical and social environment in which drugs are used (external environment)
Because women have a higher percentage of fat, which increases accumulation of drugs that are lipid-soluble, women are more affected. Women are also more affected by water-soluble drugs because of the higher fat percentage in their bodies. A woman and a man who ingest the same amount of alcohol (water-soluble) will show different blood alcohol levels, the woman’s being slightly higher, because a lesser percentage of her body is water, so the concentration is higher.
Safety
Many problems arise from impurities rather than from the drugs themselves
The purity of drugs varies greatly among illegal drugs – heroin has varied from 4% to 69%
Potency refers to a drug’s ability to produce an effect relative to other drugs – some drugs vary naturally in potency
y of drug is determined by levels of dosing. A drug that has a lethal dose that is close to the effective dose is more dangerous.
Alcohol is alcohol.
Drugs vary in the timing of the onset, duration, and termination of their effects
The time course of a drug depends on how the drug is administered, how rapidly is it absorbed, and how it is eliminated from the body
Drug effects can be prolonged by taking additional doses at intervals determined by the time course of the drug
Taking multiple doses too close together will increase the maximum blood level of the drug (cumulative effects)
An estimated 25% of admissions to emergency rooms result from interactions between alcohol and medications
The effects of combining drugs and food can be additive, antagonistic, or synergistic
Taking certain antidepressants with certain foods can result in hemorrhaging and stroke
More than 150 prescription and over-the counter medications interact negatively with alcohol
4 times more likely today than 30 years ago.
Routes of Administration: Oral Ingestion
Absorption from the gastrointestinal (GI) tract is a complicated process
Drugs must withstand the digestive processes and pass through the cells lining the GI tract into the bloodstream
Drugs from the GI tract travel through veins first to the liver, where they may be metabolized
Oral Ingestion
Drugs can be consumed in the form of pills, liquids, tablets, or capsules
Convenient and safe
Not appropriate in emergencies
Slow absorption rate may reduce the amount of the drug to an insufficient level
Can choke on a drug if not conscious
Some ingested drugs cause nausea and vomiting
Because conditions in the gastrointestinal tract change constantly, drug absorption is variable
Intravenous (IV) injection involves putting the drug directly into the bloodstream
Effects are rapid
High concentrations can be delivered
Irritating material can be injected this way
Veins can be damaged over time
Infections can be directly introduced into the bloodstream
Subcutaneous injection (under the skin)
“Skin popping” Can cause necrosis
Intramuscular injection (into a muscle)
Absorption is more rapid from intramuscular injection due to the greater blood supply in muscles
Injection (parenteral drug use)
Reach the brain quickly but carry many risks
In intravenous injection, or mainlining, drugs are administered directly into the bloodstream
In intramuscular injection, drugs are injected into muscle tissue
Injecting drugs just below the layers of the skin is called subcutaneous injection
Unsterile needles pose risk for infectious diseases such as AIDS
Inhalation
The drug moves from the lungs into the bloodstream through capillary walls
Effects are rapid because blood moves quickly from the lungs to the brain
Inhalation
Drugs absorbed into the bloodstream via the lungs
Fast and efficient
Irritates the lungs
Inhaled drugs include volatile anesthetics such as glue, paint thinner, and gasoline, in addition to cigarettes, marijuana, and crack cocaine
Topical
Absorption through the skin can provide slow, steady drug delivery
Absorption through the mucous membranes occurs more rapidly When a user snorts cocaine, the drug is absorbed through the mucous membranes in the nose.
Topical application (transdermal method)
Drugs applied to the skin and absorbed into the bloodstream by placing small disks or patches behind the ear or on the arm or chest
Introduces drugs into the body slowly
Drugs are absorbed directly into the bloodstream at programmed rates
Used to relieve motion sickness, angina pectoris, and nicotine dependency
Transport in the blood
Some drug molecules attach to protein molecules; they are inactive in this state
Free (unbound) drug molecules can move to sites of action in the body
Drugs vary in their affinity for binding with plasma proteins
Blood-brain barrier
Some drugs can’t cross the blood-brain barrier; they act only on peripheral nerves
Only lipid-soluble substances can leave capillaries in the brain
Many brain capillaries are covered with glial cells, also increasing the difficulty for compounds to pass out of the capillaries
Active transport systems may be needed to move chemicals in and out of the brain
Trauma and infections can impair the blood-brain barrier
Effects on all neurons
Used to be believed that drugs worked by influencing some characteristic common to all neurons, such as the cell membrane which is semi-permeable. By influencing the permeability of the membrane, the drug can alter the electrical characteristics of the neuron. With new research, this theory is in dispute, most scientists cite the specific effects on neurotransmitters as the primary way a drug influences the brain/neurons.
Effects on specific neurotransmitter systems
Drugs may alter the availability of a neurotransmitter by changing the rate of synthesis, metabolism, release, or reuptake
Drugs may activate or prevent the activation of a receptor
Combining depressants can cause respiratory depression
Stimulants + antidepressants can lead to overexcitement, high blood pressure, and arrhythmia
Stimulants + depressants can lead to explosive and dangerous behaviors
Cocaine + alcohol produces a potent and toxic substance called cocaethylene
Enzyme induction
When the body’s cells detect the presence of a foreign drug, they trigger production of more of the specific metabolizing enzyme
Causes tolerance
Causes interaction of drugs broken down by the same enzyme
Enzyme activity returns to normal some time after the inducing drug is no longer being used
Enzyme induction and tolerance can occur after use of prescription and OTC drugs, dietary supplements, or illicit drugs
Deactivation: A drug ceases to have an effect when it is excreted unchanged from the body or is chemically changed
The key drug-metabolizing liver enzymes are a group known as CYP450
The resulting metabolite no longer has the same action as the drug
The resulting metabolite can be excreted by the kidneys
TUTORIALS ON CANVAS
Tolerance
Progressively decreasing responsiveness to a drug
Pharmacological tolerance
Adjustment or compensation of the body to the presence of a given drug
Drug disposition (pharmacokinetic) tolerance
Increased metabolism reduces the effect of the subsequent dose
May relate to enzyme activity or alteration of urine pH
Pharmacodynamic tolerance
Sensitivity of neurons change after repeated use of a drug
Can cause withdrawal reactions
Behavioral tolerance
Adjustment or behaviors learned by an individual to compensate for the presence of drugs
Behavioral tolerance
Drug may have the same biochemical effect but a reduced behavioral effect as a drug user learns to compensate for nervous system impairment
Cross-tolerance
Transference of tolerance to a drug to chemically similar drugs
Reverse tolerance
A drug user’s experiencing of the desired effects from lesser amounts of the same drug