SOC 204 Goldberg Ch 5 Week 3
•Download as PPTX, PDF•
0 likes•237 views
Goldberg Drugs Across the Spectrum Pharmacology & Physiology of Drugs
Recommended
More Related Content
What's hot
Viewers also liked
Viewers also liked (20)
Similar to SOC 204 Goldberg Ch 5 Week 3
Similar to SOC 204 Goldberg Ch 5 Week 3 (20)
Recently uploaded
Recently uploaded (20)
SOC 204 Goldberg Ch 5 Week 3
- 1. THE PHARMACOLOGY AND PHYSIOLOGY OF DRUGS Goldberg Chapter 5 SOC 204 Drugs & Society
- 2. How ‘bout them Seahawks? A. 12 for life! Super Bowl bound, baby! B. They got lucky. C. This is me…not caring about football. D. Is there really such a bird? 12 forlife!Theygotlucky. Thisism e… notcaringabo.. Isthere really such a bird? 67% 11%11%11%
- 3. 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
- 4. Nervous System • Peripheral Nervous System • Somatic Nervous System • Autonomic Nervous System • Sympathetic • Parasympathetic • Central Nervous System
- 5. Neuron • Homeostasis • Neurons and Glial Cells • Neurotransmission
- 6. 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% 36% 27% 36%
- 7. The Brain
- 11. Expert Group • What does your neurotransmitter do? • What happens if there is an excess? • What happens if there is a deficit?
- 14. 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
- 15. 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)
- 16. 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
- 17. 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
- 18. People who engage in strenuous exercise actually emit a neurotransmitter that contributes to a “high” feeling. A. True B. False True False 0% 100%
- 19. 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 18% 36% 18% 27%
- 20. This neurotransmitter is the brain’s major inhibitory neurotransmitter A. Serotonin B. GABA C. Endorphins D. Acetylcholine Serotonin GABA Endorphins Acetylcholine 18% 9% 27% 45%
- 21. This neurotransmitter has a huge influence on mood A. Endorphins B. Glutamate C. Serotonin D. Acetylcholine Endorphins Glutam ate Serotonin Acetylcholine 0% 0% 100% 0%
- 22. This neurotransmitter is responsible for feelings of pleasure/reward. A. Glutamate B. Serotonin C. Dopamine D. GABA Glutam ate Serotonin Dopam ine GABA 0% 0% 100% 0%
- 25. 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
- 26. Classifications
- 27. One’s mood while taking a psychoactive drug will affect the experience derived from the drug. A. True B. False True False 0%0%
- 28. Drug Effects • Nonspecific effects • Specific effects • Placebo effects
- 30. Dose • Threshold • Effective dose • Lethal dose • Therapeutic Index = LD50/ED50
- 31. 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 0%0%
- 32. 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
- 33. Routes of Administration Forms and methods of taking drugs oral ingestion inhalation injection topical application
- 34. Distribution
- 35. Mechanisms • Transport in the blood • Blood-brain barrier • Effects on all neurons • Effects on neurotransmitters • Enzyme induction • Deactivation
- 36. Tolerance • Pharmacological • Behavioral • Cross-tolerance • Reverse tolerance Video: https://www.youtube.com/watch?v=8-Qtd6RhfVA
Editor's Notes
- Drugs that act quickly and produce intense effects are more likely to be abused than are drugs that act slowly
- 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
- 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 Information is transmitted electrically within the neuron, and chemically between neurons 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.
- 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
- 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 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.
- 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) 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 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. 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
- 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)
- 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.
- 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
- 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