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1 STIMULANTS Allen Fowler Mycheal Scott Psyc 472.

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1 1 STIMULANTS Allen Fowler Mycheal Scott Psyc 472

2 2 DEFINITION Stimulants are a substance which tends to increase behavioral activity when administered Stimulants are a substance which tends to increase behavioral activity when administered Elevate Mood Elevate Mood Increase Motor Activity Increase Motor Activity Increase Alertness Increase Alertness Decrease need for Sleep Decrease need for Sleep Increase the brains metabolic and neuronal activity Increase the brains metabolic and neuronal activity

3 3 PROCESSES While all stimulants increase behavioral activity the component processes involved differ. While all stimulants increase behavioral activity the component processes involved differ. Neurotransmitter or receptor processes Neurotransmitter or receptor processes Increase neurotransmitters release Increase neurotransmitters release Block reuptake Block reuptake Inhibition of inhibitory neurotransmitters Inhibition of inhibitory neurotransmitters disinhibition disinhibition

4 4 COMMONLY USED STIMULANTS Caffeine Caffeine Nicotine Nicotine Amphetamine Amphetamine Cocaine Cocaine Ephedrine Ephedrine Ritalin Ritalin

5 5 CAFFEINE AND NICOTINE Allen Fowler

6 6 CAFFEINE (picture courtesy Erowid web site)

7 7 CAFFEINE Most commonly consumed psychoactive drug in the world Average intake per person per day is between 80 to 400 milligrams Consumption of caffeine is not considered drug abuse No regulation on sale or use

8 8 CAFFEINE CONTENT Item Coffee (5 oz) Tea (5oz) Cocoa (5oz) Chocolate (1oz) Chocolate milk (1oz) Cola drink (12oz) OTC stimulants OTC analgesics (aspirin) OTC cold remedies Average (mg)

9 9 EFFECTS Caffeine elicits positive effects such as Caffeine elicits positive effects such as Enhanced mental alertness Enhanced mental alertness Sustained intellectual effort Sustained intellectual effort No substantial disruption of coordinated intellectual thought or motor activity No substantial disruption of coordinated intellectual thought or motor activity Increased energy Increased energy A sense of well-being A sense of well-being Faster and clearer flow of thought Faster and clearer flow of thought Reduced fatigue Reduced fatigue Need for sleep is delayed Need for sleep is delayed

10 10 Effects Caffeine may adversely effect tasks involving Caffeine may adversely effect tasks involving delicate muscle coordination delicate muscle coordination Accurate timing Accurate timing Arithmetic skills Arithmetic skills Heavy doses grams Heavy doses grams Agitation Agitation Anxiety Anxiety Tremors Tremors Rapid breathing Rapid breathing Insomnia Insomnia Lethal dose – 10 grams Lethal dose – 10 grams 100 cups of coffee 100 cups of coffee 100 OTC stimulant capsules 100 OTC stimulant capsules

11 11 Effects Caffeine causes a slight stimulant action on the heart Caffeine causes a slight stimulant action on the heart Increases the workload Increases the workload cardiac contractility cardiac contractility Increases cardiac output Increases cardiac output Dilates coronary arteries Dilates coronary arteries More oxygen to the heart More oxygen to the heart

12 12 Effects Caffeine constricts cerebral blood vessels Caffeine constricts cerebral blood vessels Decreases blood flow by about 30% Decreases blood flow by about 30% Can relieve headaches Can relieve headaches Bronchial relaxation Bronchial relaxation Increased secretion of gastric acid Increased secretion of gastric acid Increased urine Increased urine

13 13 Effects Chronic use associated with habituation and tolerance Chronic use associated with habituation and tolerance Quitting may cause withdrawal Quitting may cause withdrawal Headaches Headaches Drowsiness Drowsiness Fatigue Fatigue Negative mood Negative mood

14 14 Reproductive Effects Freely crosses the placenta to the fetus Freely crosses the placenta to the fetus Consumed by estimated 75% of pregnant women Consumed by estimated 75% of pregnant women Breast milk contains levels equal or higher in concentration than mothers plasma Breast milk contains levels equal or higher in concentration than mothers plasma Safety still unresolved Safety still unresolved One study shows 300 mg relatively safe One study shows 300 mg relatively safe Higher doses increased intrauterine growth retardation Higher doses increased intrauterine growth retardation Another study shows 160 mg may cause growth retardation Another study shows 160 mg may cause growth retardation 300mg intake even in the month before doubled the risk of spontaneous abortion 300mg intake even in the month before doubled the risk of spontaneous abortion Recent study shows 6-10 cups per day is associated with increased risk of spontaneous abortion Recent study shows 6-10 cups per day is associated with increased risk of spontaneous abortion Moderate consumption does not increase the risk Moderate consumption does not increase the risk

15 15 Therapeutic Uses Asthma Asthma Bronchial relaxation effects Bronchial relaxation effects Narcolepsy Narcolepsy To help maintain daytime wakefulness To help maintain daytime wakefulness Migraine Migraine Restricts blood flow in the cerebral cortex Restricts blood flow in the cerebral cortex Headache and other minor pain syndromes Headache and other minor pain syndromes In conjunction with aspirin In conjunction with aspirin

16 16 Pharmacokinetics Caffeine is rapidly and completely absorbed Caffeine is rapidly and completely absorbed Significant blood levels reached in minutes Significant blood levels reached in minutes Levels peak in about 2 hours Levels peak in about 2 hours Caffeine is freely and equally distributed through total body water Caffeine is freely and equally distributed through total body water Caffeine can be found in almost equal concentrations throughout body and brain Caffeine can be found in almost equal concentrations throughout body and brain

17 17 Pharmacokinetics Caffeine has 3.5 to 5 hours half life Caffeine has 3.5 to 5 hours half life Extended half life for Extended half life for Elderly Elderly Pregnant women Pregnant women Up to ten hours Up to ten hours Infants Infants Decreased half life for smokers Decreased half life for smokers

18 18 Pharmacokinetics Caffeine is metabolized in the liver by the CYP1A2 subgroup of enzymes into three metabolites Caffeine is metabolized in the liver by the CYP1A2 subgroup of enzymes into three metabolites Theophylline Theophylline Bronchial relaxation Bronchial relaxation Paraxanthine Paraxanthine Theobromine Theobromine Theophylline and Paraxanthine act similar to caffeine Theophylline and Paraxanthine act similar to caffeine About 10% is excreted unchanged About 10% is excreted unchanged

19 19 Mechanism of Action Major site of action –Adenosine receptors –Most potent at adenosine A 1 and A 2A Caffeine works as an antagonism agent –Blocks the adenosine receptor

20 20 Mechanism of Action –Adenosine is a neuromodulator Modulatory effect increasing or decreasing the rate at which neurons fire Works in conjunction with the G protein processes –Adenosine appears to exert sedative, depressant, and anticonvulsant actions Works to slow down the system Important to sleeping –Adenosinergic neurons form a diffuse system No exclusively adenosinergic pathways Adenosine stimulates GABA A inhibitory neurons

21 21 Mechanism of Action –Adenosine is created from the process by which the body breaks down ATP for energy ATP is used throughout the body for energy ATP is used throughout the body for energy Used for high energy bursts such as exercising and running Phosphates form a high energy bond Cells break the phosphate bond to extrapolate the energy When the phosphates are pulled off the adenosine is now free to have an effect in the body

22 22 Mechanism of Action A 1 receptors inhibit excitatory neurons –Dopamine, glutamate, and ACh secreting neurons –Reduces production of cAMP –Slows the activity of the kinase – Reduces occurrence of the action potential A2 A receptors stimulate inhibitory neurons –GABA A neurons –Stimulates production of cAMP –Increases activity of the kinase –Increases occurrence of the action potential picture courtesy “The Brain a Neuroscience Primer ” picture courtesy “The Brain a Neuroscience Primer ”

23 23 Mechanism of Action Adenosine A 1 receptors –Inhibit the release of dopamine and glutamate –Limit the release of acetylcholine Blockade of A 1 receptors –Modest reward –Increased vigilance and mental acuity –Creates arousal effect

24 24 Mechanism of Action Adenosine A 2A receptors –Stimulate GABA A neurons of inhibitory pathways –Inhibit dopamine activity Blockade of A 2A receptors –Increases the potency of endogenous dopamine

25 25 Mechanism of Action Caffeine facilitates a disinhibition process at adenosine receptor sites Caffeine removes the negative effects of adenosine from dopamine receptors increasing dopamine activity –Caffeine does not stimulate dopamine release

26 26 NICOTINE (picture courtesy Erowid web site)

27 27 NICOTINE Primary active ingredient in tobacco One of the three most widely used psychoactive drugs Caffeine Alcohol Few or no therapeutic applications Important because of widespread use and toxicity

28 28 Background Information Indigenous to the Americas 1492 Columbus beaches in West Indies Natives offer them tobacco as gift 1556 first plants taken to Europe 1571 believed to have curing properties for 36 different ailments becomes “duty” of every man of fashion – worth its weight in silver

29 29 Background Information 1881 Cigarette rolling machine invented billion cigarettes produced annually in U.S billion cigarettes sold in U.S billion cigarettes sold in U.S. WWII through mid-1960’s smoking considered cool Now beginning to be shunned as unhealthy and unwise

30 30 Background Information Responsible for the deaths of 1100 Americans every day Each day 6000 American teenagers try their first cigarette 3000 children become regular smokers 1000 of these will die from smoking related disease 9 in 10 smokers become addicted before age 21

31 31 Background Information ½ of all people who have smoked have quit % American adults who smoke has fallen from 50 in 1965 to 25 in 1998 Smoking identified as the major preventable cause death and disability As far as 30 years ago

32 32 Background Information o Nicotine is only one of about 4000 compounds released by burning tobacco o Adverse cardiovascular, pulmonary, and carcinogenic effects are from the other compounds

33 33 Effects Nicotine exerts powerful effects on Nicotine exerts powerful effects on Brain Brain Spinal cord Spinal cord Peripheral nervous system Peripheral nervous system Heart Heart Various other body structures Various other body structures

34 34 Effects Stimulation of the vomit center in the brain stem and sensory receptors in the stomach Stimulation of the vomit center in the brain stem and sensory receptors in the stomach Nausea in early stages of smoking Nausea in early stages of smoking Tolerance develops rapidly Tolerance develops rapidly Reduces weight gain Reduces weight gain probably by suppressing appetite probably by suppressing appetite

35 35 Effects Stimulates release of ADH (antidiuretic hormone) causing fluid retention Stimulates release of ADH (antidiuretic hormone) causing fluid retention Reduces activity of afferent nerve fibers from muscles Reduces activity of afferent nerve fibers from muscles Reduction in muscle tone Reduction in muscle tone May be partially involved with relaxation effect May be partially involved with relaxation effect Higher doses Higher doses Can induce nervousness and tremors Can induce nervousness and tremors Seizures in toxic overdose Seizures in toxic overdose Smoking associated with increased occurrence of panic attacks and panic disorders Smoking associated with increased occurrence of panic attacks and panic disorders

36 36 Effects In the CNS nicotine increases In the CNS nicotine increases Psychomotor activity Psychomotor activity Cognitive functioning Cognitive functioning Sensorimotor performance Sensorimotor performance Attention Attention Memory consolidation Memory consolidation

37 37 Effect Nicotine can improve performance on vigilance and rapid information processing Nicotine can improve performance on vigilance and rapid information processing Effects are greater for working memory rather than long term memory Effects are greater for working memory rather than long term memory Nicotine exerts an antidepressant effect Nicotine exerts an antidepressant effect High smoking rates among depressed individuals may be an attempt at self medication High smoking rates among depressed individuals may be an attempt at self medication

38 38 Effects Nicotine exerts a potent reinforcing action Nicotine exerts a potent reinforcing action Indirect activation of midbrain dopamine neurons Indirect activation of midbrain dopamine neurons Greatest in early phases Greatest in early phases Diminishes over time Diminishes over time Smoking is continued to avoid withdrawal symptoms Smoking is continued to avoid withdrawal symptoms

39 39 Reproductive Effects Smoking during pregnancy increases rates Smoking during pregnancy increases rates spontaneous abortion spontaneous abortion Stillbirth Stillbirth Early postpartum death Early postpartum death Preterm deliveries Preterm deliveries Intrauterine growth retardation is increased 40% Intrauterine growth retardation is increased 40% 2000 infant deaths per year attributed to smoking 2000 infant deaths per year attributed to smoking

40 40 Reproductive Effects Smoking reduces oxygen delivery to the fetus resulting in varying degree of fetal hypoxia Smoking reduces oxygen delivery to the fetus resulting in varying degree of fetal hypoxia Fetus does not receive as much oxygen Fetus does not receive as much oxygen Smoking may result in irreversible intellectual and physical deficiencies Smoking may result in irreversible intellectual and physical deficiencies Increased prevalence of ADHD Increased prevalence of ADHD Lower IQ scores Lower IQ scores

41 41 Tolerance Tolerance Nicotine does not appear induce a pronounced degree of biological tolerance Nicotine does not appear induce a pronounced degree of biological tolerance Increased use in early stages which usually levels off as smoking is continued Increased use in early stages which usually levels off as smoking is continued Smokers adjust nicotine intake to maintain 20 to 40 nanograms per milliliter of plasma Smokers adjust nicotine intake to maintain 20 to 40 nanograms per milliliter of plasma Does induce physiological and psychological dependence Does induce physiological and psychological dependence Habituation Habituation Rebound effect Rebound effect

42 42 Withdrawal Symptoms Intense nicotine craving Intense nicotine craving Irritability Irritability Anxiety Anxiety Anger Anger Difficulty concentrating Difficulty concentrating Restlessness Restlessness Impatience Impatience Increased appetite Increased appetite Weight gain Weight gain Insomnia Insomnia

43 43 Therapy Nicotine replacement therapy doubles successful quit rates Nicotine replacement therapy doubles successful quit rates Skin patches Skin patches Gum Gum Nicotine nasal spray Nicotine nasal spray The use of Zyban has also been shown to increase successful quit rates The use of Zyban has also been shown to increase successful quit rates

44 44 Pharmacokinetics Easily absorbed in the body Easily absorbed in the body Lungs Lungs Buccal and nasal mucosa Buccal and nasal mucosa Skin Skin Gastrointestinal tract Gastrointestinal tract Nicotine is suspended in the minute particles (tars) in smoke Nicotine is suspended in the minute particles (tars) in smoke Orally administered blood levels of nicotine are comparable to smoking Orally administered blood levels of nicotine are comparable to smoking

45 45 Pharmacokinetics Only about 20% of the nicotine in a cigarette is inhaled and absorbed into the bloodstream Only about 20% of the nicotine in a cigarette is inhaled and absorbed into the bloodstream Nicotine which is not immediately absorbed is rapidly metabolized by the hepatic enzyme CYP2A6 Nicotine which is not immediately absorbed is rapidly metabolized by the hepatic enzyme CYP2A6 Inhalation allows controllability of dose Inhalation allows controllability of dose Frequency of breaths Frequency of breaths Depth of breaths Depth of breaths Time in lungs Time in lungs Number of cigarettes Number of cigarettes

46 46 Pharmacokinetics Nicotine is thoroughly distributed in the body Nicotine is thoroughly distributed in the body No barriers to nicotine distribution No barriers to nicotine distribution Rapid brain penetration Rapid brain penetration Crosses placental barrier Crosses placental barrier Appears in all bodily fluids Appears in all bodily fluids The liver metabolizes 80 to 90% before excretion to the kidneys The liver metabolizes 80 to 90% before excretion to the kidneys Primary metabolite is cotinine Primary metabolite is cotinine The elimination half life in chronic users is about 2 hrs The elimination half life in chronic users is about 2 hrs

47 47 Mechanism of Action Nicotine activates specific acetylcholine (ACh) receptors known as nicotinic receptors Nicotinic receptors are located throughout the body –Skeletal muscle –Sympathetic and parasympathetic neurons –CNS

48 48 Mechanism of Action ACh is released, broken down, and reabsorbed very quickly (microsecond) allowing the receptor to respond to new Ach ACh receptors work as a fast first messenger system –Attached directly to ion channels –Binding has an immediate response

49 49 Mechanism of Action picture courtesy pharyngula.org Nicotine replaces ACh at nicotinic receptor Beats out the ACh at the binding site Works as an agonist Opens ion channel allowing depolarization to occur

50 50 Peripheral Nervous System Activation of nicotinic receptors in the PNS Activation of nicotinic receptors in the PNS Increases blood pressure and heart rate Increases blood pressure and heart rate Causes the release of epinephrine from the adrenal glands Causes the release of epinephrine from the adrenal glands Increases the tone, secretions, and activity of the gastrointestinal tract Increases the tone, secretions, and activity of the gastrointestinal tract

51 51 Central Nervous System Nicotinic receptors are widely distributed and may be present at the presynaptic terminals of neurons which secrete Nicotinic receptors are widely distributed and may be present at the presynaptic terminals of neurons which secrete Dopamine Dopamine Acetylcholine Acetylcholine Glutamine Glutamine Activation by nicotine facilitates the release and increases the action in the brain of these neurotransmitters Activation by nicotine facilitates the release and increases the action in the brain of these neurotransmitters

52 52 Central Nervous System Dopamine levels are increased in the Dopamine levels are increased in the Ventral tegmentum Ventral tegmentum Nucleus accumbens Nucleus accumbens Forebrain Forebrain Stimulation of these areas account for the behavioral reinforcement, stimulant, antidepressant, and addictive properties of nicotine Stimulation of these areas account for the behavioral reinforcement, stimulant, antidepressant, and addictive properties of nicotine

53 53 Central Nervous System Increases in acetylcholine contribute to the cognitive potentiation and memory facilitation properties of nicotine Increases in acetylcholine contribute to the cognitive potentiation and memory facilitation properties of nicotine Facilitation of glutaminergic neurotransmissions contribute to the improvement in memory functioning Facilitation of glutaminergic neurotransmissions contribute to the improvement in memory functioning

54 54 Smoking Diseases Smoking accelerates the depositing of fat in the arteries  Increased risk of heart attack and stroke  Smoking weakens the immune system  Smoking irritates the lining in the lungs impairing respiration  Smokers cough  Emphysema picture courtesy quantumclinic.com picture courtesy quantumclinic.com

55 55 Smoking Diseases Lung cancer Lung cancer 90-95% of male deaths 70-75% of female deaths Cancer of the mouth and throat Cancer of the mouth and throat Chewing tobacco Picture courtesy quantumclinic.com

56 56 Smoking Diseases Cardiovascular disease Cardiovascular disease Carbon monoxide decreases amount of oxygen delivered to the heart while nicotine increases the workload Carbon monoxide decreases amount of oxygen delivered to the heart while nicotine increases the workload Carbon monoxide and nicotine increase narrowing (atherosclerosis) and clotting (thrombosis) in the coronary arteries Carbon monoxide and nicotine increase narrowing (atherosclerosis) and clotting (thrombosis) in the coronary arteries Increased risk of coronary heart disease Increased risk of coronary heart disease

57 57 Smoking Diseases About 4000 Americans per year die from lung cancer caused by second-hand smoke About 4000 Americans per year die from lung cancer caused by second-hand smoke deaths per year from heart disease caused by second hand smoke deaths per year from heart disease caused by second hand smoke

58 58 Sources Julien, Robert M. (2001). A Primer of Drug Action (ninth ed.). Caffeine and Nicotine (pp ). NY, New York: Worth Publishers. Julien, Robert M. (2001). A Primer of Drug Action (ninth ed.). Caffeine and Nicotine (pp ). NY, New York: Worth Publishers. Tompson, Richard M. (2000). The Brain: A Neuroscience Primer (third ed.). NY, New York: Worth Publishers. Tompson, Richard M. (2000). The Brain: A Neuroscience Primer (third ed.). NY, New York: Worth Publishers addiction-cigarettes-nicotine-lung-cancer-photos.htm addiction-cigarettes-nicotine-lung-cancer-photos.htm addiction-cigarettes-nicotine-lung-cancer-photos.htm addiction-cigarettes-nicotine-lung-cancer-photos.htm


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