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Caffeine Chapter 12 Lindsay Screws & Kaitlyn Dalecky.

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Presentation on theme: "Caffeine Chapter 12 Lindsay Screws & Kaitlyn Dalecky."— Presentation transcript:

1 Caffeine Chapter 12 Lindsay Screws & Kaitlyn Dalecky

2 Caffeine Usually consumed for its stimulant effects –(mice/rats ) low doses  stimulant effects; high doses  reversed, reduced activity –(humans) low doses  stimulating and fatigue- reducing effects; high doses  feelings of tension/anxiety Principal physcoactive ingredient in coffee –Coffea arabica Most widely used drug worldwide –80-90% adults –Average = 200-400 mg/day

3 Typical Caffeine Content of Common Food Items and Drugs Brewed coffee 74-83 mg/5 oz. cup Decaffeinated coffee 2-3 mg/5 oz. cup Tea 24-30 mg/5 oz. cup Regular/diet colas 26-58 mg/12 oz. serving Milk/sweet chocolate 6-20 mg/oz. Excedrin 64.8 mg/tablet No Doz 100mg/tablet

4 Caffeine: Pharmacology Theophylline Normally consumed p.o. (drank) –Completely absorbed from the GI tract = 30-60 min Absorption begins in stomach but takes place mainly w/in the small intestine Half-life = varies from person to person –Average = about 4 hours Converted to metabolites by the liver –95% eliminated through urine, 2-5% through feces, the rest through other bodily fluids (saliva) –1-2% excreted unchanged

5 Theophylline Very similar actions of caffeine Three effects: bronchodilation, heart and CNS stimulation Antiasthmatic treatment –Devoted to synthesizing safer asthma medicine Sleep apnea Can be taken p.o. or rectal and injectable form

6 Tolerance, Dependence, and Withdrawal High caffeine consumption  tolerance to cardiovascular and respiratory effects, decreased noticeable effects Low caffeine consumption  little tolerance, more noticeable effects

7 Withdrawal Symptoms Symptoms can occur in individuals who consume as little as 100 mg/day –symptoms = headache, lethargy or fatigue –Means dependency Lasts for a few days, then dissipate –Begins at 18 th hr of abstinence Positive correlation between strength of dependency and severity of withdrawal symptoms

8 Side Effects Little evidence to link w/ serious disease Possibly raises cholesterol levels & BP Directly related to fibrocystic breast disease –Can go away w/ the absence of usage Heartburn Interaction with alcohol –Just as drunk, but more aroused Not recommended for pregnant women, light sleepers, very young/old, and cardiac patients

9 Mechanisms of Action Does not directly influence catecholamine systems Blocks GABA A –R, stimulates Ca 2+ w/in cells  high/toxic doses Blocks A 1 and A 2A –R (adenosine)  low doses Adenosine = part of ATP (energy) –In brain, also acts as a NT –One explanation why first cup of coffee in the morning wakes some people up; refreshes a worker after post- lunch drowsiness; keeps a non-tolerant individual up at night if consumes late-night coffee

10 Caffeine Abuse Caffeinism –Restlessness, nervousness, insomnia, physiological disturbances (tachycardia) Difficult to distinguish from anxiety disorder –Individuals may experience strong withdrawal symptoms and cravings if attempt to stop usage Has characteristics of an abused substance but usually not compulsive and doesn’t affect daily function –RFT of caffeine not due to drug=induced euphoria like those of other abused drugs


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