Caffeine
Chapter 8
Caffeine
Most used drug in the world
 An alkaloid belonging to a class of
compounds called
METHYLXANTHINES
 Caffeine
 Theophylline
 Theobromine
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History of Caffeine
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Huge history of use
Tea dates back to 2737 B.C. in Chinese legend
Coffee uncertain, but cultivated in Ethiopia in 575
A.D.
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clearly beans chewed & probably brewed way before
Tea comes from Far East
Coffee from the Middle East/North Africa
History
Both coffee and tea historically used as
religious drinks
 Over time, became widely consumed
throughout all levels of society
 Played invaluable role in history of world
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importance in European commerce and
colonial development
COFFEE
1st coffeehouse in Constantinople in 1554
 England
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First coffee house – Oxford - 1650
 1700s London - 2000 coffee houses
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Heavy association with political turmoil
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Governments frequently tried to ban coffee
houses, thinking they could suppress
revolution
COFFEE
Growth of coffee houses in 1700s played
role in reducing gin epidemic
 17th & 18th century - Europeans shipped
& cultivated coffee throughout colonial
landholdings
 Along with tea, was primary commodity of
the European colonies
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TEA
Used in China for thousands of years
before spreading throughout East
 Medicinal use (3000 BC)
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headaches
 to keep awake during prayer
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1st brought to England by Dutch East
India Company in 1657
 Spread throughout Europe by 1700
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Tea & East India Company
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In 1773, East India Tea Company was granted
permission by English Government to sell tea
to American Colonies tax free
Gave them a way to bypass American
merchants
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So when first tea shipment arrived…
• Dressed up as Indians & dumped tea in sea
• Boston Tea Party
• One of precipitating events in American Revolution & also
reason U.S. primarily coffee drinking nation - became
politically incorrect to drink tea
Today
All forms of caffeine legal and fully
integrated into most all societies
 Most widely used psychotropic drug
 HUGE industry
 No illegal market
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Sources of Methylxanthines
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Naturally Occurring Sources
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Coffee
Tea
Chocolate
Kola Nut
Synthetic Sources
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Cola
Pharmaceutical Preparations (alone and in
combo)
Sources of Methylxanthines
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Chocolate - Little caffeine (less than 20 mg)
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Coffee (5 oz cup) 80-150 mg caffeine
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Little effect in producing arousal
Theobromine not very effective
Freeze dried - less
Drip - more
Decaffeinated - pretty much cleared out
Tea
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Has half caffeine of coffee plus theophylline
Theophylline more potent than caffeine
•
Produces some of actions of tea not found in coffee
Sources Methylxanthines
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Soda – Originally from Kola Nut
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Limited by law to 50 mg caffeine
Drugs
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No Doz
100 mg
Vivarin
200
Anacin
32
Excedrin
65
Caffeine & aspirin together make absorption much
better
•
•
increases effectiveness
caffeine changes blood flow - helps headaches
Route of Administration
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Oral administration
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Beverages: Coffee, tea, cocoa,
chocolate milk, cola (fortified)
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Chocolate
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OTC preparations
• Stimulants
• Pain-killers (caffeine synergizes
acetylsalicylic acid)
• Diuretics and cold preparations
Mechanisms of Action
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Some blockade of GABA receptors
Effects are mediated by the blockade of
ADENOSINE receptor
Adenosine is a neuromodulator.
Adenosine receptors coupled to other NT
receptors to modulate effects of that NT.
Adenosine is an inhibitory NM.
Adenosine acts to modulate NE, DA, ACh,
glutamate, and GABA.
Also leads to increased calcium in axon
terminal
CNS Effects
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Normal doses (100-200 mg):
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Alertness, sustained attention, faster thought
Reduced fatigue, lower need for sleep
Fine motor coordination, timing accuracy, and
arithmetic may be impaired
Heavy dosing (1.5 grams a day) may
produce agitation, anxiety, tremors,
panting, and insomnia
PNS Effects
Coronary artery vasodilator &
bronchodilation (smooth muscle
relaxer)
 Increase HR (striated muscle
constrictor)
 Constricts cerebral arteries
 Acts as diuretic (Gotta go pee)
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Side Effects of Caffeine
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Indigestion, palpitations, tremor,
insomnia, headache
Conflicting data on reproductive effects
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May slow growth in utero, especially high
dose
Caffeine may be harmful prior to conception
May increase the risk of spontaneous abortion
• > 4 cups/day
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Osteoporosis
Cholesterol increases
Interactions
People smoke fewer cigarettes after
drinking coffee
 Smokers metabolize caffeine quicker
 Caffeine only makes drunk people
more awake
IT DOES NOT INCREASE TIME TO
SOBRIETY
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Toxicity
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Caffeinism - 10 cups or more per day
 Initial signs: insomnia, restlessness
 muscle tension & shaking, tachycardia
 sensory disturbances may also occur
(ears ringing, light flashes)
 Mild delirium & anxiety attacks may
occur in predisposed individuals
Cardiac arrhythmias at 10 - 20 grams
Lethal Dose around 10 grams
Tolerance
Probably does develop
 Dispositional Tolerance?
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Dependence
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Caffeine is dependence producing (2 weeks at
600mg/day)
Withdrawal effects due to increased
adenosine receptor density and thus
increased adenosine sensitivity
Withdrawal – Not fatal
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Depression
Fatigue
Irritability
Muscle aches
Headaches