Common Psychostimulants: Caffeine and NicotineSourcesPharmacokineticsPharmacodynamicsSide effects

Pharmacology

Xanthine derivatives or methylxanthines

Caffeine Theophylline

Divine Leaf

Caffeine

Most popular drug in the world “Caffeine is useless since it serveth neither

Nourishment nor Debauchery.” --Anonymous, 1650

Plants of 28 genera in 17 families Most common sources are coffee, tea,

chocolate, and kola Coffea arabica and Coffea robusta

Pharmacokinetics Oral administration

Beverages: Coffee, tea, cocoa, chocolate milk, cola (fortified)

Chocolate

Complete absorption from GIT in 30-60 minutes Elimination half-life

ranges from 3 to 10 hrs Accumulation Dosing Longer late in

pregnancy, in utero, elderly

Concentrated in breast milk

Shorter in smokers

Pharmacodynamics: Effects Cortex at normal doses (100-200 mg):

Rewarding effect: Feel competent 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

Medicinal Effects OTC Stimulants

No-Doz 100mg/tab Vivarin 200mg/tab

Analgesics Caffeine synergizes ASA

Anacin 32 mg/tab Excedrin 64.8 mg/tab

Diuretics and cold preparations Asthma products

Bronchodilation

Cardiac Effects

Indirect Stimulation of Catecholamines Epinephrine

Elevated BP, HR

Spinal cord stimulated at toxic doses (2 - 5 grams); cardiac arrhythmias at 10 - 20 grams

Dilates coronary arteries; constricts cerebral arteries

Pharmacodynamic Mechanisms Caffeine and Theophylline

Block GABA receptors Stimulate calcium release with in the cells Blockade of adenosine receptors results in

caffeine induced behavioral stimulation A normal dose blockades 50% of receptors

Adenosine– neuromodulator Adenosine is linked to sleep inducing effects Adenosine, and thus caffeine, act on NE, DA,

ACh , glutamate, and GABA

Caffeinism

Caffeine-induced disorders from DSM-IV Tolerance and Dependence Withdrawal effects due to increased adenosine

receptor density and thus increased adenosine sensitivity

High doses >1000mg/day Psychiatric effects

Conflicting data on reproductive effects May slow growth in utero, especially high dose Caffeine may be harmful prior to conception May increase the risk of spontaneous abortion

How much caffeine?

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5oz 5oz 5oz 1oz 1oz 12oz Tab- Anal- Diur-Coffee Tea Cocoa Choc. C.Milk Cola lets gesics etics

The REAL Thing – Coca-Cola Active ingredient is

phosphoric acid. pH of 2.8 Dissolves a nail in 4

days. Dissolves a tooth in 24-

48 hours.

Trucks carrying Coca Cola syrup (the concentrate) must use Hazardous Material placards.

The distributor of Coke use it to clean the engines of their trucks.