Lecture 4: Stimulants and Depressants Flashcards
What two neurotransmitters are the most prevalent in substance abuse?
Dopamine and serotonin.
Caffeine is a…
CNS and metabolic stimulant. And belongs to a group of molecules known as Xanthines.
What are xanthines?
A wider group of stimulants which includes:
- Caffeine (greatest effect on CNS)
- Theophylline (small amounts in tea, in therapeutic doses is an effective bronchial dilator)
- Theobromine (chemical in chocolate that is toxic to dogs, similar but less potent effects than caffeine)
Effects of Xanthines are?
- Increased alertness
- Decrease in fatigue
- Faster and clearer flow of thoughts
- Increased ability to focus
- Better body coordination
What are the pharmacokinetics of caffeine?
- Absorption is very rapid
- The peak levels in blood are hit within 30 minutes
- Half-life is three hours
As a note the tolerance of the CNS effects are much harder to reach than the tolerance of the other effects induced by caffeine i.e. the diuretic effects)
Are Xanthines cross-tolerant?
Yes
What is the mechanism of CNS action with caffeine?
Xanthines, including caffeine, block adenosine receptors in the CNS that normally calm and sedate behaviour.
Can you build a up a dependence on caffeine?
Yes, but it’s mild.
What is the role of adenosine in the brain?
The role of adenosine is to bind to adenosine receptors, these release various proteins that reduce neuron activity and result in drowsiness.
What are the physiological effects of caffeine?
- Increased brain activity (Arousal of EEG brain patterns)
- Increased heart rate
- Constriction of blood vessels therefore increased blood pressure.
What are the risks of caffeine?
- Acid reflux
- Linked to increased risk in cancer, breast disease, heart disease,
osteoporosis. - Moderate tea and coffee drinking need not concern
