Another class of toxic stimulants are
caffeine and nicotine, ampetamines and cocaine.
Caffeine is a methylxanthine.
It's part of the methylxanthine class of drugs.
It is a nonselective A1 and A2 antagonist of adenosine.
And it induces intracellular calcium release.
So for example, in the heart, we need calcium
to cause a cardiac contraction.
So, increasing intracellular calcium results in
increased cardiac contraction.
That's why caffeine causes stronger contraction
and a faster heart rate.
Withdrawal of this medication causes withdrawal lethargy,
withdrawal irritability and withdrawal headache.
"Caffeine free" energy drinks are often sold now.
We speak about energy drinks or 5 hour energy or any of this
other products, they contain non-caffeine methylxanthines.
So, they still have a methylxanthine but they managed
to get around FDA and HPB regulations
by calling themselves caffeine free because
technically they don't have caffeine in them.
Toxicity. CNS stimulation includes tremor,
insomnia and nervousness.
Now, they may not be that harmful on the cardiac tissues
as we had originally suspected,
but there are some long term toxic CNS side effects
like dependance that we have to be worried about.
So, here's a list of the levels of caffeine in
various drinks. You notice that A&W root beer, for example,
is completely decaffeinated, and Starbucks grande caffe mocha
has 530 mg of caffeine with one drink.
Nicotine is the most commonly abused drug on the planet.
Nicotine stimulates the nicotinic cholinergic receptor.
Withdrawal from this drug includes lethargy,
irritability and headache.
And we now use a drug called Champix
or Chantix or varenicline
which is a partial agonist of the
alpha-4-beta-2 nicotinic receptor.
Welbutrin or Zyban is an antidepressant
and anti smoking aid which is a nicotinic antagonist.
It also is used as an antidepressant agent. Nicotine
replacement therapies are often used to treat nicotine addiction.
Gum, patches, candies, the more recent "e-cigarettes"
were intially targeted as nicotine replacement therapy
to get people to stop smoking. But more recently, these new
e-cigarettes or vaping has essentially replaced cigarettes,
and there's no intention of getting people
to quit using e-cigarettes.