pahrmacology cns stimulent

Central Nervous System Stimulants

Two groups of drugs that act primarily to stimulate central nervous system (CNS).

Ø Psychomotor stimulants.
Ø Hallucinogens.

Psychomotor stimulants.

Cause excitement and euphoria, decrease feelings of fatigue, and increase motor activity.
Hallucinogens.

Causes changes in thought Patterns and mood.

Detail of psychomotor stimulant
Ø Methylxanthines
Caffeine
Theobromine
Theophylline

Caffeine, the most widely consumed stimulant in the world, is found in highest concentration in coffee, but is also present in tea, cola drinks, chocolate candy, and cocoa.

Mechanism of action:
Methylxanthines translocation the extra-cellular calcium, increase in cyclic adenosine monophosphate and cyclic guanosine monophosphate caused by inhibition of phosphodiesterase, and blockade of adenosine receptors.
Actions:

a. CNS:
The caffeine contained in one to two cups of coffee (100–200 mg) causes decrease in fatigue and increased mental alertness as a result of stimulating the cortex and other areas of the brain. Consumption of 1.5 g of caffeine (twelve to fifteen cups of coffee) produces anxiety and tremors.
b. Cardiovascular system:
A high dose of caffeine has positive inotropic and chrenotropic effects on the heart. Increased contractility which can be harmful to patients with angina pectoris.
c. Diuretic action: Caffeine has a mild diuretic action that increases urinary output of sodium, chloride, and potassium.

Therapeutic uses:
Caffeine and its derivatives relax the smooth muscles, of the bronchioles (in asthma).
Adverse effects:
Insomnia
Anxiety
Agitation
Convulsions
Cardiac arrhythmias
Headache