This document discusses various central nervous system stimulants including their classification, mechanisms of action, effects, uses and side effects. It covers psychomotor stimulants like caffeine, cocaine, nicotine and amphetamines. It also discusses hallucinogens such as LSD, PCP and THC. The document provides details on how each drug acts in the brain and body to produce its effects and common adverse reactions.

1. CNS Stimulants
By
Dr. Sajjad Ali
Senior Lecturer Pharmacology

6. Classification
1. Psychomotor Stimulants
 Caffeine
 Cocaine
 Nicotine
 Amphetamine
 Theophylline
2. Hallucinogens
 Dronabinol
 Lysergic acid diethylamide
 Phencyclidine
 Tetrahydocannabinol

7. Psychomotor Stimulants
 These agents produces euphoria
 Cause excitement
 Decrease fatigue

8. Methylxanthines
• Methylxanthines includes;
• theophylline which is found
in tea
• Theobromine found in
cocoa
• Caffeine found mainly in
coffee

9. Mechanism of Action of
Methylxanthine
• Methylxanthines inhibit phosphodiesterase
(PDE), the enzyme that degrades cAMP to AMP
• Thus by inhibiting enzyme PDE , the intracellular
conc. Of cAMP increases as a result
bronchodilation occurs
• Moreover methylxanthine also block adenosine
receptors in CNS, but relation between this action
and the bronchodilating effect is not known

10. Other effects of methylxanthines
• Other effects of methylxanthine which can
occur at therapeutic doses include;
CNS stimulation
Cardiac stimulation
Vasodilation
Slightly increase in B.P.
Diuresis
Increased GIT motility

11. Dose related effects of caffeine
Very high doses of caffeine (2-5 g of
caffeine ) causes stimulation of spinal
cord and more severe CNS as well as
peripheral effects
Tolerance:
 Tolerance can develop rapidly to the
stimulating properties of caffeine
 Withdrawal reactions consist of feeling
fatigue and sedation

12. Dose related effects of caffeine
100-200 mg of caffeine which is contained
in one to two cups of coffee have following
effects;
1. Decrease fatigue
2. Increase mental alertness by stimulating
cortex and other areas of brain
Consumption of 1.5 g of coffee which is
contained in 12-15 cups of coffee causes;
1. Tremors
2. anxiety

13. Clinical uses
1) Aminophylline salt is most commonly used
for the treatment of;
Asthma
COPD
2) Caffeine is commonly used for its diuretic
effects

14. Pharmacokinetics
• Methylxanthines are well absorbed orally
• Distributes throughout the body
including brain
• These drugs can cross placenta to the
fetus and secreted into mother’s milk
• All methylxanthines are metabolized in
liver generally via CYP1A2
• Metabolites are excreted in urine

15. Adverse effects
 Peptic ulcer
Moderate doses cause;
 Insomnia
 Agitation
High doses cause;
 Emesis
 Convulsions
Lethal doses cause(10 g of caffeine/ about 100 cups
of coffee);
 Cardiac arrhythmia
 Death

16. Cocaine
 It is widely available and
highly addictive drug that is
currently abused daily by
more than 3 million people
in US
Mechanism of Action:
 it blocks reuptake of
monoamines
(norepinephrine, serotonin
and dopamine) into
presynaptic nerve endings

17. Actions
CNS:
 It causes stimulation of the cortex and
brainstem
 It increases mental awareness and produces a
feeling of well being and euphoria
 It also produces hallucinations and delusions
 It increases convulsions and tremors

18. Sympathetic Nervous system
 Peripherally it potentiates the action of action
of norepinephrine, and it produces the fight
and flight syndrome
 It causes hyperthermia
Therapeutic Uses:
 It has local anesthetic effects
 It is applied topically

19. Adverse effects
 Anxiety
 Seizures
 Arrhythmias
 Respiratory failure
 Hypertension
 Agitation
 Death (R.I.P)

20. Amphetamine
Mechanism of Action:
 Amphetamine increase the
release of catecholamine in
the synaptic spaces
 It also inhibits the actions of
MAO (monoamine oxidases)
in presynaptic nerve ending
 By doing so more
catecholamine is released
into the synaptic space

21. Therapeutic Uses of Amphetamine
 It is used for the treatment
of following diseases
1. Attention deficit
hyperactivity
disorder(ADHD)
2. Narcolepsy
- Narcolepsy is a sleep disorder
characterized by uncontrolled
bouts of sleepiness during day
time

23. Pharmacokinetics
 It is completely absorbed from the GIT Tract,
metabolized by liver and excreted by urine
 Amphetamine abusers often administer the
drug Via IV route
 Euphoria caused by amphetamine lasts 4-
hours

24. Adverse effects
 Vertigo
 Hypertension
 Insomnia
 Confusion
 Potential for addiction
 Nausea
 Diarrhea

25. Nicotine
 It is the active ingredient in tobacco
 It is not currently used therapeutically
 It is second only to the caffeine as the most
widely used CNS stimulant
 It is second only to alcohol as the most abused
drug

26. Mechanism of Action
 In low doses, it causes ganglionic stimulation by
depolarization
 At high doses, it causes ganglionic blockade
Actions:
CNS:
 It is highly lipid soluble and readily crosses the
blood brain barrier
 At low dosing it produces euphoria and arousal
 It improves attention, learning, problem solving
and reaction time

27.  At high doses it causes respiratory paralysis
and severe hypotension caused by medullary
paralysis
 It is appetite suppressant
Peripheral effects:
 It stimulates sympathetic nervous system as a
result B.P. and H.R. increases
 It also stimulates parasympathetic ganglia as a
result motor activity in GIT increases

28. Pharmacokinetics
 It is highly lipid soluble
 The acute lethal dose is 60mg
 1-2mg of nicotine per cigarette
 It is metabolized in lungs and liver
 It is excreted via urine
 Tolerance develops rapidly

29. Adverse effectsa
 Irritability
 Tremors
 Intestinal cramps
 Diarrhea
 Increased H.R.
 Increased B.P.
 Increased metabolism of a
number of drugs

30. Withdrawal Syndrome
 Nicotine produces physical dependence as it is a
substance having additive potential
 Withdrawal symptoms are;
Irritability
Restlessness
Anxiety
Difficulty in concentrating
Headaches
GIT pain

31. Varenicline
 It is a partial agonist at neuronal nicotinic
receptors in CNS
 It produces less euphoric effects than that by
nicotine
 It is useful in management of smoking
cessation

32. Hallucinogens
Lysergic acid diethylamide:
 It exhibits serotonin agonist activity at presynaptic 5-HT1
receptors in the mid brain it also stimulates 5-HT2
receptors
 It is taken orally
 It causes;
i. Pupillary dilation
ii. Increased B.P.
iii. Increased body temperature
iv. It induces hallucination with brilliant colors
v. It alters mood
vi. Tolerance and physical dependence occurs

33. Adverse effects:
 Hyperreflexia
 Nausea
 Muscular weakness

34. Tetrahydrocannabinol
 The main psychoactive agent contained in
marijuana is tetrahydrocannabinol
 Tetrahydrocannabinol is available as dronabinol
 This product is prescribed to treat emesis and to
stimulate appetite
 Dronabinol can produce euphoria
 Drowsiness
 Relaxation

37.  THC decreases muscle strength and impairs
highly skilled motor activity such as that
required to drive a car
 THC has following side effects;
1. Tachycardia
2. Hypertension
3. Hallucination

38. Phencyclidine (PCP)
 It is also known as angel dust
 It inhibits the reuptake of dopamine, 5-HT and
norepinephrine neurotransmitters into the
presynaptic nerve endings
 It is an analog of ketamine, which produces
dissociative anesthesia (insensitivity to pain
without loss of consciousness) and analgesia

39.  PCP has no therapeutic
importance
 Its manufacturing in USA is
an illegal process

40. THE END