A BRIEF OVERVIEW OF DRUGS WITH THEIR CLASSIFICATION AND MECHANISM OF ACTION ,ESPECIALLY FOR PHARM.D STUDENTS.IT INCLUDE ALL D BASIC INFORMATION ABOUT THIS TOPIC .

1. CNS STIMULANTS AND
COGNITION ENHANCERS
By- Nilesh Sharma
(pharm.d 2nd year)
Assignment
on

2. CNS STIMULANTS
These are the drugs whose primarly action is to stimulate the CNS
globally or to improve specific brain function..
They are drugs which increase the muscular (motor) and the mental
(sensory) activities.

3. CNS STIMULANTS ARE CLASSIFIED
AS:
1. CONVULSTANTS : Strychnine , Picrotoxin , Bicuculline ,
Pentylenetetrazol (PTZ).
2. ANALEPTICS: Doxapram .
3. PSYCHOSTIMULANTS: Amphetamines, Methylphenidate,
Atomoxetine, Modafinil , Armodafinil , Pemoline , Cocaine,
Caffeine.

4. CONVULSANTS
A Convulsants is a drugs which induces convulsion and seizures .
Convulsion – A convulsion is medical condition where body muscles
contract and relax rapidly and repeatedly ,resulting in an uncontrol
shaking of the body.
Seizures- uncontrolled electrical activity in the brain ,which may
produce a physical convulsion, minor physical signs, thought
disturbance,or a combination of symptoms.

5. 1.STRYCHNINE:It is an alkaloid from the seeds
of Strychnos nux-vomica, and a
potent convulsant.
Example Strychnine.
Site of action Spinal cord.
Mode of action
Block the postsynaptic
inhibitory
response to glycine by blocking
glycine
receptors. Glycine is the main
inhibitory
transmitter acting on motor
neurons.
End point Tonic convulsion.

7. PICROTOXIN
Obtained from ‘fish berries’ of East
Indies Anamirta cocculus. It is a
potent convulsant— convulsions are
clonic, spontaneous and
asymmetrical. The convulsions are
accompanied by vomiting, respiratory
and vasomotor stimulation.

8. Examples
Site of action
Mode of action
Picrotoxin
Medulla oblongata.
It inhibits the presynaptic
inhibition.
→decrease GABA.
Noncompetitive GABAA receptors
blocker which is a chloride.

9. BICUCULLINE
This synthetic convulsant has picrotoxin
like actions. It is a competitive GABA-A
receptor (intrinsic Cl¯ channel receptor)
antagonist. It is only a research tool.
Pentylenetetrazol (PTZ)
It is a powerful CNS stimulant Low doses cause excitation,
larger doses produce Convulsions Antagonism of PTZ
induced convulsions is an established method of testing
anticonvulsant drugs in laboratory animals

10. ANALEPTICS (RESPIRATORY
STIMULANTS)
These are drugs which stimulate respiration and
can have resuscitative value in coma or fainting.
Mechanical support to respiration and other
measures to improve circulation are more effective
and safe.
Situations in which analeptics may be employed a
(a) As an expedient measure in hypnotic drug poisoning untill
mechanical ventilation is introduced.
(b) Suffocation on drowning, acute respiratory insufficiency.
(c) Apnoea in premature infant.
(d) Failure to ventilate spontaneously after general anaesthesia.

11. DOXAPRAM
.It acts by promoting excitation of central
neurones.
.At low doses it is more selective for the
respiratory centre.
.Respiration is stimulated through carotid and
aortic body chemoreceptors.
.Continuous i.v. infusion of doxapram may
abolish episodes of apnoea in premature infant
not responding to theophylline.

12. USES :
Post-anaesthetic resp. depression
COPD i.e. hypoxemic
Apnoea in premature infants Dose- 2-
5mg/min(max 4mg/kg) slow i.v infusion.
Contraindications:
Resp.fail due to neurological & muscular
diseases.
Epilepsy Side effect:
Restlessness, Tachycardia
High doses: convulsions & arrhythmias

13. PSYCHOMOTOR STIMULANTS
Amphetamine group:
Amphetamine
Dexamphetamine
Methamphetamine
Methylenedioxy
Methampheta(MDMA)
Methylphenedate
Fenfluramine

15. Non-Amphetamine group
Modafinil
Atomoxetine
Sibutramine
Pemoline
Cocaine Methylxanthines:
Caffeine
Theophylline
Theobromine

16. COGNITION ENHANCERS
Cognition is "the mental action or process of acquiring knowledge
and understanding through thought, experience, and the senses.“
It encompasses processes such as knowledge, attention, memory and
working memory, judgment and evaluation, reasoning an d
"computation", problem solving and decision making, comprehension
and production of language,

17. ALZHEIMERS DISEASE
Main pathological features:
Amyloid plaque
Neurofibrillary tangles
Marked ↓ in choline acetyltransferase & loss of cholinergic neurons in
brain.

19. COGNITION ENHANCERS
Indications:
AD, multi infarct dementia
Mild cognitive impairment
learning defects, ADHD in children
CVA, Stroke
Organic psychosyndromes
Sequale of head injury
ECT, brain surgery

20. MECHANISMS
↑ global/regional blood flow
Direct support of neuronal metabolism
Enhancement of neurotransmission
Improvement of discrete cerebral functions

21. CHOLINERGIC INHIBITORS
1 – RIVASTIGMINE
2 – DONEPEZIL
3 – GALANTAMINE

22. DONEPEZIL, RIVASTIGMINE &
GALANTAMINE
Newer reversible Anti cholinesterase
Better penetration in to CNS
Better tolerated & less toxic than tacrine
Clinical results modest & temporary
Donepezil: 5mg OD orally evening ↑ max 10mg after 4 wks
Rivastigmine:1.5 mg orally BD ↑ to 3mg BD after 2 wks
Galantamine:4mg BD orally ↑to 8mg BD after 2 wks

23. Transdermal Rivastigmine patch –
applied every 24hrs

25. REFERENCE: KD.TRIPATHI
For more info-
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