This document discusses CNS stimulants and nootropics, or cognition enhancers. It describes how CNS stimulants produce generalized stimulation of the central nervous system and lists various convulsants, analeptics, and psychostimulants. Nootropics are meant to enhance cerebral functions like memory and are used to treat conditions like Alzheimer's disease, dementia, and learning defects. Common nootropics discussed include cholinergic activators like donepezil and rivastigmine, the NMDA antagonist memantine, and various other drugs like piracetam. Rivastigmine inhibits acetylcholinesterase to increase cholinergic transmission in the brain. Memantine

1. CNS STIMULANTS
&
NOOTROPICS
(COGNITION ENHANCERS)
By: Dr.S.Kameshwaran

2. CNS STIMULANTS
“These are drugs whose primary action is to
stimulate the CNS or to improve specific brain
functions”
• The CNS stimulants mostly produce a generalized
action which may, at high doses, result in
convulsions.

3. CLASSIFICATION
CONVULSANTS
Strychnine,
Picrotoxin,
Bicuculline,
Pentylenetetrazol (PTZ).
ANALEPTICS
Doxapram
PSYCHOSTIMULANTS
Amphetamines,
Methylphenidate,
Atomoxetine,
Modafinil,
Armodafinil,
Pemoline,
Cocaine,
Caffeine.
Many other drugs are capable of causing CNS stimulation as
side effect or at high doses.

4. CONVULSANTS - PICROTOXIN
• 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.
• Picrotoxin acts by prevents Cl¯ channel opening
• Picrotoxin has no therapeutic indication now.

5. Pentylenetetrazol (PTZ, Metrazol, Leptazol)
• It is a powerful CNS stimulant, believed to be
acting by direct depolarization of central
neurons.
• it has also been shown to interfere with
GABAergic inhibition— analogous to picrotoxin.
• Low doses cause excitation,
• large doses produce convulsions which are
similar in pattern to those caused by picrotoxin.

6. ANALEPTICS
• Analeptics are central nervous system stimulants
also stimulate Respiration
Doxapram
• It acts by promoting excitation of central neurons.
• At low doses selectively stimulate respiratory
centre.
• Respiration is stimulated through carotid and aortic
body chemoreceptors.
• Falling BP rises.
• Continuous i.v. infusion of doxapram may abolish
episodes of apnea in premature infant not
responding to theophylline.

7. PSYCHOSTIMULANTS
• These drugs have predominant cortical action; their
psychic effects are more prominent than those on
medullary vital centres.
METHYLPHENIDATE
• It is chemically and pharmacologically similar to
amphetamine.
• Act primarily by releasing NA and DA in the brain.
• produce increase in mental activity
• At high doses produce convulsions.
• Methylphenidate is considered superior to amphetamine
for attention deficit hyperkinetic disorder (ADHD)
• Behaviour and learning ability are improved in 3 out of 4
treated children.
• It can also be used for concentration and attention defect
in adults, and for narcolepsy,

8. PHARMACOKINETICS:
 well absorbed orally,
 metabolized and excreted in urine,
 Twice daily dosing (morning and afternoon) is
enough.
ADR:
• anorexia,
• insomnia,
• Growth retardation,
• abdominal discomfort,
• Bowel upset.

9. NOOTROPICS
(COGNITION ENHANCERS)

10. • These are a heterogenous group of drugs
• developed for use in dementia and other
cerebral disorders.
Dementia
• a chronic or persistent disorder of the mental
processes caused by brain disease or injury and
marked by memory disorders, personality
changes, and impaired reasoning.
Alzheimers Disease

11. The cognition enhancers used in:
• Alzheimer’s disease (AD)
• Multi-infarct dementia (MID).
• Mild cognitive impairment (MCI)
• Mental retardation in children,
• Learning defects,
• Attention deficit disorder.
• Transient ischemic attacks (TIAs),
• cerebrovascular
• accidents, stroke.
• head injury,
• brain surgery

12. A variety of drugs have been briskly promoted
by manufacturers
The mechanism by which they are believed to
act are:
• Increasing cerebral blood flow (CBF)
• Direct support of neuronal metabolism.
• Enhancement of neurotransmission.
• Improvement of cerebral functions, e.g.
memory

13. CLASSIFICATION:
a. Cholinergic activators:
• Tacrine,
• Rivastigmine,
• Donepezil,
• Galantamine
b. Glutamate (NMDA) antagonist:
• Memantine
c. Miscellaneous cerebroactive drugs:
• Piracetam,
• Pyritinol ,
• Dihydroergotoxine
• Citicoline,
• Piribedil,
• Ginkgo biloba

14. CHOLINERGIC ACTIVATORS
• Since brain Ach levels are markedly reduced
and cholinergic neurotransmission is the major
sufferer in AD,
• various approaches to augment brain
Acetylcholine have been tried.
• Cholinergic agonists and conventional
anticholinesterases (anti-ChEs) produce
symptom improvement,

15. RIVASTIGMINE
• This carbamate derivative of physostigmine
inhibits AChE (Acetylcholine esterase)
• Rivastigmine is highly lipid-soluble—enters
brain easily.
• Increase in cholinergic transmission in brain
• Rivastigmine dissociates AChE molecule -
resulting in inhibition of cerebral AChE for up to
10 hours.
• Rivastigmine is indicated in mild to moderate
cases of AD,

16. GLUTAMATE (NMDA) ANTAGONIST:
Memantine
• It is a new NMDA receptor antagonist,
• it has been used in moderate-to-severe AD,
• Beneficial effects have also been noted in parkinsonism.
• Memantine is better tolerated than anti- AChEs used in AD.
ADR:
• Constipation,
• tiredness,
• headache,
• dizziness,
• drowsiness.
Uses:
• Used in moderate-to-severe AD, to replace anti-AChEs
• can be used for other types of dementia as well.

17. THANK YOU