Intro Chemical signalling Targets for drug action Drug action in CNS Classification of psychotropic drugs

1. CHEMICAL TRANSMISSION AND DRUG ACTION IN THE CNS

2. INTRODUCTION
• Drugs acting on CNS are of special
significance and of major therapeutic
use but also the drugs which are
commonly administered for non-medical
reasons like coffee, tea and nicotine
• CNS is functionally more complex.
Behavior of drug on the individual cell of
brain is different from the whole brain
unlike the other organs
Two reasons
for
understanding
the action of
drugs on CNS
is difficult:

3. CHEMICAL SIGNALING IN THE CNS
CNS produce
neurotransmitter which
start processes in the
body and control the
biological functions
It is important to study
the physiology of brain
and to study chemical
signaling because
whole body is linked
with it.
Drug acting upon CNS
will also produce effects
on the body.
For Example,

4. Adrenaline,
controls the eyes
and little bit dryness
of mouth
Dopamine,
disturbance in its
release leads to
Parkinson’s disease
GABA, is related to
anxiety
CHEMICAL SIGNALING IN THE CNS

5. CHEMICAL SIGNALING IN THE CNS
Neurotransmitters control various process in the body in a range of different time scales. The time scale may be in
Miliseconds
Minutes
Hours
Days
Months
Year
Brain system works like a candy floss into the grand canyon
Candy floss mean number of threads that are placed on a stick and enter into a grand canyon

7. TARGETS FOR DRUG ACTION
Targets for
drug action
Receptors Enzymes
Ion
channels
Carrier
Molecules

8. Receptors
• A protein that recognizes the body’s natural mediator or the drug
• When ligand will bind, it transmits signal and elicits a biological effect
Ion
channels
• Ion channels are proteins in membrane that allow passage of specific ions
only when activated
• Upon receiving signals, it will open and allows the ions to pass
Enzymes
• Biological catalysts that speed up chemical reaction without being changed
• Many drugs act by inhibiting the action of enzymes
Carrier
molecules
• Membrane bounded proteins that transport specific molecules
• Molecule to be transported binds to specific protein for recognition site on
the carrier and then molecule is transferred to other side of membrane
TARGETS FOR DRUG ACTION

9. DRUG ACTION IN CNS
Study action of drug on brain is difficult due to complexity of
neuronal interconnections in the brain
Difficult to predict effects of blocking or enhancing release or
action of one or other neurotransmitters greatly depend upon
External inputs
Influence of glial cells
Range of secondary adaptive responses
Blood brain barrier

11. Drug transport to
specific target in
brain
Direct penetration
Small non-polar
molecules diffuse
passively across
cell membrane
Penetration via
transporters
Transporters
facilitate entry into
brain
DRUG ACTION IN CNS

12. CLASSIFICATION OF PSYCHOTROPIC
DRUGS
Anaesthetic
agents
• Used to produce surgical anesthesia
• For example, halothane, propofol
Anxiolytic
and
Sedatives
• Used to induce sleep and reduce anxiety
• Hypnotics, sedatives, minor tranquilizers
• For example, barbiturates, benzodiazepines
Antipyschoti
cs drugs
• Used to relieve schizophrenic illness
• Neuroleptics, major tranquilizers
• Clozapine, chlorpronazine
Antidepressa
nt drugs
• Used to relieve depressive illness
• Thymoleptics
• Escitalopram

13. Analgesic drugs
• Used to relieve from pain
• For example, opiates and carbamazepine
Psychomotor
stimulants
• Used to induce wakefulness and euphoria
• Psychostimulants
• For example, amphetamine, cocaine, caffeine
Psychotomimetic
drugs
• Used to cause disturbance of perception
• Hallucinogens, psychodysleptics
• For example, mesacline, phencyclidine
Cognition
enhancers
• Used to improve memory and cognitive performance
• Nootropic drugs
• For example, tacrine, donepezil
CLASSIFICATION OF PSYCHOTROPIC
DRUGS

14. Some drugs defy this classification
For example, lithium, dissociative anesthetic, used in the
treatment of manic depressive psychosis and ketamine
It produces psychotropic effect rather similar to those
produced by phecyclidine
CLASSIFICATION OF PSYCHOTROPIC
DRUGS