Drugs acting on the CNS

Why should there be drugs to act on CNS…

The answer is simple;

In order to repair or

modify functions

of the CNS

Total loss of sensation

Slight loss of sensation

Normal operating brain

Excitation

Convulsions

Different states of the brain

Death

Death

Total loss of sensation

Slight loss of sensation

Normal operating brain (awake)

Excitation

Convulsions

Anticonvulsants

Anaesthetics

Preanaesthetics

Tranquilizers

CNS stimulantsAnaesthesia antagonists

Death

Death

Mechanisms of action

(on the synapse)

Switch offslow down

Action potential

Switch onSpeed up Modify

Key players at the synapse

Neurotransmitter + Receptor

They can either be inhibitory or excitatory

In. N’trans + In. Rec. = (Reduced Activity)

Exc.N’trans + Exc.Rec = (Increased activity)

Common natural neurotransmitters in the brain

Glutamate (glutamicAcid)

Excitatory

GABA Inhibitory

Serotonin Inhibitory

Glycine Inhibitory

Dopamine Inhibitory

Aspartic acid Excitatory

Acetylcholine Excitatory

Norepinephrine Mostly Excitatory

Modification of the action potentialHow does it occur???

Switch onSpeed up

Increase conc. of excitatory neurotransmitter

Decrease conc. of inhibitory neurotransmitter

Assist stimulation of excitatory receptor

Inhibit stimulation of inhibitory receptor

Cyclohexamines

They include Ketamine Phencyclidine TiletamineTelazol is a combination of tiletamine

and zolazepamThey produce what is referred to as

Dissociative Anaesthesia

Etomidate

This is a sedative hypnotic nonbarbiturate drug, of ultrashortduration

CNS Excitatory Drugs

Excitation

CNS Stimulants Anaesthetic antagonists

CNS StimulantsThese are used for stimulation of some brain

centers like respiratory center. They are also used for; To counteract lethargy and fatigue To reduce sleepiness. To decrease appetite and promote weight loss,

as well as to treat obesity. To improve concentration especially for those

with attentional disorders such as ADHD. Occasionallyused to treat clinical depression.

Common CNS Stimulants

Doxapram Hydrochloride Methlyxanthine derivatives

- Caffeine- Theophylline- Theobromine

Antagonists

KetaminePhysostigmine

Xylazine, xylazine-halothane

Tolazolinehydrochloride

Xylazine, Barbiturates, Ketamine, Acepromazine

Yohimbinehydrochloride

Xylazine, xylazine-ketamine, xylazine-acepromazine

4-Aminopyridine

Used to antagonize…Antagonist