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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