Nervous System drugs act
Classification of CNS drugs • Antipsychotic drugs • Antidepressant and antimanic drugs • Drugs for dementia
Sedative-Hypnotic Drugs Insomnia: -1-5%, more in old women; - trouble in falling asleep or too easily to be waken up; - can be primary or secondary; - harmful to daily life: excessive daytime sleepiness and a lack of energy, feel anxious, depressed, or irritable.
Anxiety is characterized by excessive, exaggerated anxiety and worry about everyday life events with no obvious reasons for worry; - can be extremely debilitating, having a serious impact on daily life.
Benzodiazepines a : diazepam , nitrazepam ( oxazepam , estazol), triazolam), flunitrazepam (with same nucleus and different substituents ) • Barbiturates i : pentobarbital, phenobarbital etc • Others: buspirone , chloral hydrate , meprobamate , etc • Antipsychotic (e.g. chlorpromazine), antidepressant drugs (e.g. amitriptyline) and certain antihistaminic agents (e.g. diphenhydramine)
Pharmacological effects and clinical uses Pharmacological effects and clinical uses (1) Reduction of anxiety: at small doses, used as anxiolytics (not work on schizophrenia) (2) Sedative-hypnotic effects -- at relatively higher doses -- -- no anesthetic effect -- no enzyme induction -- increase stage 2 of NREM, no remarkable effect on REM, decrease slow wave sleep
Other sedative-hypnotic drugs
Antipsychotics • Antidepressant drugs • Antihistaminic agents • Ethanol • Melatonin (pineal hormone)
Antiepiletpic Drugs (AEDs)
Epilepsy is a chronic disorder characterized by
recurrent seizures, which are finite episodes of brain
dysfunction resulting from abnormal discharge of
cerebral neurons
Epilepsy treatment Epilepsy affects 1% population worldwide
• Drug treatment is the main approach.
• ~20-30% of patients develop refractory
epilepsy.
• New drugs and new approaches are
needed
Mechanisms of AEDs
• Modification of ionic conductance.
- N
a
+
- K
+
- Ca2+
• Enhancement of GABAergic (inhibitory)
transmission
• Diminution of excitatory transmission
Phenytoin -----Mechanisms of action
• Binding to and hence prolonging the
status of inactivated state of Na+
channels (main mechanism)
• Blocking L- and N- type Ca2+ channels
(inhibits release of transmitters,
stabilizes membrane)
Schizophrenia Neurological Disorder - impaired ability to perceive,
understand & interpret the environment
• Impaired social and occupational function
• Behavioral Syndrome – predictable or not
• Etiology and biology remain unclear- familial
tendency (heritability), DA and other
neurotransmitters
Incidence consistent worldwide
--1% general population
--10% siblings , parents / offspring, dizygotic twins
--50% monozyg
otic twins
• Environmental factors implicated
--Prenatal stress - infection, famine, war, death of spouse
--Season of birth - winter > summer
--Urban setting > rural setting
• Age of onset
--Men 17 - 27, Women 17 - 37
--Childhood onset extremely rare: 1 in 10,000-100,000
• Outc
o
m
e
--10% good - optimistic
--80% remission without full recovery
--10% no remission
Classifications of Antidepressants Tricyclic Antidepressants (TCAs，三环类抗抑郁药
)
and heterocyclics
• Selective Serotonin Reuptake Inhibitors (SSRIs)
• Selective Norepinephrine Reuptake Inhibitors (NRIs)
• Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)
• Norepinephrine-Dopamine Reuptake Inhibitors (NDRIs)
• Monoamine Oxidase Inhibitors (MAOIs)
• Norepinephrin-Serotonin Releasers
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