Psychotropic Drugs. Psychotropic Agents which inhibit CNS.

Sedative drugs nonselective depresses CNS

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Mechanism of action Bromides - Enhance and concentrate the processes of inhibition in brain cortex Agents obtained from plants - Decrease the processes of stimulation in CNS

Anxiety is unpleasant state of tension, apprehension, or uneasiness – a fear that seems to arise from an unknown source. Disorders involving anxiety are the most common mental disturbances. The symptoms of severe anxiety are similar to those of fear (such as, tachycardia, sweating, trembling, palpitations) and involve sympathetic activation.

The autonomic nervous system (ANS) controls the body’s internal environment by sending impulses from the central nervous system to the peripheral organs. The ANS is subdivided into the sympathetic nervous system (red) and parasympathetic nervous systems (grey). The sympathetic nervous system, which starts in the hypothalamus, is most active in times of stress, and stimulation of the peripheral organs (blue) produces a panic response (yellow).

Based on early neuroanatomical observations and studies with psychoactive drugs, the septohippocampal circuit has been proposed as a model for anxiety disorders. The circuit that links the septum, amygdala, hippocampus and fornix is thought to process external stimuli and regulate the behavioural response through wider projections in the brain. Hyperstimulation of this putative ‘behavioural inhibition’ circuit, through dysfunctional noradrenergic and serotonergic neurotransmission, has been implicated in producing anxiety, and increased arousal and attention.

Mechanism of action of benzodiazepines GABA is the major inhibitory neurotransmitter in the central nervous system. The GABA A receptor is composed of five sub-units – two alpha, two beta and one gamma sub-unit. Two molecules of GABA activate the receptor by binding to the alpha sub-units. Once activated the receptor allows the passage of negatively charged ions into the cytoplasm, which results in hyperpolarization and the inhibition of neurotransmission.

Mechanism of action of benzodiazepines

Therapeutic uses of Tranquilasers 1.Anxiety disorders (these drugs should be reserved for continued severe anxiety, and then should only be used for short periods of time because of addiction potential) 2.Sleep disorders (the most commonly prescribed – nitrazepam, phenazepam, flurasepam,temazepam, triazolam) 3.Seizures (diazepam is the drug in terminating status epilepticus and grand mal seizures, clonazepam is useful in the chronic treatmant of epilepsy) 4.Muscular disorders (diazepam is useful in the treatment of skeletal muscles spasm such as occur in muscles strain, and in treating spasticity from degenerative disorders, such as multiple sclerosis and cerebral palsy)

Adverse effects of benzodiazepines 1. Lack of tolerance sedation memory impairment lack of concentration motor incoordination muscle weakness acute confusional state 2. Physical dependence (Rebound withdrawl effects) insomnia anxiety apprehension irritability palpitations, tremor, vertigo, sweating 15 to 20% of patients on drug for more than1 year show problems. Therefore there is a need for new anxiolytic drugs with fewer adverse side effects

Neuroleptic drugs (also called antishizophrenic drugs, antipsychotic drugs, major tranquilizers) are used primarily to treat schizophrenia schizophrenia but also effective in other psychotic states, such as manic states and delirium Schizophrenia is a debilitating mental illness characterized by disturbances in thinking, emotional reaction and behavior. Symptoms often include hallucinations, delusions, and cognitive disturbances. Schizophrenia is associated with persistent impairment in a patient's social functioning and productivity, and patients often are under medical care for their entire lives.

Schizophrenia is a severe mental illness characterized by persistent defects in the perception or expression of reality. A person experiencing untreated schizophrenia typically demonstrates grossly disorganized thinking, and may also experience delusions or auditory hallucinations. The term "schizophrenia" translates roughly as "shattered mind," and comes from the Greek σχίζω (schizo, "to split" or "to divide") and φρήν (phrēn, "mind"). Despite its etymology, schizophrenia is not synonymous with dissociative identity disorder, also known as multiple personality disorder or "split personality"; in popular culture the two are often confused. Although schizophrenia often leads to social or occupational dysfunction, there is little association of the illness with a predisposition toward aggressive behavior.

Mechanism of action of neuroleptics

Schizophrenia is associated with increased activity in the dopaminergic system. Many antipsychotic drugs (neuroleptics) exert their therapeutic effects by D2 receptor blockade. There are 2 main categories of neuroleptics – typical (eg chlorpromazine, haloperidol) and atypical (eg clozapine, risperidone). The difference between the two types include fewer extrapyramidal side effects with atypical antipsychotics, and greater efficacy in treatment-resistant patients and against negative symptoms also with atypical antipsychotics. The neuroleptics show varying patterns of selectivity at receptor sites. Older neuroleptics such as chlorpromazine show greater affinity for D2 receptors compared with D1 receptors. Some of the newer agents (eg sulpiride) are highly selective for D2 receptors, whereas clozapine is relatively non-selective for D1 or D2, but has high affinity for D4. Important side effects common to most neuroleptics are extrapyramidal motor disturbances and endocrine disturbances (increased prolactin secretion), which are secondary to dopamine receptor antagonism. Other side effects (eg dry mouth, blurred vision, sedation, hypotension, etc.) are due to blockade of receptors such as α- adrenoceptors, muscarinic cholinergic receptors and histamine H1 receptors. Additionally, rare idiosyncratic reactions can occur; obstructive jaundice has been reported with chlorpromazine therapy, leukopenia can occur with clozapine and thioridazine has been associated with cardiac conduction defects. Typical and atypical neuroleptics

Neuroleptic, or antipsychotic, agents are a group of drugs used to treat schizophrenia and other types of psychoses. Risperidone is a newer ‘atypical’, or ‘second-generation’, neuroleptic and is more selective than the older ‘typical’ neuroleptics. Risperidone can bind to dopamine D2, 5-HT2 and α2 adrenergic receptors in the brain. The efficacy of neuroleptics is thought to be due to antagonism of dopamine receptors in the mesolimbic and mesofrontal systems. The atypical neuroleptics, which have little or no affinity for D1 receptors, do not exhibit some of the side effects associated with D1 antagonism that the older neuroleptics have. The adverse effects associated with atypical neuroleptics, such as tachycardia, impotence and dizziness, are due to the non selective binding to α adrenoreceptors. The mechanism of action of second-generation neuroleptics (risperidone)

Neuroleptic, or antipsychotic, agents are a group of drugs used to treat schizophrenia and other types of psychoses. Haloperidol an older ‘typical’, or ‘first-generation’, neuroleptic is non-selective and binds to a broad range of receptors. It can bind to dopamine D1 and D2, 5-HT2, histamine H1 and α2 adrenergic receptors in the brain. The efficacy of neuroleptics is thought to be due to antagonism of dopamine receptors in the mesolimbic and mesofrontal systems. The adverse effects of typical neuroleptics include tachycardia, impotence and dizziness, and these unwanted effects are caused by non-selective interaction at the α adrenoreceptor. Other adverse effects include and sedation and weight gain, which is due to histamine H1 receptor blockade. The mechanism of action of first-generation neuroleptics (haloperidol)

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