💊أدويه الجهاز العصبي9
#Pharmcology_of_CNS 9
#CNS
#Antipsychotic_Drugs
بعد اخدنا مقدمة في البوست الفات عن ال antipsychotic drugs الليلة حا نواصل في المواضيع دي👇
✔️Mechanism of action
✔️Actions
✔️Therapeutic uses
✔️Absorption and metabolism
✔️Adverse effects
✔️Mechanism of action
🔘Dopamine antagonism:
〰All of the first-generation and most of the second-generation antipsychotic drugs block D2 dopamine receptors in the brain and the periphery
🔘Serotonin receptor–blocking activity:
〰Most of the second generation agents appear to exert part of their unique action through inhibition of serotonin receptors (5-HT), particularly 5-HT2A receptors.
〰Clozapine has high affinity for D1,D4,5-HT2 muscarinic, and α-adrenergic receptors, but it is also a weak dopamine D2 receptor antagonist
〰Risperidone blocks 5-HT2A receptors to a greater extent than it does D2 receptors
〰aripiprazole is a partial agonist at D2 and 5-HT1A receptors, as well as an antagonist of 5-HT2A receptors.
〰Quetiapine blocks D2 receptors more potently than 5-HT2A receptors
✔️Actions
☑️Antipsychotic effects
▪️All antipsychotic drugs can reduce hallucinations and delusions associated with schizophrenia (known as“positive” symptoms) by blocking D2 receptors in the mesolimbic system of the brain.
▪️The“negative”symptoms, such as blunted affect,apathy, and impaired attention, as well as cognitive impairment, are not as responsive to therapy, particularly with the first-generation antipsychotics.
لكن في بعض الادوية من الجيل الثاني ممكن تحسن ال negative symptoms ال حدٍ ما زي الclozapine
☑️Extrapyramidal effects
▪️Dystonias(sustained contraction of muscles leading to twisting, distorted postures),Parkinson-like
symptoms, akathisia (motor restlessness), and tardive dyskinesia(involuntary movements,usually of the tongue, lips, neck, trunk, and limbs) can occur with both acute and chronic treatment.
لكن احتمالية حدوثها اقل في حالة الجيل الثاني
☑️Antiemetic effects
▪️most of the antipsychotic drugs have antiemetic effects that are mediated by blocking D2receptors of the chemoreceptor trigger zone of the medulla
☑️Anticholinergic effects
▪️Some of the antipsychotics, particularly thioridazine, chlorpromazine, clozapine, and olanzapine, produce anticholinergic effects.
▪️The anticholinergic effects may actually assist in reducing the risk of EPS with these agents.
☑️Other effects
▪️Blockade of α-adrenergic receptors causes orthostatic hypotension and light-headedness.
▪️In the pituitary, antipsychotics block D2 receptors,leading to an increase in prolactin release
▪️Sexual dysfunction may also occur with the antipsychotics due
to various receptor-binding characteristics.
✔️Therapeutic uses
☑️Treatment of schizophrenia
▪️The antipsychotics are considered the only efficacious pharmacological treatment for schizophrenia.
▪️الادوية من الجيل الاول غالبا بيتم استخدامها لعلاج ال positive symptoms اما في الحالات الما بتستجيب للجيل الاول او في حالات الnegative symptoms بيتم استخدام الادوية من الجيل الثاني
☑️Prevention of nausea and vomiting
▪️The older antipsychotics
(most commonly prochlorperazine )
are useful in the treatment of drug-induced nausea.
☑️Other uses
▪️Chlorpromazine is used to treat intractable hiccups.
▪️risperidone and aripiprazole are approved for the management of
disruptive behavior and irritability secondary to autism
▪️Lurasidone and quetiapine are indicated for the treatment of bipolar depression.
▪️aripiprazole and quetiapine are used as adjunctive agents with antidepressants for treatment of refractory depression
✔️Absorption and metabolism
🔘After oral administration, the antipsychotics show variable absorption that is unaffected by food (except for ziprasidone and paliperidone, the absorption of which is increased with food).
✔️Adverse effects
☑️Extrapyramidal effects
▪️غالبا السبب فيها بكون Blocking dopamine receptors وبكدا بكون في عدم توازن بين الdopaminergic و الcholinergic neurons في الحالة دي ممكن نستخدم ال cholinergic blocking زي الbenztropine ودي حا تساعد في استعادة التوازن دا
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