♠ WHAT IS ANTIPSYCHOTIC DRUGS ---->>
•These drugs are used for the treatment of major psychosis. They are also called 'major tranquilizers' since they reduce agitation and disturbed behavior seen in schizophrenia.
•What is the Classification of antipsychotic drugs.
------>>> These drugs are mainly five types with their subparts.
1). Phenothiazines
a). Chlorpromazine b). Triflupromazine c). Fluphenazine d). Thioridazine
2). Butyrophenones
a). Haloperidol b). Trifluperiodol
3). Thioxanthines a). Flupenthixol
4). Miscellaneous a). Oxypertine b). Tetrabenazine c). Pimozide d). Penfluridol
5). Atypical antipsychotics a). Clozapine b). Risperidone c). Olanzapine
♠ WHAT ARE PHENOTHIAZINES:-
----->>>> • Phenothiazines are three-ringed structures in which two benzene rings are linked by sulfur and a nitrogen atom. Chlorpromazine is an important phenothiazine. The following are the pharmacological actions of phenothiazines in general and those of Chlorpromazine in particular.
• What are the Pharmacological actions of antipsychotic drugs.
----->>>>• They have six types of pharmacological activity.
• 1). Central nervous system: -
--->>>• When Chlorpromazine is given to patients with psychosis, it produces :
i. Psychomotor slowing
ii. Emotional quietening
iii. Decreased initiative
iv. Decreased anxiety Phenothiazines do not have the analgesic effect of morphine. They do not have an anticonvulsant effect.
• 2). Antiemetic effect.
---->>>> Chlorpromazine has a powerful antiemetic impact. This effect is produced by depressing the chemoreceptor trigger zone(CTZ).
• 3). Autonomic nervous system:-
--->>> Chlorpromazine has an alpha-adrenergic blocking effect. It also blocks the action of acetylcholine and 5 - hydroxytryptamine.
• 4). Cardiovascular system: -
--->>>> Chlorpromazine has a hypotensive, myocardial depressant, and anti-fibrillatory effect.
• 5). Endocrine system: Chlorpromazine produces inhibition of ovulation, amenorrhea, and lactation in females. In males, it produces a loss of libido. These effects are produced by blocking the action of dopamine on the hypothalamus and pituitary.
• 6). Various actions: They are :
i) inhibition of hiccough
ii) local anesthetic effect
iii) skeletal muscle relaxant effect.
♠ What is the Absorption, fate, and excretion :
--->>> Chlorpromazineis well absorbed after oral and parenteral administration. A high concentration is found in the lungs, liver, and adrenal glands. It is subjected to enterohepatic circulation. This increases its duration of action. It is metabolized in the liver. The metabolic products are excreted in the urine.
♠ What are the Adverse reactions of antipsychotic drugs.
• 1). CNS effects:- like drowsiness, excitement, psychotic confusion, and parkinsonism.
• 2). ANS effects:- like blurred vision, tachycardia, and constipation. They occur due to the anticholinergic effect.
• 3). Extrapyramidal symptoms:- of parkinsonism like tremor, muscular rigidity. ( Thioridazine produces the least extrapyramidal effect).
• 4). Hemopoietic effects:- like agranulocytosis, thrombocytopenia, and aplastic anemia.
• 5). Endocrine effects:- like gynecomastia, lactation, and menstrual disturbances.
•6). Intolerance:- like skin eruptions, photosensitivity, contact dermatitis, and cholestatic jaundice.
♠ What are the Preparations and dose of antipsychotic drugs.
•1). Chlorpromazine tablets and syrup - 25 to 1000 mg. by mouth.
•2). Chlorpromazine injection 25 to 50mg. by intramuscular injection.
♠ What are the Therapeutic uses of antipsychotic drugs.
• 1). In the treatment of major psychosis.
• 2). To control aggressiveness in children.
• 3). As an antiemetic.
• 4). In the treatment of hiccoughs.
• 5). For pre-anesthetic medication.
♠ WHAT IS HALOPERIDOL: -
--->>> It is a butyrophenone derivative. It produces more sedative and autonomic effects than Chlorpromazine. Dose: 1.5 to 4.5 mg. three times a day.
♠ WHAT IS PIMOZIDE and PENFLURIDOL : -
. - -->>> Both these drugs are diphenyl butyl piperidines. They have a long duration of action. A single dose is sufficient to treat the patient.
♠ WHAT IS ATYPICAL ANTIPSYCHOTICS:-
The characteristics of atypical antipsychotics are.
• 1). Extrapyramidal effects are more minor, and so the margin of safety is more.
• 2). Improve negative symptoms.
• 3). Do not elevate serum prolactin levels.
• 4). Do not produce catalepsy in animals. The atypical antipsychotics are clozapine, risperidone, and olanzapine.
♠ WHAT IS CLOZAPINE:-
• 1). It is an atypical antipsychotic which does not produce extrapyramidal symptoms.
• 2). It also has antiadrenergic (a1) antimuscarinic, antihistaminic and anti- 5 HT effects.
• 3). Agranulocytosis is a significant adverse effect.
• 4). Use: It is a reserve drug in resistant schizophrenia.
♠ WHAT IS RISPERIDONE: -
• 1). It is another atypical antipsychotic.
• 2). It is a benzisoxazole.
• 3). Effects are similar to clozapine
• 4). It blocks adrenergic (a1 and a2), histaminic, and 5-HT receptors.
• 5). It produces fewer extrapyramidal effects.
♠ WHAT IS OLANZAPINE:-
• 1). It is also an atypical antipsychotic.
• 2). It is a dibenzodiazepine compound.
• 3). It does not antagonize az receptor function.
• 4). It does not produce extrapyramidal symptoms.
• 5). Also, it does not make agranulocytosis. It is an advantage over clozapine.
• 6). Adverse effects: dry mouth, sedation, nausea, and weight gain.
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