What is the mechanism of action of the phenothiazine antipsychotic drugs?

Phenothiazine antipsychotics are thought to work by blocking the action of dopamine in the brain; however, their exact mechanism of action is unknown. Phenothiazine antipsychotics are classed as typical antipsychotics.

What is the mechanism of action of antipsychotic drugs?

Mechanism of Action

The first-generation antipsychotics work by inhibiting dopaminergic neurotransmission. Their effectiveness is best when they block about 72% of the D2 dopamine receptors in the brain. They also have noradrenergic, cholinergic, and histaminergic blocking action.

What is the mechanism of action of phenothiazines?


As anti-emetics, their mechanism of action is thought to be as antagonists of 5-HT and dopamine receptors in the chemoreceptor trigger zone. In addition, they act as an alpha-adrenergic antagonist.

What medication is an example of a phenothiazine antipsychotic?

The most commonly used phenothiazines as antiemetics are promethazine and prochlorperazine. Chlorpromazine and perphenazine are first generation antipsychotic medications for bipolar disorder and schizophrenia, and they are used much less as antiemetic agents.

What is the basic pharmacology of phenothiazine?

Phenothiazines primarily block postsynaptic neurotransmission by binding to dopamine (D1 and D2), muscarinic, histamine H1, and serotonergic 5-hydroxytryptamine (HT) 2 receptors. Phenothiazines also possess peripheral adrenergic receptor blockade and quinidine-like cardiac effects.

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Do antipsychotics block all dopamine?

Background: Although the principal brain target that all antipsychotic drugs attach to is the dopamine D2 receptor, traditional or typical antipsychotics, by attaching to it, induce extrapyramidal signs and symptoms (EPS).

What are examples of phenothiazines?

Examples of phenothiazines include: chlorpromazine (brand name: Thorazine), fluphenazine (Duraclon), mesoridazine (Serentil), perphenazine (Etrafon and Trilafon), prochlorperazine (Compazine), promazine (Robinul and Anectine), thioridazine (Mellaril), trifluoperazine (Stelazine) and triflupromazine (Robinul).

What are the side effects of phenothiazines?

Constipation, trouble urinating, dryness of mouth, confusion, problems with memory, dizziness or fainting, drowsiness, trembling of the hands and fingers, and problems with muscle movement, such as decreased or unusual movements, are especially likely to occur in elderly patients, who are usually more sensitive than …

What are the indications for phenothiazines?

Phenothiazines are used to treat serious mental and emotional disorders, including schizophrenia and other psychotic disorders. Some are used also to control agitation in certain patients, severe nausea and vomiting, severe hiccups, and moderate to severe pain in some hospitalized patients.

What is the most potent antipsychotic?

Key points

  • High-potency: haloperidol, fluphenazine.
  • Mid-potency: perphenazine, loxapine.
  • Low-potency: chlorpromazine.

Which of the following is side effects of antipsychotic medication?

Side effects of antipsychotics can include the following:

  • Stiffness and shakiness. …
  • Uncomfortable restlessness (akathisia).
  • Movements of the jaw, lips and tongue (tardive dyskinesia).
  • Sexual problems due to hormonal changes.
  • Sleepiness and slowness.
  • Weight gain.
  • A higher risk of getting diabetes.
  • Constipation.

What is a serious and irreversible side effect of phenothiazines?

Phenothiazines can sometimes cause serious unwanted effects. Tardive dyskinesia or tardive dystonia (muscle movement disorders) may occur and may not go away after you stop using the medicine.

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Psychoactive drugs and substances