What Is an Antipsychotic?

Antipsychotics A class of drugs that are mainly used to treat schizophrenia and mental disorders with psychotic symptoms.

Antipsychotic drugs are divided into two types: typical antipsychotics (traditional antipsychotics) and atypical antipsychotics (nontraditional antipsychotics). Typical antipsychotic drugs Typical antipsychotic drugs represented by chlorpromazine are mainly used to treat schizophrenia and mania; traditional (or typical) antipsychotic drugs are mostly pure dopamine D2 receptor blockers. And the current focus of R & D on antipsychotics is on atypical antipsychotics.

Chinese name: Antipsychotics

Foreign name: Antipsychotic drugs

Classification of antipsychotics

The drugs commonly used in clinical treatment of schizophrenia can be treated according to their pharmacological effects.

Antipsychotics Divided into two categories:

1. Typical antipsychotic drugs are also called traditional antipsychotic drugs.

These drugs were born in 1952, mainly chlorpromazine and haloperidol. By blocking the D2 receptor in the midbrain-marginal-cortex DA pathway, it exerts antipsychotic effects. Due to many adverse drug reactions, it is currently the second-line medication for schizophrenia.

2. Atypical antipsychotics are also called non-traditional antipsychotics.

These drugs were developed after the 1960s, and through the synergistic effect of the two systems of NE and 5HT2, the goal of treating positive symptoms, negative symptoms, emotional symptoms and cognitive impairment of schizophrenia was achieved, while reducing extrapyramidal side effects EPS) and elevated prolactin levels have certain clinical applications. Representative drugs are clozapine, risperidone, olanzapine and quetiapine. Divided into four categories according to chemical structure: phenothiazines, thia anthracenes, butyrylbenzenes and others.

Common antipsychotic drugs

1. Antipsychotics 1. Typical antipsychotics

Representative drugs are chlorpromazine and haloperidol. According to their clinical characteristics, they are divided into two categories: low titer and high titer. The former is represented by chlorpromazine, which has a strong sedative effect, obvious side effects, greater toxicity to the cardiovascular and liver, and a larger dose of medication; the latter is represented by haloperidol, which has a prominent anti- hallucinogenic delusion effect and a weak sedative effect It has low toxicity to cardiovascular and liver, and small therapeutic dose.

2. Antipsychotics 2. Atypical antipsychotics

2.1 Clozapine The first atypical antipsychotic. Created a new situation in schizophrenia drug treatment.

2.2 Risperidone is a widely used atypical antipsychotic drug in the world. The drug is a combination of the chemical structure of haloperidol and ritanserin. At present, oral tablets, oral liquids and long-acting injections are widely used in clinical practice.

2.3 Olanzapine (Zyprexa) is a multi-receptor drug, which is welcomed because of its good efficacy and without causing obvious extrapyramidal symptoms. It was listed in Europe and America in 1996, and completed clinical research in China in 1999. A new olanzapine-soluble glutinous rice paper formulation developed by Eli Lilly and Company recently overcomes the difficulty that patients are unwilling or unable to swallow the drug, and can be dissolved after contact with saliva, which is convenient for some patients.

2.4 Quetiapine (Quetiapine) In 2000, domestically-made quetiapine was approved for marketing after completing Phase I and Phase II clinical trials. American scientists recently published a study that showed that taking the antipsychotic drug sirecon (quetiapine) produced by AstraZeneca in the UK during detoxification can relieve the symptoms of detoxification. In 2007, quetiapine sustained-release tablets seroquelXR was approved by the FDA and has been marketed. It is a 1-day / d treatment for the acute phase of bipolar disorder, the treatment of depression and mania.

2.5 Ziprasidone is the latest atypical broad-spectrum antipsychotic drug developed by Pfizer for the treatment of schizophrenia. This product is a serotonin and dopamine receptor antagonist, especially has strong affinity for 5-HTA2 / DAD2 receptors. The oral and intramuscular formulations of the drug were launched in Sweden in 1998 and September 2000, respectively. Compared with the widely used olanzapine, quinidipine, risperidone, etc., this product is more effective or equivalent to negative symptoms, does not cause weight gain and elevated serum prolactin levels, and has less adverse reactions than all existing Typical antipsychotics. This product is available in two dosage forms: injection and capsule.

2.6 Aripiprazole / Abilitat was developed by Japan's Otsuka Pharmaceutical Co., Ltd., and was marketed abroad in 2002 for clinical treatment of schizophrenia. Domestic aripiprazole has been approved for listing in China. Some scholars call aripiprazole a dopamine system stabilizer based on its ability to maintain a balance between too much and too little.

Mechanisms of Atypical Antipsychotics

At present, it is believed that almost all antipsychotic drugs can block the dopamine receptors in the brain (especially the dopamine D2 receptor) and have antipsychotic effects.

The blocking characteristics of several major receptors are described below:

(1) Dopamine receptor block: mainly blocks D2

(2) Blocking effect of serotonin receptor: mainly blocking 5-HT2A

(3) Blocking effect of adrenergic receptor: mainly a1 receptor

(4) Cholinergic receptor blocking effect: mainly blocks M1 receptor

(5) Histamine receptor blocking effect: mainly blocking H1 receptor

Antipsychotic drugs have a wide range of pharmacological effects. In addition to the blocking effects described above, they also have the effects of strengthening the effects of other central inhibitors, antiemetics, lowering body temperature, inducing epilepsy, and affecting the heart and blood system.

Adverse reactions to atypical antipsychotics

Extrapyramidal reaction

(1) Acute dystonia

It presents strange and involuntary manifestations, including vertebral eyes, torticollis, sloping neck, strange facial expressions and distortions, tongue out, difficulty in opening mouth, angle arch reflexion, and scoliosis.

(2) I ca nt sit still

Appears as uncontrollable agitation, inability to sit still, walk around repeatedly, or step in place.

(3) Parkinson's disease

Inability to exercise, high muscle tone, tremors, and neurological disorders.

(4) tardive dyskinesia

It is characterized by involuntary and rhythmic stereotyped movements.

2. Other adverse nervous system reactions

(1) Malignant syndrome

Consciousness fluctuations, muscle rigidity, high fever, and unstable autonomic nerve function.

(2) Seizures

3. Autonomic nerve side effects Dry mouth, blurred vision, dysuria and constipation.

4. Metabolic endocrine side effects

(1) Increased prolactin secretion

(2) Weight gain

5. Over-sedation of mental side effects

6. Other: liver injury

7. Excessive poisoning

Summary of Antipsychotics

In view of the many pharmacological effects of antipsychotics, in the case of many similar antipsychotics, adverse drug reactions have become the determinants of whether to choose a certain drug. The occurrence of adverse reactions is related to different diseases, types of drugs, methods and dosages of medications, and combined medications. The application of antipsychotic drugs should be avoided as much as possible, and the principle of single drug use should be promoted. The interaction between drugs should be paid attention to, especially the metabolism of drugs and the effects of liver enzymes. ^[1]