Antipsychotic Medications

Antipsychotic medications work by influencing how information is transmitted between individual brain cells.

The adult brain is estimated to have more than 86 billion nerve cells called neurons. Each neuron in the brain has a single long fiber called an axon, which transmits information to other neurons (see figure Typical Structure of a Nerve). Like wires connected in a vast telephone switchboard, each neuron makes contact with several thousand other neurons.

Information travels down a cell’s axon as an electrical impulse. When the impulse reaches the end of the axon, a tiny amount of a chemical called a neurotransmitter is released to pass information on to the next cell down the line. A receptor on the receiving cell detects the neurotransmitter, which causes the receiving cell to generate a new impulse.

Symptoms of psychosis appear to be caused by excessive activity of cells sensitive to the neurotransmitter dopamine. Therefore, antipsychotic medications work by blocking receptors so that communication between groups of cells is reduced.Symptoms of psychosis appear to be caused by excessive activity of cells sensitive to the neurotransmitter dopamine. Therefore, antipsychotic medications work by blocking receptors so that communication between groups of cells is reduced.

How well different antipsychotic medications block different types of neurotransmitters varies. All antipsychotic medications modulate dopamine levels. Second-generation antipsychotic medications (such as asenapine, clozapine, iloperidone, lurasidone, olanzapine, quetiapine, risperidone, and ziprasidone) also block receptors for serotonin, another neurotransmitter. Newer antipsychotics such as xanomeline work via their effects on acetylcholine. How well different antipsychotic medications block different types of neurotransmitters varies. All antipsychotic medications modulate dopamine levels. Second-generation antipsychotic medications (such as asenapine, clozapine, iloperidone, lurasidone, olanzapine, quetiapine, risperidone, and ziprasidone) also block receptors for serotonin, another neurotransmitter. Newer antipsychotics such as xanomeline work via their effects on acetylcholine.

Clozapine, which also blocks many other receptors, is clearly the most effective medication for psychotic symptoms. But it is not commonly used because of its serious side effects and the need for monitoring with blood tests.Clozapine, which also blocks many other receptors, is clearly the most effective medication for psychotic symptoms. But it is not commonly used because of its serious side effects and the need for monitoring with blood tests.

Antipsychotic medications are divided into 3 groups:

• First-generation (older, conventional, typical) antipsychotics

• Second-generation (atypical) antipsychotics

• Newer types of antipsychotic medications

Currently, about 95% of antipsychotics prescribed in the United States are second-generation antipsychotics. Second-generation antipsychotic medications may relieve positive symptoms (such as hallucinations), negative symptoms (such as lack of emotion), and cognitive impairment (such as reduced mental functioning and attention span). However, research is not clear about whether they relieve symptoms to a greater extent than first-generation antipsychotic medications, but people are just more likely to take them because they have fewer serious side effects and are sometimes less expensive than second-generation antipsychotics.

Clozapine,Clozapine, the first second-generation antipsychotic medication that was developed, is effective in up to half of people who do not respond to other antipsychotic medications. However, due to serious side effects it is usually used only for people who have not responded to other antipsychotic medications.

Some first- and second-generation antipsychotics are available as long-acting injectable preparations that need to be given only once every month or two. These preparations are useful for many people, including those who cannot reliably take oral medications every day.

Antipsychotics with novel actions are currently being studied are becoming available.

Antipsychotic medications have significant side effects, which can include

• Drowsiness

• Muscle stiffness

• Tremors

• Weight gain

• Restlessness

Tardive dyskinesia is a hyperactive involuntary movement disorder that can be caused by chronic antipsychotic medications. It is more likely with first-generation than second-generation medications. Tardive dyskinesia is characterized by puckering of the lips and tongue or writhing of the arms or legs. Tardive dyskinesia may not go away even after the medication is stopped. For tardive dyskinesia that persists, there is no effective treatment, although the medications clozapine or quetiapine may relieve symptoms a little. However, valbenazine has been found to be effective in improving symptoms of tardive dyskinesia. People who must take antipsychotic medications for a long time are checked every 6 months for symptoms of tardive dyskinesia.is a hyperactive involuntary movement disorder that can be caused by chronic antipsychotic medications. It is more likely with first-generation than second-generation medications. Tardive dyskinesia is characterized by puckering of the lips and tongue or writhing of the arms or legs. Tardive dyskinesia may not go away even after the medication is stopped. For tardive dyskinesia that persists, there is no effective treatment, although the medications clozapine or quetiapine may relieve symptoms a little. However, valbenazine has been found to be effective in improving symptoms of tardive dyskinesia. People who must take antipsychotic medications for a long time are checked every 6 months for symptoms of tardive dyskinesia.

Second-generation antipsychotic medications have a significantly lower risk of tardive dyskinesia, muscle stiffness, and tremors than the first-generation antipsychotics. However, some of these medications seem to cause significant weight gain. Some also increase the risk of metabolic syndrome. In this syndrome, fat accumulates in the abdomen, blood levels of triglycerides (a fat) are elevated, levels of high-density cholesterol (HDL, the “good” cholesterol) are low, and blood pressure is high. Also, insulin is less effective (called insulin resistance), increasing the risk of type 2 diabetes. Clozapine can cause seizures or potentially fatal suppression of bone marrow activity (which includes making white blood cells). Thus, In the United States, people who take clozapine are recommended to have their white blood cell count measured weekly, at least for the first 6 months, so that clozapine can be stopped at the first indication that the number of white blood cells is decreasing.. Clozapine can cause seizures or potentially fatal suppression of bone marrow activity (which includes making white blood cells). Thus, In the United States, people who take clozapine are recommended to have their white blood cell count measured weekly, at least for the first 6 months, so that clozapine can be stopped at the first indication that the number of white blood cells is decreasing.

Neuroleptic malignant syndrome is a rare but potentially fatal side effect of antipsychotic medications. It is characterized by muscle rigidity, fever, high blood pressure, and changes in mental function (such as confusion and lethargy).

Long-QT syndrome is a potentially fatal heart rhythm disorder that can be caused by several antipsychotics in both classes. These medications include thioridazine, haloperidol, olanzapine, risperidone, and ziprasidone. People on these medications are monitored with is a potentially fatal heart rhythm disorder that can be caused by several antipsychotics in both classes. These medications include thioridazine, haloperidol, olanzapine, risperidone, and ziprasidone. People on these medications are monitored withelectrocardiography.