Antipsychotic Drugs

An antipsychotic drug, sometimes called a neuroleptic, is a prescription medication used to treat psychosis. Psychosis is a major psychiatric disorder characterized by derangement or disorganization of personality and/or by the inability to tell what is real from what is not real, often with hallucinations, delusions, and thought disorders. People who are psychotic often have a difficult time communicating with or relating to others. Sometimes they become agitated and violent. They may hear voices, see things that aren't really there, and have strange or untrue thoughts, such as believing that other people can hear their thoughts or are trying to harm them. They may also neglect their appearances and may stop talking or talk only "nonsense."

Among the conditions considered to be psychoses are schizophrenia, major depression, and bipolar affective disorder (manic depression). Psychosis can arise from emotional or organic causes. Organic causes include brain tumors, drug interactions, and substance abuse. Antipsychotic drugs do not cure mental illness, but can reduce some of the symptoms or make them milder. The medicine may improve symptoms enough for the person to undergo counseling and live a more normal life. The type of antipsychotic medicine prescribed depends on the type of mental problem the patient has.

The vast majority of antipsychotics work by blocking the absorption of dopamine, a chemical that occurs naturally in the brain and is responsible for causing psychotic reactions, especially those that happen as a result of mental illness. Dopamine is one of the substances in the brain responsible for transmitting messages across the gaps, or synapses, of nerve cells. Too much dopamine in a person's brain speeds up nerve impulses to the point of causing hallucinations, delusions, and thought disorders. By blocking the dopamine receptors, antipsychotics reduce the severity of these symptoms. The brain has several types of dopamine receptors, and their unselective blockage by antipsychotic drugs causes the side effects.

When a patient takes an antipsychotic drug, he or she enters what is called a neuroleptic state. Impulsiveness and aggression decrease as do concern and arousal about events going on in the environment outside the person. The person taking the drug has fewer hallucinations and delusions as well. Once these symptoms are controlled by antipsychotic drugs, he or she can live a more normal life, and physicians can more easily treat the cause of the psychosis.

Antipsychotic medications were not used in the United States before 1956. The first drug used to treat psychosis was reserpine, which is made from a plant called rauwolfia. Reserpine was first made in India, where rauwolfia had been used to treat psychotic symptoms for centuries. Chlorpromazine, which was invented at about the same time and marketed under the name Thorazine, soon became the most favored drug. Once these and other antipsychotic medicines were introduced in the United States, they gained widespread acceptance for the treatment of schizophrenia. The use of these drugs allowed the release of many people who had been confined to mental institutions.

Antipsychotic drugs are also known as neuroleptics or major tranquilizers. Several types of these drugs are available, such as haloperidol (Haldol), lithium (Lithonate), chlorpromazine (Thorazine), and thioridazine (Mellaril). The newer antipsychotics include risperidone (Risperdal), quetiapine (Seroquel) and olanzapine (Zyprexa). These medicines are available only with a physician's prescription. The recommended dosage depends on the type of antipsychotic drug, the condition for which it is prescribed, and other factors. Despite their benefits, antipsychotic medicines have a number of strong side effects.

Although it usually takes at least two weeks for the drug to work on symptoms of psychosis, side effects often show up sooner. The most severe include muscle rigidity, muscle spasms, twitching, and constant movement. Tardive dyskinesia (TD)—a rhythmic, uncontrollable movement of the tongue, lips, jaw, or arms and legs—develops after a mental patient has taken an antipsychotic drug for a longer period of time. Twenty-six percent of chronically mentally ill people who are, or have been hospitalized develop TD. Often these side effects do not disappear when a person stops taking his or her medication.

Perhaps the most serious side effect of antipsychotic medications is neuroleptic malignant syndrome or NMS, a condition that occurs when someone taking an antipsychotic drug is ill or takes a combination of drugs. People with NMS cannot move or talk. They also have unstable blood pressure and heart rates. Often NMS is fatal. Even when the person recovers, he or she has an 80% chance of experiencing NMS again if given antipsychotic drugs.

Today a new generation of antipsychotics has been developed as a result of recent molecular biology discoveries about how the brain works. These new drugs have fewer side effects. Some do not completely block dopamine receptors; others are more selective, blocking only one type of dopamine receptor. A few of the newer drugs block serotonin or glutamate, two other neurotransmitters.