Thiothixene



Definition

Thiothixene is in a class of drugs called antipsychotics. It is available with a prescription under the generic name of thiothixene or the brand name Navane.

Purpose

Thiothixene is a drug used to treat symptoms of schizophrenia . It is also sometimes used to calm severely agitated people.

Description

Thiothixene has been used in the United States for many years as a treatment for schizophrenia. It is believed to modify the balance of naturally occurring chemicals in the brain called neurotransmitters that regulate the transmission of nerve impulses from cell to cell. The proper balance between neurotransmitters is responsible, in part, for maintaining mental well-being. Thiothixene is thought to alter the balance among neurotransmitters in a way that improves symptoms of schizophrenia.

Thiothixene is available in several different strengths as capsules, as an injection, and as a concentrated liquid form taken by mouth. It is broken down by the liver and eliminated from the body by the kidneys.

Recommended dosage

The dosage of thiothixene varies widely from one individual to another. Initially, 2 mg of thiothixene taken by mouth three times daily is used in milder cases. This dosage may be increased slowly. Fifteen to 30 mg per day is often an effective range.

For more severe cases, 5 mg taken by mouth twice per day is a common starting dosage, with slow increases to 20–30 mg per day. Up to 60 mg of thiothixene may be taken daily. Doses greater than 60 mg per day usually do not provide any additional benefit, but may increase side effects.

Precautions

Thiothixene may alter the rhythm of the heart. As a result, it should not be used by people with a history of irregular or prolonged heart rhythms (long QT syndrome), those with heart failure, or people who have recently had a heart attack. People with other heart conditions should discuss with their physician whether thiothixene is the right antipsychotic drug for them.

Thiothixene may increase the tendency to have seizures . People who have had seizures in the past, including alcohol or drug-induced seizures, should take thiothixene only after discussing the risks and benefits with their physician. People taking thiothixene should call their doctor immediately if they experience any abnormal, involuntary muscle movements, because this adverse effect may be permanent. The risk of abnormal, involuntary muscle movements is believed to increase with long-term use of thiothixene and high dosages.

Thiothixene may increase body temperatures to dangerously high levels. People who exercise strenuously, those exposed to extreme heat, individuals taking drugs with anticholinergic effects (this includes many common antidepressants), and those prone to dehydration, should be alert to increased body temperatures and dehydrationrelated side effects. Fevers, difficulty moving muscles, irregular heartbeats, rapid heartbeats, or excessive sweating are warning signs of possible overheating that should be addressed by a physician immediately.

People taking thiothixene should have regular eye examinations, since use of thiothixene has been associated with abnormalities of the retina, the light-sensitive layer of the eye. Thiothixene may also alter reproductive hormone levels causing irregular menstrual periods, difficulty getting pregnant, enlarged breasts, and breast milk production. Thiothixene can cause enlarged breasts and breast milk secretion in men as well as women. People who have had breast cancer should not take thiothixene unless the benefits of this drug substantially outweigh the risks.

Thiothixene may cause drowsiness. People should not perform hazardous tasks that require mental alertness until they see how the drug affects them. This side effect usually diminishes with continued use of the drug. Thiothixene may make it more difficult to make a patient vomit after a drug overdose or accidental poisoning. Because there is a high incidence of suicide in all patients with psychotic illnesses, people using thiothixene should be observed carefully for signs of suicidal behavior. Women who are pregnant or breast-feeding should not take thiothixene.

Side effects

Common side effects associated with the use of thiothixene are abnormal muscle movements and muscle stiffness, muscle tremors, weight gain, sleepiness, dry mouth, dry eyes, difficulty urinating, constipation, and sudden decreases in blood pressure that cause dizziness when standing up suddenly.

Other side effects that may occur when using thiothixene are headaches, seizures, high blood pressure, rapid heartbeats, blurred vision, liver changes, irregular menstrual periods, abnormal blood cell counts, difficulty breathing, and rash.

Uncommon and serious side effects include neuroleptic malignant syndrome and tardive dyskinesia . Neuroleptic malignant syndrome is an unusual but potentially life-threatening condition. The person with this syndrome becomes extremely rigid, has a high fever, rapid heart rate, and abnormalities on blood tests. The affected person also may have a difficult time breathing and may sweat, and will be admitted to the hospital. Tardive dyskinesia (TD) is a condition that may occur after a long period of using antipsychotic medications. TD is characterized by involuntary movements of the facial muscles and tongue, and may also involve muscles in the trunk or hands or feet. TD may disappear as soon as the medication is stopped, but it may not; if it does not, it is difficult to treat. These potential side effects should be discussed with the patient's doctor.

Interactions

When thiothixene is used with drugs such as bethanechol, propranolol , levodopa, and some antidepressants, some of the side effects associated with thiothixene may increase. Use of narcotic drugs with thiothixene may cause blood pressure to fall to dangerously low levels. If thiothixene is used with levodopa, the actions of levodopa may be diminished.

When thiothixene is used with barbiturates or lithium, thiothixene may be less effective. Because thiothixene may cause sleepiness, it should not be used with other drugs that also cause drowsiness, such as antidepressants, antihistamines, some pain relievers, and alcohol.

Resources

BOOKS

Ellsworth, Allan J., and others. Mosby's Medical Drug Reference. St. Louis, MO: Mosby, Inc, 1999.

Facts and Comparisons Staff. Drug Facts and Comparisons. 6th Edition. St. Louis, MO: Facts and Comparisons,2002.

Mylan Staff. Thiothixene Package Insert. Morgantown, WV: Mylan Pharmaceuticals, Inc, 1998.

Kelly Karpa, RPh, Ph.D.



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