What is Thioridazine?

Thioridazine is an anti-psychotic drug which is part of a group of medications called phenothiazines. It used to be commonly prescribed for psychotic illnesses such as schizophrenia. Due to concern that large doses of the drug can cause cardiotoxicity, a condition that weakens the heart, or retinopathy, a form of damage to retina of the eye, use of the drug has declined. Now thioridazine is usually only prescribed when other medications have failed to improve a patient’s condition. It has been marketed under the brand names Mellaril® and Mellaril-S®.

The drug contains a mixture of acids and chemicals which can help to address an imbalance of chemicals in the brain. It works to change the way the chemicals in the brain function. As this process can have a dramatic effect on the mind, discontinuation of thioridazine treatment is generally approached with great caution. If the drug is not phased out gradually, a patient can have withdrawal symptoms, which may include insomnia, anxiety, or agitation. In situations where a patient must quickly stop using thioridazine, other drugs may be prescribed to alleviate these symptoms.

Due to the risk of cardiotoxicity and retinopathy, use of thioridazine is for the most part no longer in common use. The manufacturer of Mellaril-S®, which operates in Canada and the United States of America even stopped producing the drug in 2005. Now thioridazine is primarily distributed in generic form.

As there are several known risks to taking thioridazine, patients taking the drug are usually closely observed before, during, and after treatment. The screening process may include several white blood cell counts, therapy, and electrocardiography (ECG) monitoring, which is an examination of electrical activity in the heart. These tests may determine that a patient is not or is no longer eligible for the drug.

There are some conditions which may make taking thioridazine too risky or which require special dosages or observation from the prescribing doctor. Some of these conditions include liver, kidney, or heart disease. A history of breathing problems, such as emphysema or severe asthma, may also be problematic. Other conditions that should be discussed with a doctor include high blood pressure, breast cancer, glaucoma, or Parkinson’s disease.

Minor side effects of taking thioridazine include blurred vision, headache, and dizziness. Patients may also experience drowsiness, insomnia, and anxiety. Sexual problems such as an unusual increase or increase in drive or impotence are also possible. Other potential effects include constipation, itching, and dry mouth.

The more severe side effects of taking thioridazine should receive immediate medical attention. Fainting, fast heartbeat, tremor, and seizures are among the several serious side effects. Patients may also experience fever, confusion, twitching, and joint pain or swelling.