Thioridazine

Thioridazine is a prescription medication used to treat schizophrenia. Thioridazine belongs to a group of drugs called antipsychotics, which work by changing the activity of certain natural substances in the brain.

This medication comes in tablet form and is typically taken 2 to 4 times a day, with or without food.

Common side effects of thioridazine include dry mouth, blurry vision, constipation, nausea, vomiting, diarrhea, and drowsiness. Do not drive or operate heavy machinery until you know how thioridazine affects you.

CYP2D6 is a protein in your body that is involved in the elimination of thioridazine and other drugs from your body. Some patients have less of this protein in their bodies, affecting how much of the drug gets eliminated. Levels of CYP2D6 can vary greatly between individuals, and those having less of this protein are known as "poor metabolizers." 

CYP2D6 testing is done to determine whether you are a poor metabolizer. If you are a poor metabolizer, the levels of thioridazine in your blood can become too high. As a result you may be at an increased risk of having more side effects from thioridazine. 

Your doctor may adjust your dose of thioridazine if you are a poor metabolizer.

Thioridazine is a prescription medication used to treat schizophrenia who fail to respond adequately to treatment with other antipsychotic drugs.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Thioridazine may be found in some form under the following brand names:

• Mellaril

• Mellaril-S

Serious side effects have been reported with thioridazine. See the “Drug Precautions” section.

Common side effects of thioridazine include the following:

• dry mouth
• blurry vision
• constipation
• nausea
• vomiting
• diarrhea
• drowsiness
• uncontrolled muscle movement

This is not a complete list of thioridazine side effects. Ask your doctor or pharmacist for more information.

Tell your doctor if you have any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Tell your doctor about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

• Medications that block a protein in the body (CYP2D6) such as quinidine (Qualaquin), fluoxetine (Prozac, Sarafem), amitriptyline (Elavil, Amitril), and paroxetine (Paxil)
• Drugs that can cause an arrhythmia called Torsades des Pointes such as
  • certain anti-arrhythmia medications including procainamide, sotalol (Betapace), quinidine, dofetilide (Tikosyn), amiodarone (Nexterone, Pacerone, Cordarone), ibutilide (Corvert)
  • certain fluoroquinolone antibiotics including levofloxacin (Levaquin), ciprofloxacin (Cipro), gatifloxacin (Zymar), moxifloxacin (Avelox)
  • certain macrolide antibiotics including clarithromycin (Biaxin), erythromycin (EES, others)
  • certain azole antifungals including ketoconazole (Nizoral), itraconazole (Sporanox, Onmel)
  • certain antidepressants including amitriptyline, desipramine (Norpramin), imipramine (Tofranil), doxepin (Silenor), fluoxetine (Prozac, Sarafem), sertraline (Zoloft), venlafaxine (Effexor XR)
  • certain antipsychotics including haloperidol (Haldol), droperidol (Inapsine), quetiapine (Seroquel XR), thioridazine, ziprasidone (Geodon)
  • and other medications including sumatriptan (Treximet, Imitrex, Alsuma, Zecuity), zolmitriptan (Zomig), dolasetron (Anzemet), and methadone (Methadone, Dolophine)
• Fluvoxamine (Luvox)
• Propranolol (Hemangeol, Inderal, InnoPran XL)
• Pindolol

This is not a complete list of drug interactions. Ask your doctor or pharmacist for more information.

Serious side effects have been reported with thioridazine including the following:

• QT prolongation. This is a condition when changes in the electrical activity of your heart occur, causing irregular heartbeats that can be life threatening. Talk to your healthcare provider about other medicines you are taking before you start taking thioridazine. Tell your healthcare provider right away if you have any signs or symptoms of QT prolongation:
  • feeling faint
  • lightheadedness
  • dizziness
  • feeling like your heart is beating irregularly or quickly
• Tardive Dyskinesia. This is a condition that causes the body to move involuntarily (twitching). It mostly tends to affect the mouth and lower part of the face. Tell your healthcare provider right away if you have any signs or symptoms of tardive dyskinesia:
  • finger movements or twitching
  • involuntary movements, or twitching of the mouth
  • constantly sticking out the tongue, or tongue thrusting
  • repetitive chewing
  • swinging of the jaw
• Neuroleptic Malignant Syndrome (NMS). NMS is a life-threatening condition that is can be caused by side effects to drugs that work in the brain. Tell your healthcare provider right away if you have any signs or symptoms of NMS:
  • high fevers
  • sweating
  • fluctuating blood pressure
  • confusion
  • having rigid or stiff muscles
• Low white blood cell count. Your white blood cells are responsible for protecting the body from infections. Tell your healthcare provider right away if you have any signs or symptoms of having a low white blood cell count:
  • Getting infections easily
  • Fever
  • Sore throat
  • Severe chills
• Seizures

Thioridazine can cause drowsiness. Do not drive or operate heavy machinery until you know how thioridazine affects you.

Do not take thioridazine if you:

• are allergic to thioridazine or to any of its ingredients
• take drugs that can cause an arrhythmia called Torsades des Pointes
• take medications that block a protein in the body (CYP2D6) such as quinidine (Qualaquin), fluoxetine (Prozac, Sarafem), amitriptyline (Elavil, Amitril), and paroxetine (Paxil)
• take medications that severely reduce alertness, or are in a coma
• have very high blood pressure, or have very low blood pressure

Medications can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of thioridazine, there are no specific foods that you must exclude from your diet when receiving this medication.

Before taking thioridazine, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

• are allergic to thioridazine or to any of its ingredients
• are taking medications that severely reduce your mental alertness
• are taking other anti-psychotic medications
• have, or have had, problems with your white blood cells
• have, or have had, breast cancer
• have problems with blood pressure
• are pregnant or breastfeeding

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

Tell your doctor if you are pregnant or plan to become pregnant.

It has been shown that use of thioridazine in pregnant women caused some babies to be born with problems. However, in some serious situations, the benefit of using this medication may be greater than the risk of harm to the baby.

Tell your doctor if you are breastfeeding or plan to breastfeed.

It is not known if thioridazine crosses into human milk. Because many medications can cross into human milk and because of the possibility for serious adverse reactions in nursing infants with use of this medication, a choice should be made whether to stop nursing or stop the use of this medication. Your doctor and you will decide if the benefits outweigh the risk of using thioridazine.

Take thioridazine exactly as prescribed.

This medication comes in tablet form and is typically taken 2 to 4 times a day, with or without food.

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

• The dose your doctor recommends may be based on the following:
• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• your weight
• your height
• your age
• your gender

The usual starting dose for thioridazine is 50 mg to 100 mg 3 times a day. The maximum dose should be 200 mg 4 times a day, or 400 mg 2 times a day. 

If you take too much thioridazine, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

If thioridazine is administered by a healthcare provider in a medical setting, it is unlikely that an overdose will occur. However, if overdose is suspected, seek emergency medical attention.

• Store thioridazine at room temperature
• Keep this and all medicines out of the reach of children.
• Protect this medication from light

Thioridazine has been shown to prolong the QTc interval in a dose related manner, and drugs with this potential, including thioridazine, have been associated with Torsades de pointes type arrhythmias and sudden death. Due to its potential for significant, possibly life threatening, proarrhythmic effects, thioridazine should be reserved for use in the treatment of schizophrenic patients who fail to show an acceptable response to adequate courses of treatment with other antipsychotic drugs, either because of insufficient effectiveness or the inability to achieve an effective dose due to intolerable adverse effects from those drugs.

Increased Mortality in Elderly Patients with Dementia-Related Psychosis

Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Analyses of seventeen placebo-controlled trials (modal duration of 10 weeks), largely in patients taking atypical antipsychotic drugs, revealed a risk of death in drug-treated patients of between 1.6 to 1.7 times the risk of death in placebo-treated patients. Over the course of a typical 10-week controlled trial, the rate of death in drug-treated patients was about 4.5%, compared to a rate of about 2.6% in the placebo group. Although the causes of death were varied, most of the deaths appeared to be either cardiovascular (e.g., heart failure, sudden death) or infectious (e.g., pneumonia) in nature. Observational studies suggest that, similar to atypical antipsychotic drugs, treatment with conventional antipsychotic drugs may increase mortality. The extent to which the findings of increased mortality in observational studies may be attributed to the antipsychotic drug as opposed to some characteristic(s) of the patients is not clear. Thioridazine hydrochloride is not approved for the treatment of patients with dementia-related psychosis.