pathology Management of NMS should include, immediate discontinuation of antipsychotic drugs and other drugs not essential to concurrent therapy, intensive symptomatic treatment and medical monitoring, and treatment of any concomitant serious medical problems for which specific treatments are available; there is no general agreement about specific pharmacological treatment regimens for uncomplicated NMS If patient requires antipsychotic drug treatment after recovery from NMS, potential reintroduction of drug therapy should be carefully considered; the patient should be carefully monitored, since recurrences of NMS have been reported Drug interaction overview Drugs that inhibit cytochrome P450 2D6 isozyme activity (eg, fluoxetine and paroxetine), and certain other drugs (eg, fluvoxamine, propranolol, and pindolol) appear to appreciably inhibit metabolism of this drug; the resulting elevated levels of the drug would be expected to augment the prolongation of the QTc interval associated with thioridazine and may increase risk of serious, potentially fatal, cardiac arrhythmias, such as Torsades de pointes type arrhythmias Such an increased risk may result also from additive effect of coadministering this drug with other agents that prolong the QTc interval; therefore, thioridazine is contraindicated with these drugs as well as in patients, comprising about 7% of the normal population, who are known to have a genetic defect leading to reduced levels of activity of P450 2D6 Pregnancy Use during pregnancy only if potential benefit justifies potential risk to fetus Neonates exposed to antipsychotic drugs, during third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery; there have been reports of agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress and feeding disorder; these complications have varied in severity; while in some cases symptoms have been self-limited, in other cases neonates have required intensive care unit support and prolonged hospitalization Lactation Not known whether the drug is present in the milk; infants exposed to antipsychotic agents should be monitored for signs of adverse effects; routine monitoring of infant serum concentrations not recommendedPregnancy Categories A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk. B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available. Mechanism of Action Piperazine phenothiazine agent; antagonist for the postsynaptic mesolimbic dopaminergic D2 receptors in the brain; decreases the release of hypothalamic and hypophyseal hormones Pharmacokinetics Half-Life elimination: 24 hr Metabolism: Hepatic P450 enzyme CYP2D6 Enzymes inhibited: CYP2D6 Protein bound: 95% Duration: 4-5 days BRAND FORM. UNIT PRICE PILL IMAGE thioridazine oral- 100 mg tabletthioridazine oral- 25 mg tabletthioridazine oral- 10 mg tabletthioridazine oral- 50 mg tabletthioridazine oral- 50 mg tabletthioridazine oral- 25 mg tabletthioridazine oral- 10 mg tabletthioridazine oral- 100 mg tabletCopyright © 2010 First DataBank, Inc.Print Patient Educationthioridazine oral THIORIDAZINE - ORAL (thigh-oh-RID-uh-zeen) COMMON BRAND NAME(S): Mellaril WARNING: Thioridazine rarely has caused very serious (possibly fatal) irregular heartbeat (QT prolongation in the EKG). It should be used only in patients who have not shown improvement with at least 2 other antipsychotic medications or who cannot tolerate other antipsychotic medications. This medication should not be used with other medications that can also cause a slow or irregular heartbeat. (See also Drug Interactions.)There may be a slightly increased risk of serious, possibly fatal side effects (such as heart failure, fast/irregular heartbeat, pneumonia) when this medication is used by older adults with dementia. This medication is not approved for the treatment of dementia-related behavior problems. Discuss the risks and benefits of this medication, as well as other effective and possibly safer treatments for dementia-related behavior problems, with the doctor. USES: This medication is used to treat certain mental/mood disorders (such as schizophrenia). This medication helps you to think more clearly, feel less nervous, and take part in everyday life. It can also help prevent suicide in people likely to harm themselves and reduce aggression and the desire to hurt others. It can help decrease your negative thoughts and hallucinations. Thioridazine belongs to a class of drugs known as phenothiazines. HOW TO USE: Take this medication by mouth with or without food as directed by your doctor, usually 2 to 4 times a day.Dosage is based on your medical condition and response to therapy. Once your condition improves and you are better for a while, your doctor may work with you to reduce your regular dose. This may be done over time. Do not stop your medication or lower your dose without talking with your doctor first. Some conditions may become worse when the drug is stopped abruptly. Your dose may need to be gradually reduced.Use this medication regularly in order to get the most benefit from it. To help you remember, use it at the same times each day.Tell your doctor if your condition lasts or gets worse. SIDE EFFECTS: Dizziness, lightheadedness, drowsiness, difficulty urinating, constipation, restlessness, headache, and blurred vision may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Dizziness and lightheadedness can increase the risk of falling. Get up slowly when rising from a sitting or lying position.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor right away if you have any serious side effects, including: shakiness (tremors), mask-like facial expression, jerking movements while walking, signs of infection (such as sore throat that doesn't go away, fever), vision changes (such as vision loss, sudden difficulty seeing at night, brown-tinged vision).Get medical help right away if you have any very serious side effects, including: severe dizziness, fainting, slow heartbeat, seizures.Thioridazine may rarely cause a condition known as tardive dyskinesia. In some cases this condition may be permanent. Tell your doctor right away if you develop any unusual/uncontrolled movements (especially of the face, lips, tongue, arms or legs).In rare cases, thioridazine may increase your level of a certain chemical made by the body (prolactin). For females, this increase in prolactin may result in unwanted breast milk, missed/stopped periods, or difficulty becoming pregnant. For males, it may result in decreased sexual ability, inability to produce sperm, or enlarged breasts. If you develop any of these symptoms, tell your doctor right away.This medication may rarely cause a very serious condition called neuroleptic malignant syndrome (NMS). Get medical help right away if you have any of the following symptoms: fever, muscle stiffness/pain/tenderness/weakness, severe tiredness, severe confusion, sweating, fast/irregular heartbeat, dark urine, signs of kidney problems (such as change in the amount of urine).A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345. PRECAUTIONS: Before taking thioridazine, tell your doctor or pharmacist if you are allergic to it; or to other phenothiazines (such as chlorpromazine); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: nervous system problems (such as seizures, drug/alcohol overdose, severe drowsiness), blood pressure problems, certain blood problems (such as low white blood cell count), Parkinson's disease, low enzymes needed to remove drugs from the body (slow hydroxylator).Thioridazine may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using thioridazine, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using thioridazine safely.This drug may make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness.Older adults may be more sensitive to the side effects of this drug, especially dizziness, lightheadedness, drowsiness, confusion, constipation, difficulty urinating, and QT prolongation (see above). Dizziness, lightheadedness, drowsiness, and confusion can increase the risk of falling.During pregnancy, this medication should be used only when clearly needed. Babies born to mothers who have used this drug during the last 3 months of pregnancy may rarely develop symptoms including muscle stiffness or shakiness, drowsiness, feeding/breathing difficulties, or constant crying. If you notice any of these symptoms in your newborn especially during their first month, tell the doctor right away.Since untreated mental/mood problems (such as schizophrenia, depression) can be a serious condition, do not stop taking this medication unless directed by your doctor. If you are planning pregnancy, become pregnant, or think you may be pregnant, immediately discuss with your doctor the benefits and risks of using this medication during pregnancy.It is unknown if this drug passes into breast milk. Consult your doctor before breast-feeding. DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug include: cabergoline, elacestrant, lithium, certain products used to treat chronic hepatitis C (asunaprevir, ombitasvir/paritaprevir/ritonavir), medications for Parkinson's disease (such as levodopa).Many drugs besides thioridazine may affect the heart rhythm (QT prolongation), including amiodarone, dofetilide, pimozide, procainamide, quinidine, sotalol, macrolide antibiotics (such as erythromycin), ziprasidone, among others. Before using thioridazine, report all medications you are currently using to your doctor or pharmacist.Other medications can affect the removal of thioridazine from your body, which may affect how thioridazine works. Examples include bupropion, cinacalcet, dacomitinib, duloxetine, mirabegron, pindolol, propranolol, rolapitant, terbinafine, certain SSRI antidepressants (such as fluoxetine, fluvoxamine, paroxetine), among others.Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely. OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away.