Thioridazine

What is Thioridazine?

• Thioridazine ((Mellaril or Melleril) is a phenothiazine used to treat the symptoms of schizophrenia.

Thioridazine

Thioridazine molecule ball

Thioridazine3Dan

What are the uses of this medicine?

• Thioridazine (Mellaril or Melleril) is indicated for the management of schizophrenic patients who fail to respond adequately to treatment with other antipsychotic drugs.

Limitations of use:

• Thioridazine can cause a serious type of irregular heartbeat that may cause sudden death.
• There are other medications that can be used to treat your condition that are less likely to cause this life-threatening side effect.
• Therefore, you should not take thioridazine unless you have already been treated with at least 2 other medications for your condition and these medications did not work well or caused side effects that you could not tolerate.

How does this medicine work?

• The basic pharmacological activity of thioridazine is similar to that of other phenothiazines, but is associated with minimal extrapyramidal stimulation.
• Thioridazine hydrochloride The hydrochloride salt form of thioridazine, a piperidine phenothiazine derivative and a dopamine antagonist with antipsychotic property.
• Thioridazine hydrochloride binds to mesolimbic postsynaptic dopamine receptor D2, thereby decreasing dopamine activity leading to decreased psychotic effects, such as hallucinations and delusions.
• In addition, this agent binds to serotonin 5-HT2 receptors, resulting in decreased serotonin activity.

Who Should Not Use this medicine ?

This medicine cannot be used:

• in combination with other drugs that are known to prolong the QTc interval.
• in patients with congenital long QT syndrome or a history of cardiac arrhythmias.
• in severe central nervous system depression or comatose states from any cause including drug induced central nervous system depression.
• in patients with hypertensive or hypotensive heart disease of extreme degree.

What drug interactions can this medicine cause?

• Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Be sure to mention any of the following:

• amiodarone (Cordarone), cisapride (Propulsid) (not available in the US), disopyramide (Norpace), dofetilide (Tikosyn), erythromycin (E.E.S., E-Mycin, Erythrocin), fluoxetine (Prozac, Sarafem), fluvoxamine (Luvox), moxifloxacin (Avelox), paroxetine (Paxil, Pexeva), pimozide (Orap), pindolol (Visken), procainamide, propranolol (Inderal), quinidine, sotalol (Betapace, Betapace AF), and sparfloxacin (Zagam) (not available in the US)
• antidepressants
• antihistamines
• atropine (in Motofen, in Lomotil, in Lonox)
• barbiturates such as pentobarbital (Nembutal), phenobarbital (Luminal), and secobarbital (Seconal)
• epinephrine (Epipen)
• ipratropium (Atrovent)
• medications for anxiety or mental illness, irritable bowel disease, motion sickness, Parkinson's disease, seizures, ulcers, or urinary problems
• narcotic medications for pain
• sedatives
• sleeping pills
• tranquilizers

Is this medicine FDA approved?

• Thioridazine was approved for use in the United States in 1978 and was formerly a commonly prescribed antipsychotic medication, but in recent years has been replaced in large part by the atypical antipsychotics, which have fewer extrapyramidal side effects.
• Use of thioridazine is also restricted because of its propensity to cause prolongation of the QTc interval and increased risk of sudden death.

How should this medicine be used?

Recommended dosage:

• Dosage must be individualized and the smallest effective dosage should be determined for each patient.

Adults:

• The usual starting dose for adult schizophrenic patients is 50 mg to 100 mg three times a day, with a gradual increment to a maximum of 800 mg daily if necessary.
• Once effective control of symptoms has been achieved, the dosage may be reduced gradually to determine the minimum maintenance dose.
• The total daily dosage ranges from 200 mg to 800 mg, divided into two to four doses.

Pediatric Patients:

• For pediatric patients with schizophrenia who are unresponsive to other agents, the recommended initial dose is 0.5 mg/kg/day given in divided doses.
• Dosage may be increased gradually until optimum therapeutic effect is obtained or the maximum dose of 3 mg/kg/day has been reached.

Administration:

• Thioridazine comes as a tablet to take by mouth.
• It is usually taken two to four times a day.
• Take thioridazine at around the same times every day.
• Your doctor will probably start you on a low dose of thioridazine and gradually increase your dose until your symptoms are controlled.
• Once your symptoms have been controlled for some time, your doctor may decrease your dose.

What are the dosage forms and brand names of this medicine?

This medicine is available in fallowing doasage form:

• As tablets for oral administration containing 10 mg, 25 mg, 50 mg or 100 mg.

This medicine is available in fallowing brand namesː Mellaril

What side effects can this medication cause?

The most common side effects of this medicine include:

• drowsiness, dizziness, headache, blurred vision, dry mouth, constipation, tremor, restlessness, muscle spasms and weight gain.

Additional side effects may include:

• Pseudoparkinsonism
• octurnal confusion
• hyperactivity
• lethargy
• psychotic reactions
• nausea
• vomiting
• diarrhea
• nasal stuffiness,
• pallor
• Galactorrhea
• breast engorgement
• amenorrhea
• inhibition of ejaculation
• peripheral edema
• Dermatitis
• skin eruptions of the urticarial type
• Photosensitivity
• prolongation of the QTc interval
• Polymorphic ventricular tachycardia
• Torsades de pointes

What special precautions should I follow?

• Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Thioridazine hydrochloride is not approved for the treatment of patients with dementia-related psychosis.
• 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.
• Tardive dyskinesia, a syndrome consisting of potentially irreversible, involuntary, dyskinetic movements may develop in patients treated with antipsychotic drugs. If signs and symptoms of tardive dyskinesia appear in a patient on antipsychotics, drug discontinuation should be considered. However, some patients may require treatment despite the presence of the syndrome.
• A potentially fatal symptom complex sometimes referred to as Neuroleptic Malignant Syndrome (NMS) has been reported in association with antipsychotic drugs.
• The management of NMS should include, 1) immediate discontinuation of antipsychotic drugs and other drugs not essential to concurrent therapy, 2) intensive symptomatic treatment and medical monitoring, and 3) 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.
• Thioridazine hydrochloride tablets may cause somnolence, postural hypotension, motor and sensory instability, which may lead to falls and, consequently, fractures or other injuries.
• As in the case of other phenothiazines, thioridazine is capable of potentiating central nervous system depressants (e.g., alcohol, anesthetics, barbiturates, narcotics, opiates, other psychoactive drugs, etc.) as well as atropine and phosphorus insecticides.
• Leukopenia and/or agranulocytosis and convulsive seizures have been reported but are infrequent.
• you should know that this medication may make you drowsy and may affect your thinking and movements. Tell your doctor if you plan to drive a car or operate machinery. Your doctor will tell you if these activities are safe for you and may increase the dose of your medication very gradually so that your body can adjust to these side effects.
• Antipsychotic drugs elevate prolactin levels; the elevation persists during chronic administration.
• Ask your doctor about the safe use of alcohol while you are taking thioridazine. Alcohol can make the side effects of thioridazine worse.

What to do in case of emergency/overdose?

Symptoms of overdose may include:

• Cardiovascular: Cardiac arrhythmias, hypotension, shock, ECG changes, increased QT and PR intervals, non-specific ST and T wave changes, bradycardia, sinus tachycardia, atrioventricular block, ventricular tachycardia, ventricular fibrillation, Torsades de pointes, myocardial depression.

• Central Nervous System: Sedation, extrapyramidal effects, confusion, agitation, hypothermia, hyperthermia, restlessness, seizures, areflexia, coma.

• Autonomic Nervous System: Mydriasis, miosis, dry skin, dry mouth, nasal congestion, urinary retention, blurred vision.

• Respiratory: Respiratory depression, apnea, pulmonary edema.

• Gastrointestinal: Hypomotility, constipation, ileus.

• Renal: Oliguria, uremia.

Management of overdosage:

• In case of overdose, call the poison control helpline of your country. In the United States, call 1-800-222-1222.

• Overdose related information is also available online at poisonhelp.org/help.
• In the event that the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services. In the United States, call 911.
• An airway must be established and maintained.
• Adequate oxygenation and ventilation must be ensured.

• Cardiovascular monitoring should commence immediately and should include continuous electrocardiographic monitoring to detect possible arrhythmias.
• Treatment may include one or more of the following therapeutic interventions: correction of electrolyte abnormalities and acid-base balance, lidocaine, phenytoin, isoproterenol, ventricular pacing, and defibrillation.
• Treatment of hypotension may require intravenous fluids and vasopressors. Phenylephrine, levarterenol, or metaraminol are the appropriate pressor agents for use in the management of refractory hypotension.
• Gastric lavage and repeated doses of activated charcoal should be considered. Induction of emesis is less preferable to gastric lavage because of the risk of dystonia and the potential for aspiration of vomitus.
• Acute extrapyramidal symptoms may be treated with diphenhydramine hydrochloride or benztropine mesylate.
• Forced diuresis, hemoperfusion, hemodialysis and manipulation of urine pH are of unlikely benefit in the treatment of phenothiazine overdose.

Can this medicine be used in pregnancy?

• Neonates exposed to antipsychotic drugs, during the third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery.
• Thioridazine hydrochloride should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Can this medicine be used in children?

• Safety and efficacy in children have been established.

What are the active and inactive ingredients in this medicine?

Active Ingredient:

• THIORIDAZINE HYDROCHLORIDE

Inactive Ingredients:

• SILICON DIOXIDE
• CROSCARMELLOSE SODIUM
• FD&C YELLOW NO. 6
• HYDROXYPROPYL CELLULOSE, UNSPECIFIED
• HYPROMELLOSE, UNSPECIFIED
• MAGNESIUM STEARATE
• MICROCRYSTALLINE CELLULOSE
• POLYETHYLENE GLYCOL, UNSPECIFIED
• SODIUM LAURYL SULFATE
• TITANIUM DIOXIDE

Who manufactures and distributes this medicine?

Manufactured for:

• Mylan Pharmaceuticals Inc.
• Morgantown, WV U.S.A.

Manufactured by:

• Mylan Laboratories Limited
• Hyderabad , India

Distributed by:

• Mylan Institutional Inc.
• Rockford, IL U.S.A.

What should I know about storage and disposal of this medication?

• Store at 20° to 25°C (68° to 77°F).
• Protect from light.

Antipsychotic agents

First Generation

• Phenothiazines
  • Chlorpromazine, Fluphenazine, Perphenazine, Prochlorperazine, Thioridazine, Trifluoperazine

• Other
  • Haloperidol, Lithium, Loxapine, Molindone, Pimozide

Second Generation (Atypicals)

• Aripiprazole, Asenapine, Brexpiprazole, Cariprazine, Clozapine, Iloperidone, Lurasidone, Olanzapine, Paliperidone, Pimavanserin, Quetiapine, Risperidone, Ziprasidone

• Dailymed label info on Thioridazine
• FDA Thioridazine

Thioridazine Resources
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