Home Drug Guide Thioridazine

Drug Guide

Generic Name

Thioridazine

Brand Names Mellaril-s

Classification

Therapeutic: Antipsychotic

Pharmacological: Phenothiazine derivative (typical antipsychotic)

FDA Approved Indications

  • Schizophrenia
  • Severe behavioral disorders in psychiatric patients

Mechanism of Action

Thioridazine blocks dopamine D2 receptors in the central nervous system, reducing psychotic symptoms; it also has anticholinergic, antihistaminic, and alpha-adrenergic blocking properties.

Dosage and Administration

Adult: Initial: 50-100 mg twice daily. Dose may be increased gradually based on response and tolerability; usual range: 150-800 mg/day divided into multiple doses.

Pediatric: Not typically recommended due to safety concerns.

Geriatric: Lower initial doses are recommended due to increased sensitivity and risk of side effects.

Renal Impairment: Use caution; no specific adjustment data available, monitor closely.

Hepatic Impairment: Use caution; dose adjustments may be necessary, monitor liver function.

Pharmacokinetics

Absorption: Well absorbed orally.

Distribution: Widely distributed, crosses the blood-brain barrier; about 60-80% protein-bound.

Metabolism: Metabolized mainly in the liver via CYP2D6 and CYP3A4 enzymes.

Excretion: Metabolites excreted in urine and feces.

Half Life: Approximately 20-24 hours, allowing for once or twice daily dosing.

Contraindications

  • Concurrent use of MAO inhibitors
  • Known hypersensitivity to phenothiazines
  • Comgrave cardiac conduction abnormalities (e.g., QT prolongation)

Precautions

  • History of cardiac arrhythmias
  • History of seizure disorders
  • Peripheral circulatory problems
  • Pregnancy category B (use only if clearly needed), lactation: may pass into breast milk
  • Elderly patients with dementia-related psychosis treated with antipsychotics may have increased mortality

Adverse Reactions - Common

  • Sedation (Common)
  • Dizziness (Common)
  • Dry mouth (Common)
  • Blurred vision (Common)
  • Weight gain (Common)

Adverse Reactions - Serious

  • QT prolongation / Torsades de Pointes (Rare)
  • Neuroleptic Malignant Syndrome (Rare)
  • Retinal pigmentation and visual disturbances (Rare)
  • Seizures (Rare)
  • Blood dyscrasias (Rare)

Drug-Drug Interactions

  • Other medications prolonging QT interval (e.g., amiodarone, quinidine)
  • CNS depressants (additive sedation)
  • CYP450 inhibitors or inducers (altering thioridazine levels)

Drug-Food Interactions

  • Alcohol (enhanced sedation and risk of hypotension)

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor cardiac status (ECG) before and during therapy, assess mental status, check for EPS (extrapyramidal symptoms).

Diagnoses:

  • Risk for cardiac arrhythmias
  • Altered mental status
  • Risk for falls

Implementation: Administer with meals to decrease nausea, monitor for side effects, educate patient on avoiding alcohol and driving if sedated.

Evaluation: Assess for reduction in psychotic symptoms, monitor for adverse effects, especially cardiac.

Patient/Family Teaching

  • Take medication exactly as prescribed.
  • Report any signs of dizziness, fainting, or irregular heartbeat.
  • Avoid alcohol and other sedatives.
  • Inform healthcare provider about all other medications.
  • Regular ECG monitoring may be required.

Special Considerations

Black Box Warnings:

  • Increased mortality in elderly patients with dementia-related psychosis.

Genetic Factors: CYP2D6 poor metabolizers may have increased plasma levels, consider dose adjustment.

Lab Test Interference: May cause false-positive results for catecholamine levels.

Overdose Management

Signs/Symptoms: Sedation, hypotension, tachycardia, dry mouth, diffuse ECG changes including QT prolongation, seizures.

Treatment: Supportive care, activated charcoal if early, cardiac monitoring, magnesium sulfate for torsades, advanced cardiac life support as needed.

Storage and Handling

Storage: Store at room temperature, protected from light and moisture.

Stability: Stable for the duration of the labeled expiry date.

🛡️ 5 Critical Medication Safety Tips for Nurses

1

Triple-Check High-Risk Medications

Always have another nurse verify insulin, heparin, warfarin, and chemotherapy drugs. These "high-alert" medications cause the most serious errors. Check concentration, dose calculation, and pump settings twice.

2

Know Look-Alike, Sound-Alike Drugs

Common mix-ups: hydromorphone/morphine, Celebrex/Celexa, Zyprexa/Zyrtec. Always use BOTH generic and brand names, read labels twice, and use barcode scanning when available. One wrong letter can be fatal.

3

Assess Before AND After Giving Meds

Check vitals before cardiac meds, pain levels before analgesics, and blood glucose before insulin. Always reassess within 30 minutes to evaluate effectiveness and watch for adverse reactions.

4

Watch for Drug Interactions

Common dangerous combinations: warfarin + aspirin (bleeding), ACE inhibitors + potassium (hyperkalemia), digoxin + diuretics (toxicity). Always check drug interactions before administering new medications.

5

Educate Your Patients

Teach patients medication names, purposes, major side effects, and what to report. Informed patients catch errors and improve compliance. Always encourage questions - an educated patient is a safer patient.

⚡ Remember: When in doubt, don't give it out! It's always safer to double-check than regret later.

⚠️ Medical Disclaimer

This drug guide is for educational purposes only and is NOT intended for clinical use. Always consult current prescribing information, healthcare providers, and institutional protocols before administering any medication. Do not use this information for patient care decisions.