Home Drug Guide Methdilazine

Drug Guide

Generic Name

Methdilazine

Brand Names Tacaryl

Classification

Therapeutic: Antipsychotic, Antiemetic

Pharmacological: Phenothiazine derivation, Dopamine antagonist

FDA Approved Indications

  • Nausea and vomiting associated with surgery, anesthesia, or chemotherapy

Mechanism of Action

Methdilazine works primarily by blocking dopamine D2 receptors in the brain, which helps reduce nausea and vomiting. It also exhibits sedative properties due to GABAergic activity and antihistaminic effects.

Dosage and Administration

Adult: Initial dose typically 25-50 mg orally 3-4 times daily; doses may be adjusted based on response and tolerability.

Pediatric: Use is not well established; consult specific pediatric guidelines or a specialist.

Geriatric: Start at lower doses due to increased sensitivity; careful monitoring recommended.

Renal Impairment: Use with caution; no specific dosage adjustment available.

Hepatic Impairment: Use with caution; no specific dosage adjustment available.

Pharmacokinetics

Absorption: Well absorbed from gastrointestinal tract.

Distribution: Widely distributed throughout body tissues, crosses the blood-brain barrier.

Metabolism: Metabolized in the liver.

Excretion: Excreted primarily in urine as metabolites.

Half Life: Approximately 7-10 hours.

Contraindications

  • Hypersensitivity to methdilazine or phenothiazines
  • Severe CNS depression
  • Coma

Precautions

  • Use with caution in patients with history of cardiovascular disease, seizure disorders, or blood dyscrasias. Evaluate closely in elderly patients due to increased risk of sedation and hypotension. Use during pregnancy and lactation only if potential benefit outweighs risks.

Adverse Reactions - Common

  • Sedation (Common)
  • Orthostatic hypotension (Common)
  • Dry mouth (Common)
  • Blurred vision (Common)
  • Dizziness (Common)

Adverse Reactions - Serious

  • Neuroleptic malignant syndrome (Rare)
  • Blood dyscrasias (e.g., leukopenia, agranulocytosis) (Rare)
  • Extrapyramidal symptoms (Rare)
  • Seizures (Rare)

Drug-Drug Interactions

  • Additive CNS depression with alcohol, sedatives, hypnotics
  • Enhancement of hypotensive effects with antihypertensives
  • Potential interactions with other antipsychotics or medications affecting QT interval

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor patient for effectiveness, sedation levels, blood pressure, and signs of extrapyramidal symptoms. Check for baseline cardiac status and blood counts.

Diagnoses:

  • Risk for falls due to sedation or hypotension
  • Altered mental status

Implementation: Administer with food or milk to reduce GI irritation, monitor vitals, observe for adverse effects, and educate patient.

Evaluation: Assess reduction in nausea/vomiting and monitor for adverse effects and safety.

Patient/Family Teaching

  • Take the medication exactly as prescribed.
  • Report any signs of unusual movements, fever, or mental changes.
  • Avoid alcohol and CNS depressants.
  • Change positions slowly to minimize orthostatic hypotension.

Special Considerations

Black Box Warnings:

  • None specifically associated with methdilazine

Genetic Factors: None specified

Lab Test Interference: None known

Overdose Management

Signs/Symptoms: Severe CNS depression, hypotension, extrapyramidal symptoms, coma.

Treatment: Supportive care including stabilization of vitals, activated charcoal if ingestion was recent, and symptomatic treatment. Dialysis is not typically effective.

Storage and Handling

Storage: Store at room temperature away from light and moisture.

Stability: Stable under recommended storage conditions.

This guide is for educational purposes only and is not intended for clinical use.