Nurses Compass
Drug Guide
Methdilazine
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/ADrug-Herb Interactions
N/ANursing 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.