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NERVOUS SYSTEM › PSYCHOLEPTICS › ANTIPSYCHOTICS › Phenothiazines with aliphatic side-chain
levomepromazine
N05AA02
Forms & Strengths
- Tablets: 2 mg, 25 mg, 100 mg
- Oral drops: 40 mg/mL
- Injection solution: 25 mg/mL
Adult Dosing
- Psychosis (oral): Initial 25-50 mg daily in divided doses, titrated up to 100-300 mg daily; up to 1 g daily in severe cases
- Severe chronic pain / Palliative care: 6-25 mg every 4-8 hours orally or subcutaneously
- Agitation / Acute sedation: 10-25 mg intramuscularly, repeated every 4-6 hours as needed
Pediatric Dosing
- Not generally recommended for children under 12 years of age
- Off-label severe agitation/psychosis (adolescents >12 years): Fraction of adult dose based on weight and clinical response under specialist supervision
Indications
- Acute and chronic psychoses, including schizophrenia
- Severe chronic pain, often in palliative care settings
- Severe anxiety, agitation, and restlessness
- Pre- and postoperative sedation
Mechanism of Action
- Low-potency phenothiazine antipsychotic with strong antagonism at central dopamine (D2) and histamine (H1) receptors
- Moderate to high affinity for alpha-1 adrenergic, muscarinic (M1), and serotonin (5-HT2) receptors, contributing to sedative, anticholinergic, and hypotensive effects
Contraindications
- Hypersensitivity to levomepromazine or other phenothiazines
- Severe CNS depression, comatose states
- Circulatory collapse, severe hypotension
- History of QT prolongation, torsades de pointes, or severe cardiac arrhythmias
- Bone marrow depression or history of drug-induced agranulocytosis
- Risk of urinary retention related to urethroprostatic disorders
Adverse Reactions
- Pronounced sedation, somnolence, and lethargy
- Orthostatic hypotension, dizziness, and reflex tachycardia
- Anticholinergic effects: dry mouth, constipation, blurred vision, urinary retention
- Extrapyramidal symptoms (less frequent than high-potency agents, but akathisia, dystonia, and tardive dyskinesia can occur)
- QT interval prolongation, ECG changes, arrhythmias
- Weight gain, hyperprolactinemia, sexual dysfunction
- Rare: Neuroleptic Malignant Syndrome (NMS), agranulocytosis
Drug Interactions
- CNS depressants (opioids, sedatives, alcohol, barbiturates): potentiation of sedative and respiratory-depressant effects
- Drugs prolonging the QT interval (antiarrhythmics, certain antibiotics, other antipsychotics): increased risk of ventricular arrhythmias
- Antihypertensive agents: enhanced hypotensive effect, risk of severe orthostasis
- Anticholinergic drugs: additive anticholinergic toxicity (paralytic ileus, acute glaucoma)
- CYP2D6 inhibitors: may increase levomepromazine plasma concentrations
Curated Content: Needs Vetting Before Put to Clinical Use