Child: For sedation before anaesthesia: 2-7 years As alimemazine tartrate: Max: 2 mg/kg, given 1-2 hours before surgery. Dosage recommendations and approved starting ages may vary among countries and between individual products (refer to specific product guidelines).
Oral Pruritus, Urticaria
Adult: As alimemazine tartrate: 10 mg 2 or 3 times daily. For intractable cases: Up to 100 mg daily. Dosage recommendations may vary among countries and between individual products (refer to specific product guidelines). Elderly: As alimemazine tartrate: 10 mg once daily or bid. Dosage recommendations may vary among countries and between individual products (refer to specific product guidelines). Child: >2 years As alimemazine tartrate: 2.5-5 mg 3 or 4 times daily. Dosage recommendations and approved starting ages may vary among countries and between individual products (refer to specific product guidelines).
Renal Impairment
Contraindicated.
Hepatic Impairment
Contraindicated.
Administration
Alimemazine May be taken with or without food.
Contraindications
Epilepsy, Parkinson's disease, phaeochromocytoma, myasthenia gravis, hypothyroidism; history of narrow-angle glaucoma or agranulocytosis; prostatic hypertrophy. Renal and hepatic impairment. Children <2 years.
Special Precautions
Patient with volume depletion, CV disease, hypokalaemia; at risk of seizures (e.g. history of seizures). Children ≥2 years and elderly. Pregnancy and lactation.
Adverse Reactions
Significant: AV block, supraventricular tachycardia, ventricular tachycardia and fibrillation; extrapyramidal effects (e.g. tremor, dystonia, parkinsonism, tardive dyskinesia, akathisia). Blood and lymphatic system disorders: Mild leucopenia. Rarely, agranulocytosis. Endocrine disorders: Hyperprolactinaemia. Eye disorders: Accommodation disorders. Gastrointestinal disorders: Dry mouth, constipation. Hepatobiliary disorders: Jaundice (usually transient). Investigations: ECG changes (e.g. QT interval prolongation, ST segment depression, T or U wave changes). Nervous system disorders: Drowsiness, convulsions, dizziness, headache. Psychiatric disorders: Insomnia, agitation, paradoxical excitement. Renal and urinary disorders: Urinary retention. Respiratory, thoracic and mediastinal disorders: Nasal congestion. Skin and subcutaneous tissue disorders: Rashes; photosensitivity (high-dose use). Vascular disorders: Postural hypotension (particularly in elderly and volume-depleted patients); hypotension, pallor (particularly in children). Potentially Fatal: Neuroleptic malignant syndrome.
Patient Counseling Information
This drug may cause drowsiness, if affected, do not drive or operate machinery. Avoid exposure to sunlight during treatment.
Monitoring Parameters
Monitor mental status. Assess vital signs as clinically indicated.
Overdosage
Symptoms: Drowsiness, hypotension, tachycardia, loss of consciousness, ECG changes, ventricular arrhythmias, hypothermia, severe extrapyramidal dyskinesia, neuroleptic malignant syndrome.
Management: Symptomatic and supportive treatment. May consider performing gastric lavage if the patient presents within 6 hours of ingesting a toxic dose. Administer activated charcoal. In cases of generalised vasodilatation, which may result in circulatory collapse, raising the patient's legs may be sufficient; however, volume expansion with IV fluids may be necessary in severe cases. Positive inotropic agents (e.g. dopamine) may be given if fluid replacement is inadequate to correct circulatory collapse. Avoid using epinephrine. Supraventricular or ventricular tachyarrhythmias may respond to restoration of normal body temperature and correction of metabolic or circulatory disturbances. If arrhythmia is persistent or life-threatening, consider administering antiarrhythmic therapy. Maintain airway or, in extreme circumstances, give assisted respiration for pronounced CNS depression. Administer procyclidine or orphenadrine via IM or IV for severe dystonic reactions. Neuroleptic malignant syndrome may be treated with cooling or dantrolene. IV diazepam may be given in case of convulsions.
Drug Interactions
Additive sedative effect with opioids, barbiturates, anxiolytics, hypnotics and other sedative agents. May enhance the hypotensive effect of antihypertensive agents (particularly α-adrenoreceptor blockers). Increased risk of antimuscarinic adverse effects with antimuscarinic agents. May antagonise the effects of levodopa, clonidine, guanethidine, amphetamine and epinephrine. High-dose alimemazine may reduce the response to hypoglycaemic agents.
Food Interaction
Delayed absorption with food. Additive sedative effect with alcohol.
Action
Description: Mechanism of Action: Alimemazine, a phenothiazine derivative, is an antihistamine with pronounced sedative effects. It also has antimuscarinic, antiemetic, antispasmodic and antiserotonin properties. Synonym(s): Trimeprazine. Pharmacokinetics: Absorption: Food delays absorption. Bioavailability: <70% (tab). Time to peak plasma concentration: 4.5 ± 0.43 hours (tab). Distribution: Plasma protein binding: >90%. Excretion: Elimination half-life: 4.78 ± 0.59 hours.
Chemical Structure
Alimemazine Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 5574, (+-)-Trimeprazine. https://pubchem.ncbi.nlm.nih.gov/compound/Trimeprazine. Accessed Sept. 25, 2025.
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