Thioridazine
Mechanism :
It is an antipsychotic agent with the lowest incidence of extrapyramidal side effects among phenothiazine antipsychotics. It is used in the treatment of psychosis, neurosis and behavioural problems in children.
Indication :
Contraindications :
Hypersensitivity to phenothiazines, comatose states, pre-existing CNS depression, severe CVS disorders, uncorrected hypokalaemia or any electrolyte imbalance, known or suspected QT prolongation, history of ventricular arrhythmias including torsades de pointes and porphyria. Bone-marrow suppression, pheochromocytoma, or prolactin-dependent tumours, angle-closure glaucoma, history of jaundice, parkinsonism, DM, hypothyroidism, myasthenia gravis, paralytic ileus, prostatic hyperplasia, or urinary retention. Patients with reduced activity of cytochrome P450 isoenzyme CYP2D6.
Dosing :
2 to 12 years:
Start with 0.5 mg/kg/day orally in 2 to 3 divided doses. May gradually increase up to a maximum of 3 mg/kg/day in divided doses.
13 to 18 years:
Start with 50 to 100 mg orally 3 times a day. May gradually increase to 200 to 800 mg/day in 2 to 4 divided doses.
Precautions:
Due to the risk of life-threatening arrhythmias including torsades de pointes, thioridazine should be used only in patients for whom other antipsychotic drugs have not been effective or tolerable. Before initiating thioridazine, at least 2 other antipsych
Adverse Effect :
Pseudoparkinsonism, tardive dyskinesia, dystonia, orthostatic hypotension, cholestatic jaundice, leukopenia, photosensitivity.
Interaction :
Anticholinergics: Potentiates adverse effects of anticholinergics.
TCAs: Concurrent use of TCAs leads to raised blood levels of both drugs. May antagonise effects of levodopa, bromocriptine and other dopamine agonists. Avoid co-admin with drugs that cause electrolyte imbalance.
Phenytoin: Monitor phenytoin therapy due to inconsistent effects of thioridazine on phenytoin levels.
Hepatic Dose :
Dose may need to be reduced as it undergoes hepatic metabolism.