Uses

Indicated only for management of schizophrenic patients who fail to respond adequately to other antipsychotic drugs due to insufficient effectiveness or intolerable adverse effects, owing to its risk of serious proarrhythmic effects.

Do not use if

Contraindicated with drugs that prolong the QTc interval, in patients with congenital long QT syndrome or history of cardiac arrhythmias, and with CYP2D6 inhibitors such as fluoxetine, paroxetine, or fluvoxamine.

Side effects

Prolongs QTc interval in a dose-dependent manner, increasing risk of life-threatening ventricular arrhythmias such as Torsades de pointes and sudden death. Extrapyramidal symptoms are less common than with other phenothiazines. Sedation, pigmentary retinopathy, and anticholinergic effects may occur.

Warnings

Carries a black-box warning for dose-dependent QTc prolongation and risk of fatal Torsades de pointes. Should be reserved as last-resort therapy for treatment-resistant schizophrenia. Elderly patients with dementia-related psychosis are at increased risk of death.

How it works

Thioridazine is a piperidine phenothiazine that blocks dopamine D2 receptors, producing antipsychotic effects. Unlike other phenothiazines, it causes minimal extrapyramidal stimulation but significantly prolongs cardiac QTc interval by blocking cardiac potassium channels.

Storage

Store at controlled room temperature, protected from light and moisture.