Chlorpromazin

Chlorpromazin, or chlorpromazine, is a phenothiazine antipsychotic medication used to treat schizophrenia and other psychoses, as well as severe agitation and nausea in some settings. It was one of the first antipsychotic drugs to be used clinically and helped transform modern psychiatry.

Mechanism of action: Chlorpromazin primarily blocks dopamine D2 receptors in the brain, reducing psychotic symptoms. It also antagonizes several other receptors, including histamine H1, alpha-adrenergic, and muscarinic receptors, contributing to sedation and a range of adverse effects.

Medical uses: Indicated for schizophrenia and manic states, short-term treatment of severe agitation in psychosis, and as an antiemetic in certain surgical settings. It has also historically been used to treat intractable hiccups.

Administration and pharmacokinetics: Available in oral forms (tablets, syrup) and parenteral formulations (standard intramuscular or intravenous injections for acute agitation, and long-acting formulations in some cases). It is metabolized in the liver and eliminated mainly by renal and hepatic routes. Onset and duration depend on the route of administration; plasma levels can be influenced by liver function and drug interactions.

Adverse effects and safety: Common effects include drowsiness, dizziness, and low blood pressure. Extrapyramidal symptoms such as tremor, rigidity, and akathisia, as well as tardive dyskinesia with prolonged use, may occur. Anticholinergic effects (dry mouth, constipation), weight gain, and sedation are also observed. Photosensitivity and rare blood dyscrasias can occur. It may prolong the QT interval and interact with other sedatives. Use is cautioned in elderly patients with dementia-related psychosis and in several other medical conditions.

History: Chlorpromazin was developed in the 1950s by scientists at Rhône-Poulenc and introduced for psychiatric use in the early 1950s, marking the start of the era of neuroleptics.