Prochlorperazin

Prochlorperazine, sometimes spelled prochlorperazin, is a phenothiazine derivative used primarily as an antiemetic and, to a lesser extent, as an antipsychotic. In the body it acts as a dopamine D2 receptor antagonist, with a high affinity for receptors in the chemoreceptor trigger zone and vomiting center. It also has antihistamine and anticholinergic properties that contribute to its sedative and antiemetic effects.

Medical uses: It is employed to relieve nausea and vomiting due to surgery, chemotherapy, and migraines, among other causes. It may be given orally, as a rectal suppository, or by intramuscular or intravenous injection. Onset of antiemetic effects is typically rapid with parenteral administration and slower with oral forms.

Safety and cautions: Prochlorperazine can cause drowsiness, dizziness, and extrapyramidal symptoms such as tremor or rigidity, particularly with prolonged use or in sensitive individuals. Other common effects include dry mouth, blurred vision, and constipation. It can prolong the QT interval and interact with other medications that affect the heart rhythm. It should not be used in individuals with known hypersensitivity to phenothiazines, severe CNS depression, or comatose states, and caution is advised in elderly patients and those with Parkinson disease.

Adverse effects and interactions: Serious but uncommon adverse effects include neuroleptic malignant syndrome and tardive dyskinesia with long-term use. It may interact with alcohol, other central nervous system depressants, and drugs that prolong the QT interval. Brand names include Compazine (United States) and Stemetil (United Kingdom), with generic formulations available in many regions.