Prochlorperazine is a phenothiazine drug. Most drugs in this category are used as anti-psychotics (neuroleptics). Neuroleptic means "nerve seizing", and describes the semi-paralyzing effect these drugs have on the brain and nervous system. Stemetil is no longer being manufactured for sale in Canada as an anti-psychotic, but it is still available for treatment of nausea.
It is now relatively seldom used for the treatment of psychosis and the manic phase of bipolar disorder. It has a prominent antiemetic/antivertiginoic activity and is most often used for the (short-time) treatment of nausea and vomiting and vertigo as follows:
In the UK, prochlorperazine maleate is available as Buccastem M in buccal form as an over-the-counter treatment for migraine. In this indication it blocks the chemoreceptor trigger zone (CTZ) in the brain, which is responsible for causing severe nausea and vomiting. Its OTC use is strictly restricted to a maximum of 2 days, because of the potentially severe side effects of prochlorperazine, which mandate supervision by a health care provider.
In the UK prochlorperazine maleate has been prescribed to alleviate the symptoms of labyrinthitis, which include not only nausea and vertigo, but spatial and temporal 'jerking' and distortion
Prochlorperazine is thought to exert its antipsychotic effects by blocking dopamine receptors.
Prochlorperazine is analogous to chlorpromazine, both of these agents antagonize dopaminergic D2 receptors in various pathways of the central nervous system. This D2 blockade results in antipsychotic, antiemetic and other effects. Hyperprolactinaemia is a side effect of dopamine antagonists as blockade of D2 receptors within the tuberoinfundibular pathway results in increased plasma levels of prolactin.
Formulations and pharmacokinetics
5mg oral tablet of Prochlorperazine
Prochlorperazine is available as an oral liquid, tablets, cream for trans dermal (compounding pharmacy), and suppositories, as well as in an injectable form.
Following intramuscular injection the antiemetic action is evident within 5 to 10 minutes and lasts for 3 to 4 hours. Rapid action is also noted after buccal treatment. With oral dosing the start of action is delayed but the duration somewhat longer (approximately 6 hours).
It is available in Egypt under the brand name Emedrotec buccal adhesive tablets by Eva pharma.
There is an inhaled form of prochlorperazine under development by Alexza Pharmaceuticals, currently[when?] in Phase II clinical trials.
Prochlorperazine can also cause a life-threatening condition called neuroleptic malignant syndrome (NMS). Some symptoms of NMS include: A high fever, stiff muscles, confusion, irregular pulse or blood pressure, a fast heart rate (tachycardia), sweating, irregular heart rhythms (arrhythmias). VA and FDA research shows injection site reaction.
Prochlorpherazine (2-chloro-10-[3-(4-methyl-1-piperazinyl) propyl]-phenothiazine) is prepared by the alkylation of 2-chlorophenothiazine using 4-methyl-1-piperazinyl)propyl-3-chloride in the presence of sodamide, or alkylation of 2-chloro-10-[(3-chloropropyl)]phenothiazine using 1-methylpiperazine.
^Casey JF, Lasky JJ, Klett CJ, Hollister LE (August 1960). "Treatment of schizophrenic reactions with phenothiazine derivatives. A comparative study of chlorpromazine, triflupromazine, mepazine, prochlorperazine, perphenazine, and phenobarbital". American Journal of Psychiatry117: 97–105. doi:10.1176/appi.ajp.117.2.97 (inactive 2010-03-18). PMID13808146.
^Benson AJ (June 1969). "Effect of diphenidol and prochlorperazine on semicircular canal function in man". Aerospace Medicine40 (6): 589–95. PMID4891872.
^Brown, Thomas Markham; Stoudemire, Alan (1998). "Antipsychotics". Psychiatric Side Effects of Prescription and Over-The-Counter Medications. American Psychiatric Publishing. p. 1946. Retrieved 2013-01-18.