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Prochlorperazine
Systematic (IUPAC) name
2-chloro-10-[3-(4-methyl-1-piperazinyl)propyl]- 10H-phenothiazine
Identifiers
CAS number	58-38-8
ATC code	N05AB04
PubChem	4917
DrugBank	APRD00624
Chemical data
Formula	C20H24ClN3S
Mol. mass	373.943 g/mol
Pharmacokinetic data
Bioavailability	not exactly known, but substantial
Protein binding	91–99%
Metabolism	Mainly hepatic (CYP2D6 and/or CYP3A4)
Half life	4-8 hours, differs with the mode of application
Excretion	Biliary, (colored) inactive metabolites in urine
Therapeutic considerations
Pregnancy cat.	C (Au, U.S.)
Legal status	OTC/POM (UK)
Routes	Oral, buccal, rectal, IM

Prochlorperazine (marketed under the names Compazine, Buccastem, Stemetil, Phenotil) is a drug that belongs to the phenothiazine class of antipsychotic agent that is used for the treatment of nausea and vertigo. It is also a typical antipsychotic drug and a highly potent neuroleptic, 10 to 20 times more potent than chlorpromazine.

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:

1. To alleviate the symptoms of vertigo
2. As an antiemetic, particularly for nausea and vomiting caused by cancer treatment, radiation and in the pre- and postoperative setting
3. Quite recently, in the UK prochlorperazine maleate has been made 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.

Prochlorperazine is available as an oral liquid, tablets, 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).

There is an inhaled form of prochlorperazine under development by Alexza Pharmaceuticals, currently in Phase II clinical trials.

Further information: Typical antipsychotic

Due to the short duration of treatment it is usually well tolerated. It shares in general all side effects of chlorpromazine, but these are seen less frequently so and are less disturbing to the patient, particularly as most patients with the aforementioned conditions are hospitalized. In the treatment of nausea/emesis it might be given together with an antiparkinsonian drug to prevent extrapyramidal side effects of prochlorperazine.

Some individuals are inherently allergic to this medicine. This medicine is known to produce seizures and seizure-like symptoms in individuals who might not have had prior seizures. In such cases, contact health-care facilities for immediate attention. Long-term delays might lead to long-term effects. In extreme cases, it has been known to produce permanent damage to the lower jaw and the jaw joint due to extended seizure symptoms.

If treating psychotic conditions on a long-term basis, the high incidence of early and late (tardive dyskinesia) extrapyramidal side effects should be considered carefully. Prochlorperazine has in the long-term treatment approximately the same incidence and severity of extrapyramidal side effects as haloperidol.

• Prochlorperazine medlineplus.org article
• AZ-001 (Staccato(TM) prochlorperazine) Press release pertaining to phase IIb clinical trial of inhaled prochlorperazine for migraine headache