Phenothiazine Antipsychotics

  • Pharmacy Author:
    Omudhome Ogbru, PharmD

    Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

  • Medical and Pharmacy Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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What are phenothiazine antipsychotics?

Phenothiazine antipsychotics are medications used to treat schizophrenia and manifestations of psychotic disorders. Some phenothiazine antipsychotics, like prochlorperazine and chlorpromazine, are used for nausea, vomiting, and hiccups.

Although, the exact mechanism of phenothiazine antipsychotics is unknown, scientists believe that they may work by blocking the action of dopamine in the brain. Dopamine is a neurotransmitter (chemical) that nerves use to communicate with one another. Phenothiazine antipsychotics are used when patients do not respond to other antipsychotics.

What are examples of phenothiazine antipsychotics available in the US?

Examples of phenothiazine antipsychotics are:

What are the side effects of phenothiazine antipsychotics?

There are many side effects of phenothiazine antipsychotics. Common side effects include:

Phenothiazine antipsychotics may cause extra-pyramidal symptoms such:

  • as abnormal muscle contractions,
  • difficulty breathing and swallowing,
  • neck spasms, and
  • movement abnormalities on face, arms, and legs.

Constipation also is common.

Phenothiazine antipsychotics can also cause neuroleptic malignant syndrome (NMS), which include symptoms of:

All phenothiazine antipsychotics carry a boxed warning of increased deaths in elderly patients when used for dementia-related psychosis.

What drugs interact with phenothiazine antipsychotics?

Phenothiazine antipsychotics should not be combined with other antipsychotics or medications that cause extra-pyramidal side effects and neuroleptic malignant syndrome due to an increased likelihood of these side effects.

Phenothiazine antipsychotics should be used with caution with medications (for example, fluoxetine [Prozac, Sarafem, Prozac Weekly]) that reduce the activity of liver enzymes that eliminate phenothiazines because levels of phenothiazines can increase and lead to more side effects.

Phenothiazines affect heart rhythm and the risk of abnormal heart rhythms, especially when they are combined with other drugs that also affect heart rhythm. Examples include:

What formulations of phenothiazine antipsychotics are available?

  • All phenothiazine antipsychotics are available in oral tablet form.
  • Prochlorperazine also is available as a rectal suppository.
  • Fluphenazine and mesoridazine are available as injections.
  • Fluphenazine and mesoridazine are available in oral liquid form.

What about taking phenothiazine antipsychotics during pregnancy or while breastfeeding?

Safe and effective use of phenothiazine antipsychotics during pregnancy has not been established. Newborns exposed to phenothiazine antipsychotics are at risk for extrapyramidal and withdrawal symptoms following delivery. Phenothiazine antipsychotics should only be used if clearly needed when benefits outweigh potential risks to the fetus.

Phenothiazine antipsychotics may enter breast milk; therefore, they should be used with caution in women who are breastfeeding. To avoid potential risks to the newborn, a decision should be made whether to discontinue the drug or to discontinue nursing.

REFERENCE: FDA Prescribing Information.

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Reviewed on 11/18/2014
References
REFERENCE: FDA Prescribing Information.

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