Phenothiazine Antipsychotics (cont.)

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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.

Medically Reviewed by a Doctor on 11/18/2014

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