AHFS Class:

• Antihistamines 56:22.08

Generic Name(s):

• Prochlorperazine

• Prochlorperazine Edisylate

• Prochlorperazine Maleate

Prochlorperazine, a phenothiazine derivative, is an antiemetic.

Prochlorperazine is used for the control of severe nausea and vomiting of various etiologies. The drug is effective for the management of postoperative nausea and vomiting, and that caused by toxins, radiation, or cytotoxic drugs. Prochlorperazine also is effective for the relief of acute migraine attacks and associated nausea and vomiting. (For further information on management and classification of migraine headache, see Vascular Headaches: General Principles in Migraine Therapy, under Uses in Sumatriptan 28:32.28.) Prochlorperazine is not effective in preventing vertigo or motion sickness, or for the management of emesis caused by the action of drugs on the nodose ganglion or locally on the GI tract. Because safety of prochlorperazine for the prevention and treatment of nausea and vomiting associated with pregnancy has not been established, use of the drug is not recommended during pregnancy except in cases of severe nausea and vomiting so serious and intractable that, in the judgment of the clinician, pharmacologic intervention is required and the potential benefits justify the possible risks to the fetus. (See Cautions: Pregnancy, Fertility, and Lactation in the Phenothiazines General Statement 28:16.08.24.)

For the use of prochlorperazine as an antipsychotic agent, see 28:16.08.24.

Administration

Prochlorperazine edisylate is administered orally, by deep IM injection, or by direct IV injection or by IV infusion. When administered by direct IV injection, prochlorperazine is administered at a rate not exceeding 5 mg/minute; the drug should not be given as a bolus injection. Subcutaneous administration of the drug is not recommended because of local irritation. Prochlorperazine maleate is administered orally. Prochlorperazine is administered rectally.

For IV infusion, 20 mg (4 mL) of prochlorperazine injection should be diluted in 1 L of a compatible IV infusion solution (e.g., 0.9% sodium chloride).

Dosage

Dosage of prochlorperazine and its salts is expressed in terms of prochlorperazine. Dosage must be carefully adjusted according to individual requirements and response, using the lowest possible effective dosage. Dosage should be increased more gradually in debilitated, emaciated, or geriatric patients. Since geriatric patients may be more susceptible to hypotension and neuromuscular reactions, these patients should be observed closely; in general, dosages in the lower end of the range are sufficient for most geriatric patients. Since children appear to be more prone to extrapyramidal reactions, even at moderate dosages, they should receive the lowest possible effective dosage and parents should be instructed not to exceed the prescribed dosage.

For the control of severe nausea and vomiting in patients who can tolerate oral administration of the drug, the usual adult oral dosage of prochlorperazine is 5 or 10 mg 3 or 4 times daily. Alternatively, a dosage of 15 mg (as the extended-release Spansule^®) once daily upon arising or 10 mg (as the extended-release Spansule^®) every 12 hours may be used; some patients subsequently may require a dosage of 30 mg (using the appropriate number of 10- or 15-mg extended-release Spansules^®) once daily in the morning. Oral dosages exceeding 40 mg daily should be used only in resistant cases. The usual adult rectal dosage of prochlorperazine for the control of severe nausea and vomiting is 25 mg twice daily. The usual initial adult IM dose of prochlorperazine for the control of severe nausea and vomiting is 5-10 mg. If necessary, the initial IM dose may be repeated every 3 or 4 hours, but total IM dosage should not exceed 40 mg daily. For the control of severe nausea and vomiting, the usual adult IV dose of prochlorperazine is 2.5-10 mg; single IV doses of the drug should not exceed 10 mg and total IV dosage should not exceed 40 mg daily. For the control of severe nausea and vomiting in children older than 2 years of age and weighing more than 9 kg, the usual oral or rectal dosage of prochlorperazine is 0.4 mg/kg or 10 mg/m² daily given in 3 or 4 divided doses. Alternatively, the oral or rectal dosage of prochlorperazine for the control of severe nausea and vomiting in children older than 2 years of age and weighing 9.1-13.2 kg is 2.5 mg once or twice daily, but not exceeding 7.5 mg daily; children weighing 13.6-17.7 kg may receive 2.5 mg 2 or 3 times daily, but no more than 10 mg daily; and children weighing 18.2-38.6 kg may receive 2.5 mg 3 times daily or 5 mg twice daily, but no more than 15 mg daily. Generally, it is not necessary to continue oral or rectal therapy for longer than 24 hours in most pediatric patients. The usual IM dose of prochlorperazine for the control of severe nausea and vomiting in children 2 years of age or older and weighing more than 9 kg is 0.13 mg/kg. Generally, a single IM dose is sufficient to control nausea and vomiting in most pediatric patients.

For the control of severe nausea and vomiting during surgery, the usual initial adult IM dose of prochlorperazine is 5-10 mg given 1-2 hours before induction of anesthesia. If necessary, the initial IM dose may be repeated once, 30 minutes after the initial dose. To control acute symptoms during or after surgery, the usual adult IM dose is 5-10 mg, repeated once in 30 minutes, if necessary. For the control of severe nausea and vomiting during surgery, the usual adult IV dose of prochlorperazine is 5-10 mg given 15-30 minutes before induction of anesthesia. If necessary, the initial IV dose may be repeated once before surgery. To control acute symptoms during or after surgery, the usual adult IV dose is 5-10 mg, repeated once, if necessary; however, single IV doses of the drug should not exceed 10 mg. For the control of severe nausea and vomiting during surgery, prochlorperazine also may be given by IV infusion. For IV infusion, an infusion containing prochlorperazine 20 mg/L is begun 15-30 minutes before induction of anesthesia. Prochlorperazine is not recommended for the control of severe nausea and vomiting during surgery in children.

For further information on chemistry and stability, pharmacology, pharmacokinetics, uses, cautions, acute toxicity, drug interactions, laboratory test interferences, and dosage and administration of prochlorperazine, see the Phenothiazines General Statement 28:16.08.24. For information on the use of prochlorperazine in psychiatric disorders, see 28:16.08.24.

Precautions

Prochlorperazine shares the toxic potentials of other phenothiazines, and the usual precautions of phenothiazine therapy should be observed. (See Cautions in the Phenothiazines General Statement 28:16.08.24.) The incidence of extrapyramidal reactions associated with prochlorperazine therapy appears to be relatively high in hospitalized psychiatric patients and in children.

Care should be taken to avoid skin contact with prochlorperazine edisylate oral solution or injection, since contact dermatitis has occurred rarely.

Pediatric Precautions

Safety and efficacy of prochlorperazine in children younger than 2 years of age or those weighing less than 9 kg have not been established.

Use of prochlorperazine should be avoided in children and adolescents with suspected Reye's syndrome, since the antiemetic and potential extrapyramidal effects produced by the drug may obscure the diagnosis of or be confused with the CNS signs of this condition; the drug also is hepatotoxic.

Prochlorperazine should not be used in children during surgery or in conditions for which pediatric dosage has not been established.

Pharmacology

The precise mechanism of antiemetic action of prochlorperazine is unclear, but the drug inhibits apomorphine-induced vomiting and has been shown to directly affect the medullary chemoreceptor trigger zone (CTZ), apparently by blocking dopamine receptors in the CTZ.

Pharmacokinetics

Following oral administration of prochlorperazine maleate in a tablet formulation, the drug has an onset of action of approximately 30-40 minutes and a duration of action of 3-4 hours. The onset of action following oral administration of prochlorperazine maleate in an extended-release formulation is approximately 30-40 minutes; the duration of action is 10-12 hours. Rectally administered prochlorperazine in a suppository has an onset of action of approximately 60 minutes and a duration of action of approximately 3-4 hours. Following IM administration of prochlorperazine edisylate, the drug has an onset of action within 10-20 minutes and a duration of action of 3-4 hours.

Chemistry and Stability

Chemistry

Prochlorperazine is a phenothiazine antiemetic. The drug is a propylpiperazine derivative of phenothiazine. Prochlorperazine is commercially available as the base, edisylate salt, and maleate salt. Each 7.5 mg of prochlorperazine edisylate or 8 mg of prochlorperazine maleate is approximately equivalent to 5 mg of prochlorperazine.

Prochlorperazine occurs as a clear, pale yellow, viscous liquid and is very slightly soluble in water and freely soluble in alcohol. Prochlorperazine edisylate occurs as a white to very light yellow, odorless, crystalline powder and has approximate solubilities of 500 mg/mL in water and 0.67 mg/mL in alcohol at 25°C. Prochlorperazine maleate occurs as a white to pale yellow, practically odorless, crystalline powder and is practically insoluble in water and has a solubility of approximately 0.83 mg/mL in alcohol at 25°C. Prochlorperazine edisylate injection is a sterile solution of the drug in water for injection. The commercially available injection has a pH of 4.2-6.2 and may contain benzyl alcohol as a preservative and other excipients. The commercially available prochlorperazine edisylate oral solution has a pH of 4.5-5.

Stability

Commercially available preparations of prochlorperazine should be stored in tight, light-resistant containers. Prochlorperazine edisylate oral solutions and injection, and prochlorperazine maleate tablets and extended-release capsules should be stored at a temperature less than 40°C, preferably between 15-30°C; freezing of the oral solutions and injection should be avoided. Prochlorperazine suppositories should be stored at a temperature less than 37°C. Slight yellowish discoloration of the oral solutions or injection will not affect potency or efficacy, but they should not be used if markedly discolored or if a precipitate is present. Prochlorperazine edisylate injection is physically and/or chemically incompatible with some drugs, but the compatibility depends on several factors (e.g., concentrations of the drugs, specific diluents used, resulting pH, temperature). Specialized references should be consulted for specific compatibility information.

Additional Information

The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer's labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.