Prochlorperazine Edisylate

Introduction Overview

Generic Name

prochlorperazine edisylate

Brand Name

Compazine, Compro

Dosage Form

injectable solution for intramuscular or intravenous administration (5 mg/mL)

Drug Class

Phenothiazine antiemetics, Phenothiazine antipsychotics

Pharmacokinetics

Absorption:
Prochlorperazine edisylate injection is administered parenterally, primarily via intramuscular or intravenous routes, bypassing the gastrointestinal tract, thus providing rapid and reliable systemic absorption. Upon intramuscular administration, onset of action occurs within 10 to 20 minutes, providing a prompt therapeutic effect, particularly useful in acute management of severe nausea and vomiting. The bioavailability following IM injection is effectively complete as the medication directly enters systemic circulation. Clinical studies demonstrate a duration of action approximately 3 to 4 hours post-injection. Factors such as injection site perfusion and patient muscle mass may influence absorption rate. Subcutaneous administration is contraindicated due to local irritation and poor systemic absorption.

Distribution:
Prochlorperazine exhibits extensive distribution to body tissues after parenteral administration. As a lipophilic phenothiazine derivative, it crosses lipid membranes efficiently. It binds variably to plasma proteins, primarily albumin, which influences its free active concentration. It also crosses the blood-brain barrier, exerting central nervous system effects by acting on dopaminergic pathways, critical in its antipsychotic and antiemetic activities. Volume of distribution is moderately high, reflecting tissue penetration. Distribution to the fetal compartment and breast milk has been documented, warranting caution in pregnancy and nursing.

Metabolism:
Prochlorperazine undergoes extensive hepatic metabolism primarily via the cytochrome P450 enzyme system, including CYP2D6 and CYP3A4 isoforms. It is biotransformed into multiple inactive metabolites through oxidative deamination, hydroxylation, and conjugation pathways. Hepatic impairment may alter drug clearance, necessitating careful dosing in patients with liver dysfunction. Phenothiazines, including prochlorperazine, may interact with inducers or inhibitors of cytochrome enzymes, affecting plasma levels and clinical responses.

Elimination:
Metabolites of prochlorperazine are primarily excreted renally, with minor biliary excretion. The elimination half-life is dose-dependent but generally ranges from 6 to 8 hours, permitting dosing intervals consistent with its duration of clinical effect. Renal impairment may affect elimination, requiring dose adjustment. Phenothiazines are not significantly removed by dialysis due to extensive tissue binding. The drug's elimination profile supports its use for acute symptoms yet informs caution in chronic administration to minimize accumulation and toxicity.

Dosage Forms

Available Dosage Forms:
Prochlorperazine is available as a sterile injectable solution for intramuscular or intravenous use. The commercial preparation is prochlorperazine edisylate injection at a concentration of 5 mg/mL, supplied in 2 mL vials delivering 10 mg per vial. This injectable form is intended exclusively for deep intramuscular or slow intravenous administration; subcutaneous use is contraindicated due to local irritation.

Dosages for Adults and Adolescents:
- Severe Nausea and Vomiting: Initial intramuscular dose of 5 mg to 10 mg (1–2 mL), repeated every 3 to 4 hours as necessary; maximum daily intramuscular dose not to exceed 40 mg.
- Intravenous administration: 2.5 mg to 10 mg (0.5–2 mL) by slow injection or infusion at a rate not exceeding 5 mg per minute, repeatable, with a maximum daily dose of 40 mg. Bolus injection is discouraged to minimize risk of hypotension.
- Adult Surgery (for nausea and vomiting): IM 5 to 10 mg 1 to 2 hours before anesthesia induction, repeat once in 30 minutes if needed. IV 5 to 10 mg 15 to 30 minutes before anesthesia, single repeat if required, with cautious administration.
- Psychiatric Disorders (Schizophrenia): IM 10 to 20 mg (2–4 mL) for immediate control; repeat every 2 to 4 hours (or hourly in resistant cases) up to 3–4 doses, then switched to oral administration if possible.

Specific Patient Populations:
- Elderly: Lower starting doses are recommended due to increased sensitivity, particularly regarding hypotension and neuromuscular side effects; dose titration should be gradual with careful monitoring.
- Children: Not recommended for use in pediatric surgery or in children weighing under 20 pounds or aged under 2 years. Pediatric dosing for severe nausea and vomiting is 0.06 mg/lb body weight intramuscularly. Children are at increased risk for extrapyramidal side effects and require close supervision.
- Patients with hepatic or renal impairment require cautious dosing and monitoring, although detailed pharmacokinetic adjustments are not well-defined due to limited data.

Storage and Handling:
- Protect injection vials from light, maintaining at controlled room temperature 20º–25ºC (68º–77ºF), allowing excursions.
- Discard solution if markedly discolored.

Mechanism Of Action

Prochlorperazine is a phenothiazine derivative pharmacologically classified as both an antiemetic and an antipsychotic agent. Its primary molecular mechanism involves antagonism of dopamine receptors, predominantly the D2 subtype, within the central nervous system. By blocking D2 receptors in the chemoreceptor trigger zone of the medulla oblongata, prochlorperazine inhibits signals that provoke nausea and vomiting, thereby exerting potent antiemetic effects.

At the cellular level, prochlorperazine’s blockade of dopamine receptors decreases dopaminergic neurotransmission, which plays a central role in psychotic symptoms, including hallucinations and delusions. This dopaminergic blockade within mesolimbic and mesocortical pathways underlies its antipsychotic efficacy in controlling schizophrenia and other psychotic disorders. Additionally, prochlorperazine exhibits some affinity for other receptor types, including alpha-adrenergic and muscarinic receptors, contributing to its side effect profile.

Biochemically, the drug's binding inhibits the post-synaptic dopamine receptors, attenuating dopaminergic overactivity implicated in psychosis and emesis. This interaction stabilizes neuronal activity and reduces aberrant neurotransmitter signaling responsible for nausea and psychotic manifestations. Furthermore, prochlorperazine’s alpha-adrenergic blockade can cause peripheral vasodilation, which explains some of its adverse hypotensive effects clinically observed.

Comparatively, prochlorperazine shares mechanisms with other phenothiazines like chlorpromazine but is more specifically utilized for antiemetic and psychiatric indications. Research evidence from clinical trials supports its rapid onset of action after parenteral administration and efficacy in severe nausea control and schizophrenia symptom management. Long-term use, however, is tempered by risks such as tardive dyskinesia, underpinning the need for judicious clinical use supported by ongoing assessments.

Pharmacological Actions

Dopamine D2 receptor antagonism resulting in antiemetic and antipsychotic effects.
Pronounced depressant action on the chemoreceptor trigger zone of the medulla to control nausea and vomiting.
Alpha-adrenergic receptor blockade contributing to vasodilation and possible hypotension.
Extrapyramidal symptom induction via dopamine blockade in the nigrostriatal pathway.
Central nervous system depressant effects including sedation and motor restlessness.
Potential prolactin elevation due to tuberoinfundibular dopamine antagonism.
Anticholinergic effects due to muscarinic receptor activity (though comparatively mild).
Reduction of dopaminergic neurotransmission in mesolimbic and mesocortical regions controlling psychosis.
Potential to cause neuroleptic malignant syndrome as a rare but serious pharmacological effect.
Interference with thermoregulatory mechanisms under extreme heat conditions.
Interaction with central nervous system depressants leading to enhanced sedative effects.
Modulation of autonomic nervous system via multiple receptor activities causing side effects such as dry mouth and urinary retention.

Therapeutic Or Clinical Uses

Management of severe nausea and vomiting due to various etiologies including postoperative states.
Control of psychotic disorders, particularly schizophrenia, as an antipsychotic agent.
Treatment of persistent nausea and vomiting that are refractory to other antiemetics.
Adjunct in adult surgical procedures to prevent and control perioperative nausea and vomiting.
Symptomatic treatment in migraine-associated nausea (off-label use).
Use in chemotherapy-induced nausea and vomiting relief in certain cases.
Management of vertigo associated with inner ear disorders (off-label use).
Suppressing emesis in gastrointestinal disorders where nausea is debilitating.
Short-term management of severe behavioral manifestations in psychosis requiring rapid symptom control.
Pharmacologic control of delirium-associated nausea and vomiting in hospitalized patients.
Palliative control of nausea and vomiting in terminally ill patients where oral administration is not feasible.
Treatment of nausea and vomiting related to vestibular disorders as part of an integrated approach.

Side Or Adverse Effects

Drowsiness and sedation leading to impaired mental and physical abilities, especially early in therapy.
Extrapyramidal symptoms including dystonia, pseudoparkinsonism, akathisia, and tardive dyskinesia.
Hypotension, particularly orthostatic, due to alpha-adrenergic blockade.
Neuroleptic Malignant Syndrome (NMS), a rare but life-threatening condition with hyperpyrexia and muscle rigidity.
Cholestatic jaundice and hepatic dysfunction manifested by abnormal liver function tests.
Leukopenia, neutropenia, and agranulocytosis requiring monitoring of white blood cell counts.
Contact dermatitis upon dermal exposure to the injectable preparation.
Blurred vision and other anticholinergic effects such as dry mouth and urinary retention.
Amenorrhea, gynecomastia, galactorrhea, and other endocrine disruptions due to prolactin elevation.
Photosensitivity reactions causing skin erythema and rash.
Cardiac arrhythmias and EKG changes including Q and T wave alterations.
Gastrointestinal side effects including nausea (paradoxical), constipation, and ileus.
Motor restlessness and agitation, which may mimic worsening psychiatric symptoms.
Weight gain and increased appetite during chronic use.
Potential for seizures in predisposed individuals due to lowered seizure threshold.

Precautions

Monitor for extrapyramidal symptoms, especially in children, elderly, and dehydrated patients.
Use cautiously in patients with a history of bone marrow depression or previous hypersensitivity to phenothiazines.
Avoid use in pediatric patients under 2 years of age or under 20 lbs due to increased risk of adverse reactions.
Monitor complete blood counts periodically due to risk of leukopenia and agranulocytosis.
May mask signs of overdosage of other drugs or obscure diagnosis of conditions producing nausea.
Use cautiously in patients with cardiovascular impairment due to risk of hypotension.
Avoid abrupt discontinuation in long-term users to prevent withdrawal symptoms such as nausea, vomiting, and tremulousness.
Caution when used concomitantly with CNS depressants due to potentiation of sedation.
Exercise care in patients with glaucoma due to anticholinergic properties causing increased intraocular pressure.
Use cautiously in patients exposed to extreme heat due to impairment of thermoregulation.
Cautiously use in pregnant women, only if potential benefit justifies the potential risk to fetus.
Monitor for neuroleptic malignant syndrome and discontinue if suspected.
Use caution in patients receiving lithium due to risk of encephalopathic syndrome.
Assess fall risk particularly in elderly patients due to sedation and orthostatic hypotension.
Adjust dosing carefully in elderly patients due to increased sensitivity and altered pharmacodynamics.

Warnings

Increased mortality risk in elderly patients with dementia-related psychosis; not approved for this use.
Potentially irreversible tardive dyskinesia may develop with chronic use; minimize duration and dosage.
Neuroleptic Malignant Syndrome is a potentially fatal complication requiring immediate drug discontinuation.
Use contraindicated in comatose states or in presence of large amounts of CNS depressants (alcohol, barbiturates, narcotics).
Hypotension risk, especially with intravenous administration; monitor blood pressure closely.
Avoid subcutaneous injections due to severe local irritation.
Not to be used in pediatric surgery or conditions lacking established pediatric dosage.
May cause sedation leading to impairment in activities requiring alertness such as driving or operating machinery.
Possible cardiac arrest or sudden death reported; monitor cardiac status closely, especially in patients with cardiovascular disease.
Potential for severe skin reactions including photosensitivity and allergic reactions.
Phenothiazines may intensify CNS depressants’ effects; combined use requires caution.
Pregnancy use associated with neonatal extrapyramidal and withdrawal symptoms; avoid unless benefits outweigh risks.
Warning against abrupt cessation in chronic users due to withdrawal symptoms.
Use with caution in patients with seizure disorders due to lowered seizure threshold.
Elevated prolactin levels may have unknown long-term effects; caution in patients with breast cancer.

Contraindication

Known hypersensitivity to phenothiazines or prochlorperazine edisylate.
Comatose states or severe central nervous system depression.
Use in pediatric patients under 2 years of age or weighing less than 20 pounds.
Pediatric surgery due to increased risk of extrapyramidal and other severe reactions.
Concurrent use with large amounts of CNS depressants including alcohol, barbiturates, and narcotics.
Known history of bone marrow depression or blood dyscrasias caused by phenothiazines.
Patients with untreated narrow-angle glaucoma.
Patients with severe cardiovascular disease predisposing to hypotension and arrhythmias.
Those with known history of neuroleptic malignant syndrome related to antipsychotic use.
Known hypersensitivity or allergy to any component of the injectable formulation including benzyl alcohol.

Drug Interactions

Concomitant use with CNS depressants (alcohol, barbiturates, narcotics) may potentiate sedation and respiratory depression.
Phenothiazines may diminish the anticoagulant effects of oral anticoagulants, requiring monitoring of coagulation parameters.
Phenothiazines can potentiate hypotensive effects when used with antihypertensive agents, especially guanethidine-like drugs.
Propranolol coadministration may increase plasma concentrations of both drugs, necessitating dose adjustments.
Thiazide diuretics may exacerbate orthostatic hypotension induced by prochlorperazine.
Phenothiazines may interfere with phenytoin metabolism, increasing risk of phenytoin toxicity.
Use with metrizamide or other contrast agents used in myelography should be avoided due to increased risk of seizures.
Beta-blockers and certain calcium channel blockers may have altered efficacy or increased side effects when combined.
Drugs lowering seizure threshold should be used cautiously as prochlorperazine may add to this effect.
Amphetamines or other stimulants may counteract prochlorperazine effects but carry risk of arrhythmias.
Other anticholinergic drugs may potentiate anticholinergic adverse effects of prochlorperazine.
Phenothiazines may cause false-positive results in phenylketonuria testing.
Concurrent use with other QT-prolonging medications may increase risk of cardiac arrhythmias.
Drugs metabolized by cytochrome P450 enzymes may have altered levels due to prochlorperazine metabolism involvement.
Coadministration with lithium may increase risk of encephalopathic syndrome.

Preparations Of The Drug

Prochlorperazine Edisylate Injection USP: 5 mg/mL sterile solution, supplied in 2 mL vials (10 mg per vial).
Inactive ingredients include monobasic sodium phosphate monohydrate, sodium tartrate dihydrate, saccharin sodium, benzyl alcohol as preservative, and water for injection.
Store protected from light at controlled room temperature (20º-25ºC; 68º-77ºF), with excursions permitted between 15º-30ºC (59º-86ºF).
Discard solution if markedly discolored, indicating potential degradation.
Packaged as 25 vials per carton for hospital or clinical use.
For deep intramuscular or slow intravenous administration only; subcutaneous injection not recommended due to irritation.
Should not be mixed with other agents in the same syringe to avoid incompatibilities.
Contains benzyl alcohol as a preservative; avoid use in neonates and low-birth-weight infants due to risk of toxicity.
Sterile, pyrogen-free solution formulated for parenteral administration with pH of approximately 4.2-6.2.
Manufactured by Hikma Pharmaceuticals USA Inc., following standard pharmaceutical quality controls.
Intended for prescription use only with appropriate clinical monitoring.
Patient education includes caution regarding possible sedation and risks of orthostatic hypotension.
Special handling instructions include protecting from light and inspecting for particulates or discoloration before administration.
Not available in oral or other solid dosage forms in this presentation; oral forms of prochlorperazine exist separately as tablets and suppositories.
Supply includes National Drug Code (NDC) 0641-6135 for inventory and billing purposes.