Compazine

Compazine (prochlorperazine) is a prescription phenothiazine antipsychotic medication primarily indicated for the management of severe nausea and vomiting, as well as the treatment of schizophrenia and anxiety. It functions by blocking dopamine receptors in the brain, which helps to control chemoreceptor trigger zone (CTZ) activity and mitigate emetic signals. This medication is available in multiple formulations, including tablets, suppositories, and injectable solutions, allowing for tailored administration based on clinical need and patient condition. It is typically reserved for cases where first-line antiemetics have proven inadequate, offering a potent therapeutic option under careful medical supervision.

Features

• Active ingredient: Prochlorperazine maleate
• Available formulations: Oral tablets (5 mg, 10 mg), rectal suppositories (25 mg), injectable solution (5 mg/mL)
• Mechanism of action: Dopamine D2 receptor antagonist
• Onset of action: Oral—30–40 minutes; IM—10–20 minutes; IV—rapid; rectal—60 minutes
• Half-life: Approximately 6–8 hours
• Metabolism: Hepatic, via CYP2D6
• Excretion: Primarily renal

Benefits

• Provides rapid and effective control of severe, refractory nausea and vomiting
• Offers flexible administration routes suitable for various clinical scenarios
• Demonstrates additional anti-anxiety and antipsychotic properties in indicated uses
• Can be used adjunctively in migraine-associated nausea
• Helps facilitate oral intake and hydration in acutely ill patients
• Supports continuity of cancer chemotherapy and radiation therapy by managing treatment-induced emesis

Common use

Compazine is commonly prescribed for the management of severe nausea and vomiting not responsive to conventional antiemetics. It is frequently employed in postoperative settings, during cancer chemotherapy, in cases of vertigo-associated emesis, and for severe migraine-related nausea. Off-label, it may be used for acute anxiety or psychotic agitation when other agents are contraindicated or ineffective. Its use is generally short-term due to risks of extrapyramidal symptoms and other adverse effects with prolonged administration.

Dosage and direction

Adults (Nausea/Vomiting):

• Tablets: 5–10 mg 3–4 times daily
• Suppositories: 25 mg twice daily
• IM: 5–10 mg every 3–4 hours (max 40 mg/day)
• IV: 2.5–10 mg (slow infusion; max 40 mg/day)

Elderly/debilitated patients: Lower initial doses (2.5–5 mg) are recommended with careful titration.

Administration with food may reduce gastrointestinal irritation. Avoid abrupt discontinuation after prolonged use.

Precautions

• Use with caution in patients with cardiovascular disease, glaucoma, or seizure disorders
• Monitor for signs of neuroleptic malignant syndrome (NMS) and tardive dyskinesia
• Risk of orthostatic hypotension; advise slow position changes
• May impair mental/physical abilities; caution when operating machinery
• Periodic CBC and liver function tests recommended with prolonged use
• Pregnancy Category C: Use only if potential benefit justifies potential risk
• Excreted in breast milk; not recommended during lactation

Contraindications

• Known hypersensitivity to prochlorperazine or other phenothiazines
• Comatose or severely depressed states
• Bone marrow suppression
• Pediatric patients under 2 years or weighing less than 9 kg
• Concomitant use with large doses of CNS depressants
• Patients with suspected subcortical brain damage

Possible side effect

Common (≥1%):

• Drowsiness, dizziness
• Dry mouth, blurred vision
• Constipation
• Orthostatic hypotension

Less common:

• Extrapyramidal symptoms (dystonia, akathisia, parkinsonism)
• Tardive dyskinesia
• Neuroleptic malignant syndrome
• Galactorrhea, amenorrhea
• Photosensitivity
• Blood dyscrasias
• Jaundice

Drug interaction

• Potentiates effects of CNS depressants (alcohol, opioids, sedatives)
• May antagonize effects of levodopa and dopamine agonists
• CYP2D6 inhibitors (e.g., fluoxetine) may increase concentrations
• Anticholinergic drugs may increase side effects
• May enhance hypotensive effects of antihypertensives
• Caution with QT-prolonging agents

Missed dose

If a dose is missed, take it as soon as remembered unless it is nearly time for the next dose. Do not double doses. If regular dosing schedule is disrupted, contact healthcare provider for guidance.

Overdose

Symptoms may include severe drowsiness, coma, hypotension, extrapyramidal symptoms, agitation, restlessness, convulsions, and cardiac arrhythmias. Treatment is supportive and symptomatic. There is no specific antidote. Gastric lavage may be considered if ingestion was recent. Maintain airway and administer IV fluids for hypotension. Avoid epinephrine for hypotension. Extrapyramidal symptoms may be treated with diphenhydramine or benztropine.

Storage

Store at controlled room temperature (15–30°C or 59–86°F). Protect from light and moisture. Keep suppositories refrigerated. Keep all medications out of reach of children and pets. Do not use after expiration date.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before starting or changing any medication regimen. The prescribing physician should be familiar with the complete prescribing information and monitor patients appropriately.

Reviews

“Compazine was instrumental in managing my chemotherapy-induced nausea when other medications failed. The suppository form was particularly helpful when I couldn’t keep oral medications down.” - Oncology patient, 54

“As an emergency physician, I find Compazine invaluable for acute migraine treatment in the ED. The IV formulation provides rapid relief that often avoids the need for opioid analgesics.” - MD, Emergency Medicine

“While effective for my severe nausea, I experienced significant drowsiness and restlessness that limited my ability to continue long-term use. Required careful dose adjustment.” - Patient with gastroparesis, 32