Compazine (Prochlorperazine) – Patient Information for Australian Use
Basic Product Information
| International Non-proprietary Name (INN) | Prochlorperazine |
|---|---|
| Australia Brand Names | Compazine, Stemetil |
| ATC Code | N05AB04 |
| Available Forms & Strengths | Tablets (5 mg, 10 mg), Buccal tablets (3 mg), Suppositories (5 mg, 25 mg), Injectable (12.5 mg/mL ampoules) |
| Manufacturers | Sanofi-Aventis, Baxter Healthcare, Mylan, various |
| Prescription Status | S4 – Prescription Only Medicine (Schedule 4) |
Mechanism of Action
Simplified explanation: Prochlorperazine (Compazine) works in the brain to help reduce nausea, vomiting, and symptoms of vertigo (dizziness) by blocking the action of dopamine—a chemical that can trigger these symptoms.
For healthcare professionals: Prochlorperazine is a phenothiazine derivative with strong antidopaminergic activity. By antagonising D2 dopamine receptors — primarily in the chemoreceptor trigger zone (CTZ) of the brain — it suppresses vomiting reflexes and also exerts moderate anticholinergic and antihistaminic effects. This mechanism underpins its antipsychotic, anti-emetic, and anxiolytic properties.
Pharmacokinetics
- Absorption: Well absorbed orally; peak blood levels reached in 1–2 hours (oral), 20–60 minutes (buccal, intramuscular).
- Distribution: Widely distributed; crosses blood-brain barrier; highly protein-bound.
- Metabolism: Extensively metabolised in the liver, primarily by CYP2D6 enzymes.
- Elimination: Metabolites excreted mainly in urine and bile; minor amounts unchanged in urine.
- Duration of Action: Symptom relief typically lasts 4–8 hours.
Use in Everyday Life and Best Practices
Prochlorperazine is mainly used in Australia for the short-term treatment of severe nausea and vomiting, including that associated with migraine or vertigo, as well as for the management of acute psychotic episodes. It is not intended for long-term management of mental illness except under specialist supervision.
Typical adult doses: 5–10 mg two to three times daily for nausea. Migraine-associated nausea: a single 5 mg dose (may repeat every 8 hours as required, max 30 mg in 24 hours). For vertigo: 5 mg up to three times daily.
How to take: Tablets should be swallowed whole with a full glass of water. Buccal tablets are placed between the gums and cheek to dissolve. Suppositories are inserted into the rectum. Always follow your doctor’s or pharmacist’s instructions.
- Do not exceed prescribed dose or duration.
- Contact a healthcare professional if symptoms persist or worsen.
- Store in a cool, dry place—out of reach of children.
Dosing: Morning vs Evening
- Morning dosing: May be helpful for morning symptoms or to avoid interference with nighttime sleep. However, some people experience drowsiness.
- Evening dosing: May reduce daytime sedation but can sometimes interfere with restful sleep depending on individual sensitivity. Best discussed with your doctor if you feel excessively sleepy during the day.
- Tip: Aim to take doses at the same time each day for the best effect and to maintain steady levels in your system.
Taking with Food or on an Empty Stomach
- Can be taken with or without food.
- Taking with food may help reduce the risk of stomach irritation—particularly with typical English and Australian diets that include regular meals with dairy, grain, and protein.
- Avoid alcohol and excessive caffeine as these may interact adversely with the medicine or worsen side effects like drowsiness and confusion.
Interaction Warnings
| Interaction Type | Examples | Comment |
|---|---|---|
| Alcohol | Beer, wine, spirits | Increases drowsiness and risk of side effects |
| Other CNS depressants | Sleeping pills, strong pain relievers (opioids), some antihistamines | May increase sedation, confusion, risk of falls |
| Anticholinergic drugs | Certain bladder medicines, antidepressants | May worsen dry mouth, constipation, confusion |
| Levodopa or dopamine agonists | Parkinson’s medications | May reduce their effectiveness |
| Antihypertensives | Blood pressure tablets | May increase risk of low blood pressure (dizziness, fainting) |
| CYP2D6 inhibitors | Fluoxetine, paroxetine | May increase prochlorperazine levels |
Indications
| Official/Primary | Off-label/Additional |
|---|---|
|
|
Dosing According to Clinical Indication
| Indication | Adults | Children (5–17 yrs) | Elderly |
|---|---|---|---|
| Nausea & Vomiting | 5–10 mg 2–3 times daily | 1–2.5 mg 2–3 times daily (max 7.5 mg/d); under specialist oversight | Start low (e.g. 2.5–5 mg once/twice daily); monitor for sedation, falls |
| Migraine-associated nausea | 5 mg at migraine onset; repeat every 8 hours PRN, max 30 mg/day | As per above; specialist advice required | Lower doses; avoid if high falls risk |
| Vertigo | 5 mg 2–3 times daily | Use only on specialist advice | Start with lowest effective dose |
| Acute psychosis | 12.5 mg IM injection; repeat after 6–8 hours if required | Rare; specialist only | Lower initial doses, monitor closely |
Please note: Doses for children under 5 years are not recommended except under strict specialist supervision. Always consult your doctor for individualised dosing.
Safety Profile and Side Effects
| Side Effect | Frequency | Warning/Advice |
|---|---|---|
| Drowsiness, fatigue | Common | Avoid driving or using heavy machinery if affected |
| Dry mouth, constipation | Common | Maintain hydration, high-fibre diet |
| Blurred vision, difficulty urinating | Occasional | Report to doctor if troublesome |
| Low blood pressure (hypotension) | Occasional | Get up slowly from sitting/lying positions |
| Extrapyramidal effects (muscle stiffness, tremor, restlessness) | Rare | Seek medical attention if sudden |
| Allergic reaction, rash, swelling | Very rare | Immediate medical help required |
| Jaundice/liver problems | Very rare | Stop and seek urgent advice if yellow skin/eyes |
| Neuroleptic malignant syndrome | Extremely rare | Stop and seek emergency help (high fever, muscle stiffness, confusion) |
- Long-term use is not recommended due to potential for movement disorders (tardive dyskinesia), especially in the elderly.
- Higher risk of side effects in very young, elderly, or people with pre-existing medical conditions.
Guidelines for Proper Use (Australian Pharmacy Advice)
- Take your medicine as prescribed, and finish the full course even if you feel better, unless your doctor advises otherwise.
- Do not double up the dose if you miss one; simply take the next scheduled dose on time.
- Check with your pharmacist before taking any new medicines, supplements, or herbal remedies.
- Let your doctor know if you have liver or kidney problems, glaucoma, prostate issues, epilepsy, or Parkinson’s disease.
- Do not drive or cycle if you feel drowsy, dizzy, or have blurred vision.
- If you become pregnant or need to breastfeed, discuss the risks and benefits with your healthcare provider.
Alternative Treatment Options
- Metoclopramide: Also available through the PBS (Pharmaceutical Benefits Scheme). Similar antiemetic effect, but risk of movement disorders with prolonged use.
- Ondansetron: Effective, fewer movement side effects; more expensive and reserved mostly for chemotherapy- or surgery-induced nausea.
- Domperidone: Occasionally used for certain types of nausea, with fewer central nervous effects; available with restrictions.
- Pantoprazole, Omeprazole (proton pump inhibitors): Not antiemetics, but may help where nausea is linked to acid reflux or gastropathy.
Choice of antiemetic depends on underlying cause, other medical conditions, and possible side effects. Discuss options with your prescriber or pharmacist.
Legal, Registration, and Reimbursement Status in Australia
- Legal classification: Compazine (Prochlorperazine) is a Schedule 4 (S4) substance in Australia—available only on a doctor’s prescription.
- Regulatory approval: Registered with the Therapeutic Goods Administration (TGA).
- Reimbursement: Subsidised under the Pharmaceutical Benefits Scheme (PBS) for approved indications (nausea, vomiting, migraine, vestibular disorders).
- Pack sizes: Commonly dispensed in 25 or 100 tablet bottles; suppositories in trays of 5–10 units.
Latest Research and Clinical Guidance (2022–2025)
Recent Australian and international guidelines (NPS MedicineWise 2023; NICE UK 2024) continue to recommend prochlorperazine as an effective, short-term treatment for nausea, vomiting, and vertigo, particularly where first-line agents are unsuitable. Caution is urged in children, elderly, pregnant women, and those at risk of movement disorders. Ongoing research has compared safety profiles with newer agents such as ondansetron and found prochlorperazine remains a cost-effective, rapidly acting option when used appropriately. (For further information, consult your GP or refer to the TGA and Australian Medicines Handbook).
Availability and Delivery
| Pack Size | Typical PBS Price (AUD)* | Availability | Delivery to Sydney, Melbourne, Brisbane | Delivery to Perth, Adelaide, Darwin |
|---|---|---|---|---|
| 25 Tablets (5mg, 10mg) | $6.70 concession, $30.00 general | Widely available | 1–2 business days | 2–4 business days |
| Suppositories (5mg, 25mg – 5 units) | $7.10 concession, $32.00 general | Selective pharmacies | 1–2 business days | 2–4 business days |
| Injectable (5 ampoules/box 12.5mg/mL) | Hospital supply only | Hospital use | N/A | N/A |
*Prices indicative as of mid-2024; check with your pharmacist for current rates and private prescription prices. Standard home delivery options available Australia-wide; cold chain not required.
FAQ – Common Patient Questions
- Can I drive or work after taking Compazine?
Many people feel drowsy or less alert when taking Compazine. It is not recommended to drive, operate machinery, or undertake hazardous tasks until you know how the medicine affects you. - Can I drink alcohol while on Compazine?
Alcohol may increase sedative effects and raise the risk of dangerous side effects such as confusion or falls. Avoid alcohol while taking this medicine. - What should I do if I miss a dose?
Take your next scheduled dose as normal; do not double up. Consistent dosing at the same times each day helps maintain effectiveness. - Is Compazine safe in pregnancy or breastfeeding?
It is not generally recommended during pregnancy or breastfeeding unless your doctor considers it essential. Always discuss with your healthcare provider before use. - How soon will I feel better?
Compazine usually provides relief from nausea or vertigo within 1–2 hours (oral) or even faster (injectable, buccal forms). If your symptoms persist or worsen, seek medical advice.
Disclaimer: This information is for general guidance. It does not replace advice from your doctor or pharmacist. Always follow professional recommendations tailored to your personal health situation. For more details, please speak directly with a registered Australian healthcare professional.
