1. Clinical Overview
Propofol is a short-acting, intravenous general anesthetic agent belonging to the alkylphenol class. It is a milky white emulsion used for the induction and maintenance of general anesthesia, procedural sedation, and sedation in intensive care units (ICU). It is characterized by a rapid onset and short duration of action, with a favorable recovery profile and minimal post-operative nausea and vomiting. In India, it is a critical drug in modern anesthesia practice.
| Onset | Duration | Bioavailability |
|---|---|---|
| 9 to 51 seconds (one arm-brain circulation time) | 3 to 10 minutes (dose-dependent) | 100% (Intravenous administration) |
2. Mechanism of Action
Propofol potentiates GABAergic neurotransmission by binding to beta subunits of the GABA-A receptor, increasing the receptor's affinity for GABA. This enhances chloride ion influx, leading to neuronal hyperpolarization and inhibition of synaptic transmission. It also inhibits the NMDA receptor and modulates calcium ion influx through slow calcium channels.
3. Indications & Uses
- Induction and maintenance of general anesthesia
- Sedation for mechanically ventilated adults in Intensive Care Units (ICU)
- Procedural sedation (e.g., endoscopy, cardioversion, minor surgical procedures)
4. Dosage & Administration
Adult Dosage: Induction: 1.5 to 2.5 mg/kg IV bolus. Maintenance: 100 to 200 mcg/kg/min IV infusion (6-12 mg/kg/hr). ICU Sedation: 0.3 to 4.0 mg/kg/hr (5-67 mcg/kg/min) IV infusion. Procedural Sedation: 0.5 to 1 mg/kg bolus followed by 25-75 mcg/kg/min infusion.
Administration: For IV use only. Use strict aseptic technique. Inspect for particulate matter/discoloration. Do not use if emulsion is separated. Can be administered as a slow IV bolus (over 20-30 seconds for induction) or as a controlled continuous infusion using a syringe or volumetric pump. Flush IV line to prevent pain on injection (can be pre-treated with lidocaine). NEVER administer via the same IV line concurrently with blood or plasma.
5. Side Effects
Common side effects may include:
- Pain at injection site (up to 70%)
- Transient apnea (30-60%)
- Hypotension (10-30%)
- Bradycardia (5%)
- Involuntary muscle movements (myoclonus)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Benzodiazepines (Midazolam, Diazepam) | Potentiated sedative, hypnotic, and respiratory depressant effects. Dose reduction required. | Major |
| Opioids (Fentanyl, Morphine) | Synergistic increase in sedation, analgesia, and respiratory depression. Profound hypotension and bradycardia possible. | Major |
| Inhaled Anesthetics (Isoflurane, Sevoflurane) | Additive CNS and cardiovascular depressant effects. | Moderate |
| Clonidine | Enhanced hypotensive and bradycardic effects. | Moderate |
| Theophylline | Antagonizes CNS depressant effects of propofol; may require higher doses. | Moderate |
7. Patient Counselling
- Do inform your doctor about all allergies, especially to eggs, soy, and other drugs.
- Do inform about all medications, including herbs and supplements.
- Do follow pre-operative fasting instructions (NPO).
- Do not drive or operate heavy machinery for at least 24 hours post-procedure.
- Do not consume alcohol for 24 hours.
8. Toxicology & Storage
Overdose: Profound cardiovascular depression (severe hypotension, bradycardia, asystole), respiratory arrest, deep coma, metabolic acidosis.
Storage: Store below 25°C. Do not freeze. Protect from light. Keep in original outer carton. Once the vial/ampoule is opened, use immediately. Discard any unused portion. The emulsion is for single use in one patient only. Do not use if there is evidence of separation of the emulsion.