1. Clinical Overview
Propofol is a short-acting, intravenous general anesthetic agent. It is a highly lipophilic compound chemically described as 2,6-diisopropylphenol. In the Indian context, it is a cornerstone of modern anesthesia practice, widely used for induction and maintenance of general anesthesia, procedural sedation, and in intensive care units (ICUs) for sedation of mechanically ventilated adults. Its rapid onset and offset of action, along with a favorable recovery profile with minimal post-operative nausea and vomiting (PONV), make it a preferred agent. It is formulated as a white, oil-in-water emulsion (1% = 10 mg/mL) containing soybean oil, glycerol, egg lecithin, and sodium hydroxide. It is not an analgesic.
| Onset | Duration | Bioavailability |
|---|---|---|
| 9 to 51 seconds (for induction of anesthesia, dose-dependent) | 3 to 10 minutes (single bolus dose) | 100% (Intravenous administration) |
2. Mechanism of Action
Propofol's primary mechanism involves potentiation of the inhibitory neurotransmission mediated by gamma-aminobutyric acid (GABA) at the GABA-A receptor. It binds to a specific site on the beta subunit of the receptor, distinct from the benzodiazepine site, enhancing the affinity of GABA for its receptor. This increases chloride ion conductance through the receptor-channel complex, leading to neuronal hyperpolarization and inhibition of synaptic transmission.
3. Indications & Uses
- Induction and maintenance of general anesthesia in adults and pediatric patients >3 years
- Monitored Anesthesia Care (MAC) sedation for diagnostic and surgical procedures
- Sedation of intubated, mechanically ventilated adult patients in Intensive Care Units (ICU)
4. Dosage & Administration
Adult Dosage: INDUCTION: 1.5 to 2.5 mg/kg IV (approx. 100-200 mg for avg adult) injected over 10-20 seconds. MAINTENANCE: 100-200 mcg/kg/min (6-12 mg/kg/hr) IV infusion, titrated to effect. ICU SEDATION: 5-50 mcg/kg/min (0.3-3 mg/kg/hr) IV infusion, titrated to sedation score (e.g., RASS). MAC: Initial 0.5 mg/kg IV bolus, then 10-50 mcg/kg/min infusion or incremental 10-20 mg boluses.
Administration: For IV use ONLY. Must be administered by a person trained in general anesthesia. Check for emulsion integrity (white, homogeneous). Use strict aseptic technique. Draw up immediately before administration. Do not mix with other drugs or infusion fluids in the same syringe/line. Can be infused via a dedicated line or via a Y-site close to the venous access using compatible fluids (5% Dextrose, 0.9% Sodium Chloride). Flush line before and after administration. Monitor ECG, BP, SpO2, and respiratory function continuously. Resuscitation equipment must be available.
5. Side Effects
Common side effects may include:
- Pain on injection (can be mitigated with lidocaine pre-mixing or use of larger veins)
- Transient apnea (30-60 sec)
- Hypotension
- Bradycardia
- Involuntary skeletal muscle movements (myoclonus)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Benzodiazepines (e.g., Midazolam) | Enhanced sedative, hypnotic, and respiratory depressant effects. Dose reduction required. | Major |
| Opioids (e.g., Fentanyl, Morphine) | Potentiation of respiratory and cardiovascular depression. Hypotension and apnea risk increased. | Major |
| Inhaled Anesthetics (e.g., Sevoflurane) | Additive cardiovascular depressant effects. Reduced propofol requirements. | Moderate |
| Antihypertensives, Vasodilators | Increased risk of severe hypotension. | Moderate |
| CNS Depressants (Alcohol, Barbiturates) | Additive CNS depression. | Major |
| Theophylline | Antagonizes the sedative effect of propofol; may increase seizure risk. | Moderate |
7. Patient Counselling
- DO inform your doctor about all allergies, especially to eggs, soy, peanuts.
- DO inform about all medications, including herbs and supplements.
- DO arrange for someone to drive you home after the procedure.
- DO NOT eat or drink (fast) as instructed before the procedure (typically 6-8 hours for solids, 2 hours for clear liquids).
- DO NOT make important decisions or sign legal documents for 24 hours post-procedure.
8. Toxicology & Storage
Overdose: Profound cardiovascular depression (severe hypotension, bradycardia, asystole), respiratory depression/apnea, loss of protective reflexes, coma.
Storage: Store below 25°C. Do not freeze. Protect from light. The emulsion is for single use only. Once the vial/ampoule is opened, it must be used immediately. Any unused portion must be discarded. Do not use if the emulsion is discolored, separated, or contains particulate matter.