Propofol: characteristics and side effects of this drug

Sedative and anesthetic medications are one of the basic tools in many operating rooms and intensive care spaces.

Sedation and induction of anesthesia are necessary in many medical acts and surgical interventions, since they block the tactile and painful sensitivity of the patients, and facilitate the work of the professionals. In this sense, one of the most widely used drugs is propofol, a powerful, fast-acting sedative used as an anesthetic.

In this article we explain what propofol is, what are its clinical uses, its mechanism of action, as well as the most common side effects caused by this drug.

• Related article: "Types of psychotropic drugs: uses and side effects"

Propofol: characteristics and clinical uses

Propofol is a drug from the group of fast-acting sedative-hypnotics that is usually given intravenously. It was discovered in 1977 and approved for marketing in 1989, and is currently considered a safe and effective drug. In some countries it is known as "milk of amnesia", due to the rapid induction of sleep and anesthesia it produces.

This medicine is used to initiate and maintain sedation in monitored anesthetic care, in combined sedation and local anesthesia, in induction of general anesthesia and in intensive care when intubated or ventilated patients need to be sedated mechanics. Propofol works quickly; Its peak effect takes about two minutes to produce and generally lasts five to ten minutes.

With everything, there have been reports of the abuse of propofol for recreational and other inappropriate purposes, which have resulted in deaths and other injuries. Cases of self-administration of propofol by health professionals have also been reported, with similar episodes. Propofol was also used in executions of prisoners sentenced to death, although its use for this purpose was banned in 2013.

Effects and mechanism of action

The mechanism of action of propofol, as occurs with the vast majority of anesthetic drugs, is unknown; however, it has been suggested that this drug produces its sedative and anesthetic effects by modulating positive inhibitory function of the neurotransmitter GABA, through GABAa receptors activated by ligand.

The pharmacodynamic properties of propofol depend on the concentrations of the drug in the blood. In patients who maintain spontaneous ventilation, the main cardiovascular effect of propofol is high blood pressure, with little or no change in heart rate, and without an appreciable decrease in cardiac output; however, if ventilation is assisted, there is an increase in the incidence and degree of cardiac output depression.

Studies have shown that the effects of propofol on induction of anesthesia are generally more pronounced than those of other intravenous induction drugs. Induction of anesthesia with propofol is frequently associated with apnea, both in adults and pediatric patients. During maintenance of anesthesia, propofol causes a decrease in spontaneous minute ventilation, generally associated with an increase in carbon dioxide tension.

During sedation with monitored anesthesia care, hypotension, oxyhemoglobin desaturation, apnea, and airway obstruction may occur. Special caution should be exercised in elderly and debilitated patients, as dosing is discouraged. bolus (single dose administered over a short period of time) for sedation in anesthetic care monitored.

• You may be interested: "GABA (neurotransmitter): what it is and what role does it play in the brain"

Side effects

The clinical use of propofol may lead to a number of risks and possible adverse effects worth considering. One of the most common side effects of propofol is pain at the injection site, especially when it is done in the smaller veins; This pain arises from the activation of the TRPA1 pain receptor, located in the sensory nerves.

When propofol is used in anesthesia or in monitored anesthetic care, the most common side effects include: bradycardia, tachycardia, arrhythmia, hypertension, burning or stinging when moving, pain at the injection site, apnea, skin rash and itching.

In cases where propofol is used for sedation in intensive care units, the most common symptoms are: bradycardia, decreased cardiac output, hypotension, hyperlipidaemia (presence of high levels of lipids in the blood) and respiratory acidosis (increasing concentration of carbon dioxide in the blood plasma and a decrease in the pH in blood).

Although propofol is commonly used in the adult intensive care setting, special emphasis has been placed on side effects affecting pediatric patients, since in the 1990s several deaths of children related to the sedation of this hypnotic and sedative drug were reported. Finally, it should be noted that the respiratory effects of propofol increase if it is administered together with other depressant drugs (including benzodiazepines).

Propofol infusion syndrome

Propofol infusion syndrome is a rare disorder that affects some patients. undergoing long-term treatment with high doses of this anesthetic and sedative drug. This syndrome commonly occurs in children, and critically ill patients who receive catecholamines and glucocorticoids are at increased risk for it.

This disorder can lead to heart failure, rhabdomyolysis (a disease caused by muscle necrosis), metabolic acidosis, and kidney failure, and is often fatal. It can also cause hyperkalemia, increased triglycerides in the blood and enlargement of the liver, consequences that could be due to direct inhibition of the mitochondrial respiratory chain or metabolism of mitochondrial fatty acids deteriorated.

Early recognition of the syndrome and discontinuation of propofol infusion is criticalas it considerably reduces morbidity and mortality. Treatment consists of providing cardiopulmonary support with inotropics (drugs that increase cardiac contraction), vasopressors, and mechanical ventilation. Bradycardia does not usually respond to catecholamine infusion and external pacemaker.

To eliminate propofol and its metabolites, hemodialysis and hemofiltration are recommended. Some patients may require extracorporeal membrane oxygenation assistance. Treatment for rhabdomyolysis includes maintaining intravascular volume and supporting kidney function. And if lactic acidosis occurs, aggressive treatment based on hemodialysis is recommended.

Bibliographic references:

• Kang, T. M. (2002). Propofol infusion syndrome in critically ill patients. Annals of Pharmacotherapy, 36 (9), 1453-1456.
• Mackenzie, N., & Grant, I. S. (1987). Propofol for intravenous sedation. Anesthesia, 42 (1), 3-6.
• Tan, C. H., & Onsiong, M. K. (1998). Pain on injection of propofol. Anesthesia, 53 (5), 468-476.