Duration of action

Propofol only has a relatively short duration of action. This is mainly due to the short plasma half-life, which is associated with a rapid reduction in blood concentration. After application, the effect sets in within 10 to 20 seconds and decreases after about eight to nine minutes if no further application is made. To maintain an anesthesia or a twilight state, multiple applications or a continuous infusion (continuous infusion) must be made.

Dosage

A dose of 20 to 40 mg every ten seconds is usually used to induce anaesthesia. This continues until the patient clinically demonstrates a state of unconsciousness. Up to the age of 55, the usual dose for adults is 1.5 – 2.5 mg propofol/kg body weight.

Older people have a lower need for Propofol for anaesthetic induction. The same applies to patients with an increased risk of complications during surgery. Anaesthesia is maintained with a dose of 4 – 12 mg propofol/kg body weight per hour.

For pure sedation, i.e. to achieve a twilight state, a dosage of 0.3 to 4 mg propofol/kg body weight/hour is sufficient. The dosage in children should be considered separately and is generally higher (3-5 mg/kg body weight). Despite the good tolerability and controllability, some significant side effects exist.

In fact, Propofol has a narrow therapeutic range, which means that there is not much margin between the desired effect and the undesired side effect. It is therefore not far from the optimal dosage to the range of over- or under-dosage. As a side effect, Propofol has a damping effect on breathing and heartbeat.

Furthermore, a drop in blood pressure is caused by reduced vascular resistance. Older patients and those with previous heart diseases are particularly affected.Rarely observed undesirable effects are vivid dreams, sometimes experienced as unpleasant, pain and swelling at the site of the injection, twitching of individual muscles, coughing, cramps and severe allergic reactions to, among other things, the soybean oil contained in the product, which is a solvent that gives propofol its white milky color. The occurrence of pulmonary edema is described even more rarely when propofol is administered.

If the anaesthetic is injected incorrectly into the tissue instead of into the vein, serious tissue reactions may occur. The so-called propofol infusion syndrome (PRIS) is a very rare complication and describes a life-threatening complex of symptoms after administration of propofol. It is frequently associated with very high dosages and infusions over a long period of time.

The exact cause is still unknown. Disturbances of normal heart function and rhythm as well as metabolic acidosis (hyperacidity due to defective metabolic processes) occur in most cases. Rhabdomyolysis (dissolution of the skeletal muscles) and acute kidney failure are also among the common symptoms of the infusion syndrome. In addition to circulation-supporting measures, the immediate discontinuation of propofol administration is the most important therapeutic step.