Propofol: An Overview

Question 1

Describe the three main uses for propofol

Answer 1

1. Induction
2. Maintenance
3. Sedation

Question 2

What is the induction dose of propofol in a young adult?

Answer 2

2mg/kg

Question 3

What is the chemical name for propofol?

Answer 3

2,6 di-isopropyl phenol

Question 4

What is the pH of propofol?

Answer 4

7.4

Question 5

What is the pKa of propofol?

Answer 5

11

Question 6

Propofol is insoluble in water T/F

Answer 6

True. It is formulated as an emulsion, dissolved in soya bean oil emulsified in purified egg phospholipid. The ampoules also contain disodium edetate or metabisulphite to inhibit bacterial growth.

Question 7

Propofol is virtually non-ionized and highly lipid soluble T/F

Answer 7

True

Question 8

The ampoules also contain disodium edetate or metabisulphite to inhibit bacterial growth T/F

Answer 8

True

Question 9

A 1% solution of a substance contains 1 g in __ml?

Answer 9

100ml

Question 10

What volume of a 1% solution would be needed to give 180 mg of propofol to a patient?

Answer 10

18ml

Question 11

Roughly what dose of injected propofol is bound to plasma protein?

Answer 11

98%

Question 12

What is the distribution half life of propofol?

Answer 12

2-8 min

Question 13

What is the elimination half life of propofol?

Answer 13

Up to 6 hours

Question 14

Propofol is very rapidly cleared from the blood and has a clearance rate of 1.5 to 2.2 L/min T/F

Answer 14

True

Question 15

What are the two metabolic pathways involved in metabolism of propofol?

Answer 15

Conjugation to glucuronide and hydroxylation to quinol which is subsequently glucuronidated (liver).

Question 16

Because it is poorly ionized, propofol is highly lipid soluble. True or false?

Answer 16

True

Question 17

What is the definition of pharmacodynamics?

Answer 17

Pharmacodynamics can be considered to be ‘what the drug does to the body’.

Question 18

How does propofol induce hypotension?

Answer 18

An induction dose of propofol reduces the systolic, diastolic and mean blood pressure by about 25 to 40%. This is due to vasodilatation and a reduction in pre and after load. Propofol also has a slightly negative inotropic effect.

Question 19

During induction of anaesthesia, the dose should be titrated against the loss of the eye lash reflex T/F

Answer 19

False. The loss of eye lash reflex is delayed and the dose should be titrated against loss of verbal contact with the patient.

Question 20

Propofol increases the intracranial pressure T/F

Answer 20

False. Propofol reduces cerebral metabolic rate and cerebral blood flow. Intracranial pressure is reduced.

Question 21

Propofol is contraindicated in patients with bronchial asthma T/F

Answer 21

False. Propofol is considered safe to be used in patients with bronchial asthma and chronic airway disease.

Question 22

Propofol has an antiemetic action T/F

Answer 22

True. Propofol has an antiemetic action.

Question 23

In a healthy patient who is having his surgery done as a day-case, propofol would be the agent of choice to induce anaesthesia because of its cardiovascular stability. T/F

Answer 23

False - propofol is the agent of choice for use in day-case surgery, not because of its cardiovascular stability but because of the short duration of action and the superior quality of recovery after its use which allows for early discharge of patients. Its antiemetic property is also useful in day-case anaesthesia. Propofol produces hypotension to a greater extent that other intravenous induction agents.

Question 24

List 4 side effects of propofol

Answer 24

1. Pain on injection
2. Respiratory depression
3. Hypotension
4. Anaphylaxis (rare)

Question 25

Propofol is a barbiturate T/F

Answer 25

False. Propofol is a phenol and not a barbiturate.

Question 26

Propofol is insoluble in water T/F

Answer 26

True. Propofol is insoluble in water and is formulated in soya bean oil and egg phosphatide.

Question 27

Propofol if accidentally injected outside a vein can cause tissue necrosis T/F

Answer 27

False. Unlike thiopental, propofol does not cause tissue necrosis on extravasation.

Question 28

Propofol is mainly excreted unchanged by the kidneys T/F

Answer 28

False. Propofol is metabolised mainly in the liver and also in the lung. Only less than 1% is excreted unchanged by the kidneys.

Question 29

Propofol is highly lipid-soluble T/F

Answer 29

True. Propofol is largely un-ionized and therefore highly lipid-soluble.

Question 30

Propofol decreases arterial blood pressure to a greater degree than thiopental T/F

Answer 30

True. Propofol decreases arterial blood pressure to a greater degree than thiopental.

Question 31

Propofol depresses upper airway reflexes T/F

Answer 31

True. This allows easy passage of laryngeal mask airway after induction with propofol.

Question 32

Propofol causes an increase in cerebral blood flow T/F

Answer 32

False. Propofol reduces cerebral metabolism and reduces cerebral blood flow.

Question 33

Propofol does not affect the ventilatory response to carbon dioxide T/F

Answer 33

False. Propofol depresses the ventilatory response to carbon dioxide.

Question 34

Propofol