Pharmacology

Question 1

What are the 3 ways in which IV induction agents can be classified?

Answer 1

Barbiturates (Thiopentone, methohexital)
Non-barbiturates (Propofol, Etomidate, ketamine)
Hypnotics (benzodiazepines)

Question 2

What is an emulsion?

Answer 2

Mixture of two or more liquids which are not soluble with each other, so the first liquid must be dispersed as smaller droplets throughout the second liquid.

Question 3

What is the dispersed phase and continuous phase of liquids in an emulsion?

Answer 3

Dispersed phase = first liquid dispersed as tiny droplets.
Continuous phase = second liquid in which the first liquid is dispersed or spread throughout.

Question 4

What is an emulsifying agent?

Answer 4

It is an additional substance that acts as an intermediate between the dispersed and continuous phases to prolong the stability of the emulsion.

Question 5

In Propofol, what is the:
a. Dispersed phase
b. Continuous phase
c. Emulsifying agent

Answer 5

a. 2,6-diisopropylphenol (propofol)
b. Soybean oil
c. Egg phosphatide from egg lecithin

Question 6

What are some problems with soybean emulsions? (5)

Answer 6

Emulsion instability
Pain on injection (pH 10,4)
Microbial contamination
Emulsion emboli
Hyperlipidaemia

Fat white chicks mnemonic: Unstable, pain in the ass contamination in your life. Are fat (hyperlipidaemia) and prone to emboli.

Question 7

Explain following emulsion droplet terminology:
a. Flocculation
b. Creaming
c. Coalescence
d. Cracking

Answer 7

Flocculation: small droplets adhere (birds flock together)
Creaming: Larger droplets rise to the surface (like cream in milk/coffee)
Coalescence: Larger droplets rupture
Cracking: More collisions and droplets broken