Colliodal Dispersed Formulations 1 W2

Question 1

What are dispersed systems

Answer 1

2 phase system in which an insoluble or immiscible dispersed phase Is distributed through a continuous phase

Question 2

What is amoxicillin

Answer 2

Broad spectrum pencilling type antibiotic
For:

o Severe infections of the ear, nose and throat
o Acute exacerbations of chronic bronchitis
o Community acquired pneumonia
o Lyme disease
o Bacterial meningitis

• It can be delivered as tablets or capsules but also as a liquid, orally or intravenously.

Question 3

Solubility and dose of amoxicillin

Answer 3

o Its solubility in water is pH-dependent, ranging from 1.7 mg/mL (4.7 mM) at pH 5.5 to 8.5 mg/mL (23 mM) at pH 7.5.

But…

o The lowest available dosage form is 125mg/5mL, or 25 mg/mL, well above its aqueous solubility.
o it rapidly degrades in aqueous solution

Question 4

How can Amoxicillin be used in a liquid formulation?

Answer 4

Shake powder and mix with water to make a liquid suspension

Question 5

What is calpol

Answer 5

an OTC paediatric formulation of paracetamol

o is a liquid-based formulation
o Paracetamol is very bitter-tasting, and It’s solubility in water is about 14 mg/mL, less than
the dose required (120 mg/5 mL, i.e. 24 mg/mL)…

Question 6

What is gaviscon

Answer 6

is an OTC medicine for acid reflux and indigestion
o Its active ingredients are: sodium alginate and potassium hydrogen carbonate
o The potassium hydrogen carbonate is an antacid,
which neutralises the stomach pH.
o But alginate is the key ingredient

Question 7

Alginates and rafts

Answer 7

o alginate gels at low pH, so it forms a raft on
top of the stomach contents, stopping splashing
back up into the oesophagus.
o To form an effective raft, doses of 250 mg / 10 mL
are delivered.
o Alginate’s solubility is pH-dependent (lowest in acidic pH -> gel-forming ability in stomach)
o Maximum solubility of alginate at pH 6-8 is 10 mg/mL

Question 8

What is a suspension

Answer 8

2 phase dispersed system with a solid dispersed layer and a liquid continuous phase

Question 9

Gas continuous phase and gas dispersed phase

Answer 9

Nothing

Question 10

Liquid continuous phase and gas dispersed phase

Answer 10

Foams

Beer, carbndated drinks, whipped cream

Question 11

Solid continuous phase and gas dispersed phase

Answer 11

Solid foams

Lab, sponges, cakes

Question 12

Gas continuous phase and liquid dispersed phase

Answer 12

Aerosols

Fog, clouds, sprays, sneeze

Question 13

Liquid continuous phase and liquid dispersed phase

Answer 13

Emulsions, creams

Milk, salad dressing, blood, paint

Question 14

Solid continuous phase and liquid dispersed phase

Answer 14

Butter, cheese, jam

Question 15

Gas continuous phase and solid dispersed phase

Answer 15

Smoke, dust, air

Question 16

Liquid continuous phase and solid dispersed phase

Answer 16

Suspensions

Muddy water, medicines

Question 17

Solid continuous phase and solid dispersed phase

Answer 17

Chocolate, paper, coloured glass

Question 18

Particles in pharm suspensions are typically:

Answer 18

0.1 – 10 μm (100 – 10,000 nm)

Question 19

0.1 – 10 μm (100 – 10,000 nm) is an intermediate state between 2 types of dispersed system:

Answer 19

o Colloidal (for particle sizes less than 1 μm, i.e.
nanoscale)
o Coarse (for particles above 1 μm) This distinction is critical for thermodynamic stability

Question 20

If a system is thermodynamically stable ….

Answer 20

It will remain in its present state

Question 21

If a system is thermodynamically unstable ….

Answer 21

It will change in order to reach a stable state

Question 22

Thermodynamic instability flow chart

Answer 22

Dispersion -> sedimentation -> aggregation