Lecture 8 Topical Products Formulation

Question 1

What are ideal physical properties of topical formulations?

Answer 1

• smooth in texture
• elegance in appearance
• non dehydrating
• easy to apply

Question 2

What are ideal physiological properties of topical formulations?

Answer 2

• non irritating
• do not alter membrane function
• low sensitisation effect
• prolonged release

Question 3

What properties should be considered before preformulation?

Answer 3

• lipophilicity
• hydrogen bonding
• molecular weight/melting point
• permeability coefficient (Kp)

Question 4

What are the 2 typical preformulation parameters?

Answer 4

LogP (partition coefficent) = reflects how well a drug parititions between lipid and water

pKa (dissociation constant) = measure of strength of an acid/base and allows the determination of charge on molecule given pH

Question 5

What are the ideal properties of drug?

3 points

Answer 5

1. Moderately lipophilic, log P= 1-4
2. Relatively low mol. weight, < 500 daltons
3. Effective at low doses < 10mg a day

Question 6

What are the main roles of excipients?

Answer 6

• Improve solubility to allow incorporation of drug
• Improving general aesthetic of product to increase patient compliance
• Improve drug formulation stability
• Prevention of microbial growth and contamination

Question 7

What are commonly used excipients?

Answer 7

• Solvents and co-solvents
• Humectants
• Emollients
• Permeation Enhancers

Question 8

What are some physical enhancers?

Answer 8

Ultraound
Iontophoresis
Electroprotion
Sonophoresis
Microneedles

Question 9

What are ideal characteristics of chemical penetration enhancers?

Answer 9

• Reversibly reduce the barrier resistance of SC without damaging cells
• Non toxic, non irritating and non-allergic
• Work rapidly
• No pharmacological activity within the body

Question 10

What are some common examples of commonly used chemical penetration enhancers?

Answer 10

Water
Sulfide
Azons
Surfactants