Self Assessment Questions for ointments

Question 1

Discuss how well hydrocarbon (oleaginous) bases meet the criteria for an ideal ointment base

Answer 1

Very well as it has the following properties and can combine with other constituents to form absorption or emulsion bases

• Emollient
• Occlusive - limiting the evaporation of moisture from the skin (Pastes less so, due to presence of powders)
• Non-water washable (not readily removed from skin)
• Hydrophobic - have a low capacity to absorb water – presence of powders in pastes increases absorptivity

Question 2

Compare and contrast Ointment and Paste formulations

Answer 2

Pastes are ointments which contain a much higher proportion (20-50%) of fine powders

• Higher powder content –> allows evaporation + powders can absorb exudate when with hydrocarbon base
• Stiff consistency – much stiffer than ointments. Viscosity (dilatant flow) makes application difficult
• Gels may be used as bases for pastes

> Both are used on skin and for mostly local effect

> Same types of bases are used for both except for absorption bases (not used in pastes)

Question 3

Describe the factors that may contribute to poor patient compliance with treatment using an ointment

Answer 3

• Greasy
• Difficult to remove
• Staining of clothes
• High viscocity –> ointments are difficult to apply

Question 4

Discuss the properties and typical constituents of Water Soluble ointment bases

Answer 4

Properties

• Anyhdrous (usually)
• Non-greasy
• Non-occlusive
• Lipid free
• Water soluble and washable

Constituents

• Macrogols = Polethylene Glycols (PEG) –> identified by moelcular weight
• 200-600 are viscous, colourless, hygroscopic liquids
• > 1000 and above are wax like solids
• Consistency of base varied by adjusting the balance of liquid and solid macrogols

Question 5

Compare and contrast Absorption and Water Miscible ointment bases

Answer 5

Differences

• Absorption is hydrophobic, water miscible is hydrophilic
• Absorption is greasy, water miscible is non-greasy
• Absorption is occlusive, water miscible is non-occlusive
• Absorption is non-washable, water miscible is washable

Question 6

Discuss five therapeutic agents that may be formulated into ointments and indicate the area of the skin at which they are targeted

Answer 6

1. Emollients –> smooth SC, reduce moisture loss eg fixed oils
2. Humectants –> attract and retain transepidermal water at SC eg glycerol
3. Anti-proliferatives - Reduce the thickness of the epithelium eg Coal Tar
4. Keratolytics –> reduce thickness of SC eg salicylic acid
5. Anti-pruritics – relieve itching (epidermis) eg menthol

Question 7

Describe suitable agents that could be added to a hydrocarbon ointment base to improve its water absorbing capabilities

Answer 7

Addition of hydrophilic materials