10 Questions
What is the primary purpose of emollients in ointments?
To soften the skin
What is the main characteristic of oleaginous bases?
Insoluble in water
What is the classification of ointment bases based on their degree of penetration into the skin?
According to their degree of penetration into the skin
What is natural soft paraffin used for?
Preparation of ophthalmic ointments
What is the purpose of additives in ointments?
To preserve, color, or enhance the ointment
What is the characteristic of hydrocarbon bases such as petrolatum?
A mixture of hard and liquid paraffin
What is a disadvantage of using Plastibase?
It produces a very soft ointment in presence of certain ingredients
What is the purpose of adding stiffening agents to lard?
To improve its consistency
What is the advantage of using absorption bases?
They are easier to spread
What is the effect of hydrogenation on vegetable oils?
It minimizes their rancidity
Study Notes
Ointments
- Semisolid greasy preparations intended for application to the skin
- Used for three purposes: emollients, protection, and as vehicles for drugs to treat skin disorders
Components of Ointments
- Active ingredient: liquid, semisolid, or solid drug
- Additives: preservatives, coloring agents, penetration enhancers, and humectants
- Base "vehicle": incorporates drug and additives
Ointment Bases
Oleaginous Bases
- Absorption bases
- Emulsifying bases (water-miscible base)
- Water-soluble bases
- Examples: hard paraffin, soft paraffin, liquid paraffin, wool fat, wool alcohol, lanolin, cold creams, emollient creams, vanishing creams, shaving creams, cleansing creams, hydrophilic ointment
Characteristics of Ointment Bases
- Spreadability: oleaginous bases (difficult), absorption bases (less difficult), water-soluble bases (easy)
- Washability: oleaginous bases (not washable), absorption bases (not washable), water-soluble bases (washable)
- Absorption of water: oleaginous bases (not absorb), absorption bases (absorb), water-soluble bases (absorb)
- Skin penetration: oleaginous bases (none), absorption bases (moderate), water-soluble bases (high)
Classification of Ointment Bases
- Epidermic bases (little or no skin penetration)
- Endodermic bases (moderate skin penetration)
- Diadermic bases (high skin penetration)
Examples of Ointment Bases
- Hydrocarbon bases: hard paraffin, soft paraffin, liquid paraffin
- Vegetable oils: olive oil, castor oil, sesame oil
- Lard
- Lanolin
- Emulsifying base: macrogols, lipoid PEG 200, waxy solid PEG 4000
Soft Paraffin (Vaseline)
- A mixture of hard and liquid paraffin that produces a suitable consistency
- Natural soft paraffin is yellow in color
- Decolorized to obtain white soft paraffin
- Advantages: inert, non-irritant, saturated hydrocarbons, anhydrous, compatible with hydrolysable drugs
Paraffin Substitute (Plastibase)
- Consists of liquid paraffin jelled with high molecular weight polyethylene
- Advantages: maintains ointment-like consistency over a wide temperature range and at high concentrations of solids
- Disadvantages: produces a very soft ointment with certain ingredients, can't be prepared by fusion
This quiz covers the definition, purposes, and components of ointments and semisolid preparations in pharmaceutics. Learn about their uses, active ingredients, and additives.
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