An ointment is a viscous semisolid preparation used topically on a variety of body surfaces. These include the skin and the mucus membranes of the eye (an eye ointment), vagina, anus, and nose. An ointment may or may not be medicated.
Description
The vehicle of an ointment is known as ointment base. The choice of a base depends upon the clinical indication for the ointment, and the different types of ointment bases are:
- Hydrocarbon bases e.g. hard paraffin, soft paraffin
- Absorption bases e.g. wool fat, beeswax
- Water soluble bases e.g. macrogols 200, 300, 400
- Emulsifying bases e.g. emulsifying wax, cetrimide
- Vegetable oils e.g. olive oil, arachis oil, coconut oil
The medicaments are dispersed in the base and later they get divided after the drug penetration into the living cells of skin.
Ointments are homogeneous, semi-solid preparations intended for external application to the skin or mucous membranes. They are used as emollients or for the application of active ingredients to the skin for protective, therapeutic, or prophylactic purposes and where a degree of occlusion is desired.
Ointments are formulated using hydrophobic, hydrophilic, or water-emulsifying bases to provide preparations that are immiscible, miscible, or emulsifiable with skin secretions. They can also be derived from hydrocarbon (fatty), absorption, water-removable, or water-soluble bases.
Evaluation of ointments
- Drug content
- Release of medicament from base
- Medicament penetration
- Consistency of the preparation
- Absorption of medicament into blood stream
- Irritant effect
Properties which affect choice of an ointment base are:
- Stability
- Penetrability
- Solvent property
- Irritant effects
- Ease of application and removal
Methods of preparation of ointments
Trituration: In this finely subdivided insoluble medicaments are evenly distributed by grinding with a small amount of the base followed by dilution with gradually increasing amounts of the base.
Fusion: In this method the ingredients are melted together in descending order of their melting points and stirred to ensure homogeneity.
Topical medication forms
- Cream - Emulsion of oil and water in approximately equal proportions. Penetrates stratum corneum outer layer of skin well.
- Ointment - Combines oil (80%) and water (20%). Effective barrier against moisture loss.
- Gel - Liquefies upon contact with the skin.
- Paste - Combines three agents - oil, water, and powder; an ointment in which a powder is suspended.
- Powder[1]
Bold text==See also==
oinmant are viscous thick (ankit sharma)
References
- ^ "Doctor, why are you prescribing an ointment?"; American Academy of Dermatology
External links
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