Pharma Talk #6

Hello, friends, today I'll discuss about the importance of various bases used in manufacturing of ointments which is one type of semi-solid dosage form. Additionally, I'll explain structure of skin in tutorials briefly which you must know while studying this type of dosage form. Before that you must have knowledge about transdermal drug delivery system, according to which, it is such a system which delivers the drug through the skin portal to the systemic circulation while maintaining effective concentration over a prolonged period of time. The main importance is to avoid GI obstructions and intestinal complications, though, it is an old fashioned delivery system introduced in 1880. However, the basic principle lies behind the preparation of semi-solid dosage form is introduction of bases which ultimately act as a vehicle along with drugs.These bases should be compatible with drugs otherwise drugs will not be absorbed well topically leading to ultimate failure. There are four bases categorized and as follows,
1. OLEAGINOUS (HYDROCARBON) BASE: 
A. These bases are immiscible with water means difficult to wash off.
B. They are not absorbed by the skin, remained on the skin for prolonged period of time without "drying out".
C. They inhibit water loss from the skin by forming "occlusive dressings".
D. They improve hydration, might encourage penetration of the medication through the skin.
Examples: Vaseline, Liquid paraffin, White paraffin, White ointment
Uses: Protectants, emolient and vehicles for solid drugs.
2. ABSORPTION BASE: 
A.They are less occlusive as compared with the hydrocarbon bases.
B. They can be easily incorporated with aqueous solution.
C. They spread easily over the area as they absorb fluently.
D. Good emolient property but not much as compared to oleaginous base.
E. They hydrate the stratum corneum and are difficult to wash off because bases are oily in nature.
F. They are W/O emulsion type.
Uses: Protectants, emolient and vehicles for solid and liquid drugs.

3. WATER REMOVABLE BASES: 
A. They are easily washed from the skin
B. They are less greasier as well as occlusive as compared to oleaginous bases.
C. They are used for better compliance as patients prefer creams over ointment because creams readily spread, less greasy, and evaporating water soothes the inflamed tissue.
Examples: cleansing creams, emolients and vehicles for solid and liquid drugs.
4. WATER SOLUBLE BASES:
A. As they do not contain oleaginous component.
B. They are water soluble and water washable.
Example: drug vehicles
I think I have covered all the bases used in preparation of ointement, if you want to know detailed preparation of these bases then let me know in the comment section until then stay healthy and make others too.

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