Pastes
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Pastes are semisolid dosage forms that contain a large proportion of solid component.
Pastes
Pastes
are semisolid dosage forms that contain a large proportion of solid component.
They differ from ointments in their consistency, as they contain larger amounts
of solids and consequently are thicker and stiffer. Pastes can be made either
of fatty bases, such as petrolatum and hydrophilic petrolatum, or of aqueous
gels, such as celluloses. Pastes may contain one or more drug substances
intended for topical application.
Pastes
are well adsorbed on the skin. Pastes can absorb watery solu-tions so that they
can be used around oozing lesions. Pastes can be easily removed from skin and
are water washable, which is an important consid-eration when they are applied
on traumatized skin.
Pastes
that contain hydrophobic components can be water impermeable and prevent
dehydration. Examples of pastes include the commonly used tooth-pastes and zinc
oxide paste. Toothpaste contains an abrasive solid for cleansing purposes and
sometimes also includes a fluoride salt, such as sodium fluoride or stannous
fluoride, as a medicament. Zinc oxide paste is typically composed of 25% w/w zinc
oxide, 25% w/w starch, and 50% w/w white petrolatum.
Pastes
can be formed from several bases, such as gelatin, starch, traga-canth,
polyethylene glycol, pectin, or cellulose derivatives.
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