Creams are semisolid dosage forms containing one or more drug sub-stances dissolved or dispersed in a suitable o/w or w/o emulsion base.
Creams
Creams
are semisolid dosage forms containing one or more drug sub-stances dissolved or
dispersed in a suitable o/w or w/o emulsion base. Creams are more fluid
compared to other semisolid dosage forms, such as ointments and pastes. Creams
have a whitish, creamy appearance, which is a result of scattering of light
from their dispersed phases, such as oil globules. This distinguishes them from
simple ointments, which are translucent.
Creams
based on o/w emulsions are useful as water-washable bases, whereas w/o
emulsions have emollient and cleansing action. As described earlier, an o/w
cream with high water content is also known as a vanishing cream. Upon rubbing this cream on the skin, the
external/continuous aqueous phase evapo-rates, leading to increased
concentration of a water-soluble drug in the oily film that adheres to the
skin. This increase in the concentration gradient of the drug across the
stratum corneum promotes percutaneous absorption.
Creams
based on w/o emulsions, such as cold
cream, are useful as soft-ening and cleansing agents. The name, cold cream,
refers to the cooling sensation associated with the slow evaporation of the
dispersed aqueous phase. A cold cream, typically, also contains scents and is
used to remove makeup. Other common cold cream components include mineral oil,
jojoba oil, lanolin, glycerin, alcohol, borax, and beeswax in addition to
antimicro-bial preservatives such as methylparaben and propylparaben.
The
use of creams as drug delivery systems is associated with good patient
acceptance. In addition to the general requirements for semisolid dosage forms,
incorporation of drug in a cream requires that the drug should
Be soluble in desired concentration.
·
Have relatively wide therapeutic window since accurate
dosing is difficult.
·
Not crystallize upon evaporation of water.
TH 2019 - 2023 pharmacy180.com; Developed by Therithal info.