Chemical Substances And Its Effects On The Skin

1730 Words May 5th, 2016 7 Pages
Based on United State Pharmacopeia, pastes are defined as semisolid dosage forms that contain one or more drug substances intended for topical application. (Pharmaceutical Dosage Form, 2009) Pastes are also intended for application to oral cavity or mucous membranes besides the skin. Pastes are usually prepared from fats, fatty oils, petrolatum, paraffin, waxes, glycerin or water by mixing homogeneously powdered drug with the foregoing materials as bases. (General Requirements for Pharmaceutical Preparation) There are two classes of paste which are fatty pastes and non-greasy pastes which is made from single phase aqueous gel.
Although the preparations of pastes are similar to ointment, there are still having differences between paste and ointment. Compared to ointments and gels, pastes contain a high proportion of finely powdered medicaments. Pastes are generally composed of ointment bases that contain a high concentration (frequently 50%w/w) of dispersed drug. Hence, the viscosity of pastes is higher than that of pharmaceutical ointment. The base for pastes may be anhydrous (liquid or soft paraffin) or water soluble (glycerol or mucilage). (Prashant, 2010)
Furthermore, pastes take some advantages over the ointments. Pastes are more often used for protective action compared to ointments. This is because pastes ordinarily do not flow at body temperature so it can serve as protective coatings. Fatty pastes that have a high proportion of hydrophilic solids…
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