Hydrophobic Cream Case Study

1.4.2 Creams :-

Creams are homogenous, semisolid preparations having an opaque emulsion system. Their consistency depends on type of emulsion either (o/w) or an (w/o).They are intended for application to skin or to other membranes.

1.4.2.1Hydrophobic creams (w/o) :-

Hydrophobic creams are usually anhydrous and absorb only small amounts of water. They contain w/o emulsifying agents like wool fat, sorbitan esters, and monoglycerides.

1.4.2.2 Hydrophilic creams (o/w) :-

Hydrophilic creams contain bases that are miscible with water. They also contain o/w emulsifying agents such as sodium or triethanolamine soaps, sulphated fatty alcohols, and polysorbates combined, if necessary, with w/o emulsifying agents.

1.4.3 Ointment :-

They are homogenous

The U.S.P. defines gels as a semisolid system consisting of dispersion made up of either small inorganic particle or large organic molecule enclosing and interpenetrated by liquid. Gels consist of two phase system in which inorganic particles are not dissolved but merely dispersed throughout the continuous phase and large organic particles are dissolved in the continuous phase, randomly coiled in the flexible chains.

Classification of gels:-

1. Based on colloidal phases :-

i) Two phase system :- In this phase the sizes of the dispersed phase are relatively large and form the three dimensional structure throughout gel, such a system consists of floccules of small particles rather than larger molecules and gel structure. ii) Single phase system :- These consist of large organic molecules dissolved in a continuous phase.

2. Based on nature of solvent

i) Hydro gels (water based)