![]() ![]() Creaming: Creaming is the migration of the droplets of the internal phase to the top or bottom of the emulsion. Surfactants and emulsifying agents commonly used for compounding purposes are described and discussed in Chapter 20, Surfactants and Emulsifying Agents.Į. Some emulsifying agents also increase the viscosity of the system, slowing aggregation of the droplets and decreasing the rate of creaming. ![]() Emulsifying agents: Emulsifying agents are surfactants that concentrate at the interface of the two immiscible phases, reduce the interfacial tension between the immiscible phases, provide a barrier around the droplets as they form, and prevent coalescence of the droplets. The dispersed droplets are collectively termed the internal phase, and the continuous liquid is called the external phase.ĭ. This is accomplished by the use of emulsifying agents. It can be accomplished when energy is applied to the system (e.g., trituration or homogenization) to create small droplets and cause a physical and/or electrostatic barrier to form around the droplets to prevent them from coalescing. Emulsification: Emulsification is the process of creating an emulsion from two immiscible liquid phases. Specific miscibility information for common pharmaceutical solvents is given in Chapter 15, Pharmaceutical Solvents and Solubilizing Agents for a general discussion of miscibility, see section IV. Immiscible liquid pairs are imperceptibly soluble in each other in any proportion examples include water and mineral oil, and alcohol and mineral oil. Some liquid pairs, such as castor oil and alcohol, are partially miscible, which means that they are soluble in each other in definite proportions. Miscible/immiscible: When two liquids are completely soluble (that is, molecularly dispersed) in each other in all proportions, they are said to be miscible examples include water and alcohol, and olive oil and cottonseed oil. Liniment: “A solution or mixture of various substances in oil, alcoholic solutions or soap, or emulsions intended for external application” ( 2).ī. A footnote states that this term will be restricted to emulsions and will no longer be used for solutions or suspensions ( 2).ī. This dosage form is generally for external application to the skin” ( 2). Lotion: “An emulsion, liquid dosage form. According to the 2006 FDA CDER Data Standards Manual, the following definitions apply:Ī. In 2006, FDA revised its dosage form terminology to help users of drug products in differentiating between topical dosage forms such as lotions, creams, ointments, and pastes ( 2). As was discussed in Chapter 27, in 2002, USP formed a group to clarify pharmaceutical dosage form nomenclature. It should be noted that general terms, such as lotion, liniment, and liquid, have been used to name topical liquids, which could be solutions, suspensions, or emulsions. This chapter covers liquid emulsions semisolid emulsions are discussed in Chapter 30, Semisolids: Ointments, Creams, Gels, Pastes, and Collodions.Ģ. All emulsions for oral administration are liquids, but emulsions for topical administration may be either liquid or semisolid. Emulsions: “Emulsions are two-phase systems in which one liquid is dispersed throughout another liquid in the form of small droplets” ( 1).ġ. Special Labeling Requirements for EmulsionsĪ. Compatibility, Stability, and Beyond-Use Dating
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