Water-in-oil creams

As it turns out, there are pharmaceutical implications associated with the polymorphism of glycerol esters, since phase transformation reactions caused by the melting and solidification of these compounds during formulation can have profound effects on the quality of products. For instance, during the development of an oil-in-water cream formulation, syneresis of the aqueous phase was observed upon using certain sources of glyceryl monostearate [13]. Primarily through the use of variable temperature X-ray diffraction, it was learned that... 

Emulsifying agents provide homogeneous, stable preparations when mixtures of immiscible liquids such as oil-in-water creams are compounded. Some patients develop irritation from these agents. Substituting a preparation that does not contain them or using one containing a lower concentration may resolve the problem. 

Rafiee-Tehrani M, Mehramizi A. In vitro release studies of piroxicam from oil-in-water creams and hydroalcoholic gel topical formulations. Drug Dev Ind Pharm 2000 26(4) 409-414. 

Another example for the importance of the solubility of the drug is corticosteroids. The different photosensitivities of three marketed hydrocortisone oil-in-water creams as shown in Figure 19, is due to the drug concentration as well as the composition of the preparation. Similar degradation rates were found for creams with triamcinolone-acetonid and betamethasone esters (47). 

Vehicles (bases ) are designed to vary in the extent to which they increase the hydration of the stratum comeum e.g. oil-in-water creams promote hydration (see below). Some vehicles also contain substances intended to enhance penetration, e.g. squalane (p. 306). 

Oil-in-water creams, for topical use, generally contain mixed emulsifiers/surfactants one of which is a water soluble surfactant with a high HLB, the other being an amphiphile, usually a long chain fatty alcohol (e.g., of chain length C14 to Cig) or acid (e.g., palmitic or stearic). The water soluble surfactant may be anionic (e.g., sodium lauryl sulphate), cationic (e.g., cetri-mide), or non-ionic (e.g., cetomacrogol. Tweens). 

O Laughlin R, Sachs C, Brittain H, et al. Effects of variations in physicochemical properties of glyceryl monostearate on the stability of an oil-in-water cream. ] Soc Cosmet Chem 1989 40 215-229. 

Tanaka S, Takashima Y, Murayama H, Tsuchiya S. Solubility and distribution of dexamethasone acetate in oil-in-water creams and its release from the creams. Chem Pharm Bull 1985 33 3929— 3934. 

Mineral oil and lanolin alcohols is an oily liquid used in topical pharmaceutical formulations and cosmetics as an emulsifying agent with emollient properties see Table I. It is used as a primary emulsifier in the preparation of water-in-oil creams and lotions and as an auxiliary emulsifier and stabilizing agent in oil-in-water creams and lotions. 

The most common emulsions used in dermatological therapy are creams. These are two-phase preparations in which one phase (the dispersed or internal phase) is finely dispersed in the other (the continuous or external phase). The dispersed phase can be either hydrophobic based (oil-in-water creams, O/W) or aqueous based (water-in-oil creams, W/O). Whether a cream is O/W or W/O is dependent on the properties of the system used to stabilize the interface between the phases. Given the fact that there are two incompatible phases in close conjunction, the physical stability of creams is always tenuous, but may be maximised by the judicious selection of an appropriate emulsion stabilizing system. In most pharmaceutical emulsions, stabilizing systems are comprised of either surfactants (ionic and/or non-ionic), polymers (non-ionic polymers, polyelectrolytes or biopolymers) or mixtures of these. The most commonly used surfactant systems are sodium alkyl sulphates (anionic), alkylammonium halides... 

Chowhan and Pritchard (1978) studied the penetration of naproxen from oil-in-water cream vehicles through human, rat, and rabbit skins. If naproxen in the oil-in-water cream, which was adjusted to pH 7.5, ionizes the same as it would in aqueous solution, then essentially all of the naproxen would be ionized. Based on the in vitro... 

Liquid Liquid Emulsion Milk, water in oil, oil in water, cream. 

These include, for example, sulphated castor oil (triglyceride of the fatty acid 12-hydroxyoleic acid). This is used as an emulsifying agent for oil-in-water creams and ointments (non-irritant). 

These are prepared by treating fixed oils, for example castor oil, (which contains the triglyceride of the fatty acid 12-hydroxyoleic acid) with sulphuric acid and neutralizing with sodium hydroxide solution. Sulphated castor oil is used pharmaceutically as an emulsifying agent for oil-in-water creams and ointments. It is non-irritant and is used as a cleansing agent when soap is contra-indicated. It is also used in the manufacture of shampoos and deodorant sprays. 

All compounds that we have studied for effects on keratinization have been initially evaluated on a series of over twenty patients with ichthyosis of several types. Many of the compounds have been evaluated for therapeutic effects on larger series of patients with dry skin several have been used therapeutically for comedonous acne and a few have been used in therapy of a diverse group of disorders including palmar and plantar hyperkeratosis, Darier s disease, lichen simplex chronicus and others. Reduction in stratum corneum accumulation has been readily demonstrable in all disorders in response to two-four times daily topical application of the compounds formulated as 5-20% oil-in-water creams, as solutions and as gels. 

Uses Emulsifier for water-in-oil creams and lotions protective cream, cleansing lotion, night cream, sunscreen cream, baby cream, dry skin cream and lotion, moisturizing cream, foundation, hand and body cream and lotion coemulsifier for oil-in water creams and lotions conditioner in clear 2-in-1 shower gels and shampoos... 

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