Petrolatum formulated

The streamer phase observed with neat petrolatum (Figure 28.6[a]) was not observed, but amorphous material was common (data not shown). Reasonable lamellae were occasionally encountered, as shown in Figure 28.6(b). Often these lamellae were separated by thin expanses of amorphous material, as shown in the center of Figure 28.6(b). In general, treatment with formulated petrolatum resulted in an appearance of the intercellular lipids that was much improved over that of neat petrolatum or mineral oil. The corneocytes were more closely apposed, and Landmann units were more common. 

In the fusion method for ointments, mineral oil, petrolatum, waxes, and other ingredients that belong in the formulation are heated together to somewhere... 

Emollients are often added to cream formulations to modify either the characteristics of the pharmaceutical vehicle or the condition of the skin itself to promote penetration of the active ingredient to act either locally or systemically. The stratum corneum, being keratinized tissue, behaves as a semipermeable artificial membrane, and drug molecules can penetrate by passive diffusion. The rate of drug movement depends on the drug concentration in the vehicle, its aqueous solubility, and the oil/ water partition coefficient between the stratum corneum and the product s vehicle. Commonly used emollients include glycerin, mineral oil, petrolatum, isopropyl pal-mitate, and isopropyl myristate. 

Ointment An unctuous semisolid for topical application. Typical ointments are based on petrolatum. An ointment does not contain sufficient water to separate into a second phase at room temperature. Water soluble ointments may be formulated with polyethylene glycol. 

Another very practical and useful method for evaluating skin moisturizers is by the direct measurement of TEWL on human skin.23 Not surprisingly, several studies that incorporate this test method have proven that petrolatum is an excellent moisturizer.24"26 It should be noted that in many studies on TEWL, petrolatum is used as a positive standard when evaluating other cosmetic emollients, since petrolatum is nearly always the most occlusive TEWL barrier material tested. It is often the standard by which other ingredients and formulations are judged. 

Most investigations on skin moisturization evaluate petrolatum alone. The moisturizing efficacy of a petrolatum-containing cream was reported by Prall and coworkers in one study and compared with those of two other creams, one containing urea and one containing alpha-hydroxy acids.30 In both cases, the petrolatum-containing product was found to be comparable to the other formulations as judged by skin dryness. 

Diapers are related products that also benefit similarly from the addition of emollients such as petrolatum. Petrolatum can not only reduce the adherence of bodily waste to the skin but also provide emolliency.103-107 When applied to the cuffs of diapers, petrolatum also imparts lubricity and minimizes abrasion on the skin.108 Finally, petrolatum has been formulated into an emulsion that is applied to various cleansing wipes (e.g., baby wipes).109... 

FIGURE 28.6 (a) Neat petrolatum site from a 42-year-old male. Flocculent/fibrous material existing as streamers or bands is present within an otherwise empty-appearing intercellular space, (b) Formulated (10%) petrolatum site. Lamellae, occasionally forming Landmann units, are sometimes separated by a thin layer of more darkly staining amorphous material. Bar = 200 nm. 

To conclude this section, previous reports on the beneficial effects of topically applied moisturizing preparations have often focused on optimizing their physiological lipid composition. The results found for the formulated SEFA and petrolatum in this work, when viewed relative to the neat materials, suggest that proper formulation of even nonphysiological moisturizing agents will enhance the beneficial effect these materials have on outer SC lipid structure. 

Selection of an appropriate base for an ointment or cream formulation depends on the type of activity desired (e.g., topical or percutaneous absorption), compatibility with other components, physicochemical and microbial stability of the product, ease of manufacture, pourability and spreadability of the formulation, duration of contact, chances of hypersensitivity reactions, and ease of washing from the site of application. In addition, bases that are used in ophthalmic preparations should be nonirritating and should soften at body temperatures. White petrolatum and liquid petrolatum are generally used in ophthalmic preparations. Table 1 summarizes... 

The effect of ophthalmic ointments on the healing of corneal wounds has been studied. Early formulations of ophthalmic ointments contained waxy grades of petrolatum or imwashed lanolin, which interfered with corneal woimd heahng. Contemporary ophthalmic ointments, however, are nonemulsive and do not contain the coarse grade of white petrolatum. These ointments cause no significant inhibition of corneal woimd healing. 

Yellow ointment, USP—the purified wax obtained from the honeycomb of the bee. It contains 5% yellow wax and 95% petrolatum in the formulation. 

Odio MR, O Connor RJ, Sarbaugh F, Baldwin S. Continuous topical administration of a petrolatum formulation by a novel disposable diaper. 2. Effect on skin condition. Dermatology 2000 200(3) 238M3. 

Glucocorticoid contact allergy is well known (SEDA-21, 158) and has to be particularly suspected in chronic conditions affecting the perianal area (17), after long-term topical medication, and in cases of failure to ameliorate dermatitis with corticosteroids. Patch tests should then be performed both with the recommended markers, budeso-nide (0.1% petrolatum) and tixocortol pivalate (1% petrolatum), and with the patient s own formulations. 

Cetyl alcohol is also used for its water absorption properties in water-in-oil emulsions. For example, a mixture of petrolatum and cetyl alcohol (19 1) will absorb 40-50% of its weight of water. Cetyl alcohol acts as a weak emulsifier of the water-in-oil type, thus allowing a reduction of the quantity of other emulsifying agents used in a formulation. Cetyl alcohol has also been reported to increase the consistency of water-in-oil emulsions. 

Lanolin alcohols is used in topical pharmaceutical formulations and cosmetics as a hydrophobic vehicle with emollient properties, e.g., in preparations for dry skin and dry eyes. It is also used in the preparation of water-in-oil creams and ointments at concentrations as low as 2% w/w. The proportion of water that can be incorporated into petrolatum is increased threefold hy the addition of 5% lanolin alcohols. Such emulsions do not crack upon the addition of citric, lactic, or tartaric acids. 

Petrolatum is mainly used in topical pharmaceutical formulations as an emollient-ointment base it is poorly absorbed by the skin. Petrolatum is also used in creams and transdermal formulations and as an ingredient in lubricant formulations for medicated confectionery together with mineral oil. 

Petrolatum is mainly used in topical pharmaceutical formulations and is generally considered to be a nonirritant and nontoxic material. 

Various grades of petrolatum are commercially available, which vary in their physical properties depending upon their source and refining process. Petrolatum obtained from different sources may therefore behave differently in a formulation. Care is required in heating petrolatum because of its large coefficient of thermal expansion. It has been shown by both rheological and spectrophotometric methods that petrolatum undergoes phase transition at temperatures between 30—40°C. 

Barker G. New trends in formulating with mineral oil and petrolatum. 

De Muynck C, Lalljie SPD, Sandra P, et al. Chemical and physicochemical characterization of petrolatums used in eye ointment formulations. / Pharm Pharmacol 1993 45 500—503. 

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