Food additives Europe numbers: E905b
Functional Category
Emollient; ointment base.
Applications in Pharmaceutical Formulation
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. Therapeutically, sterile gauze dressings containing petrolatum may be used for nonadherent wound dressings or as a packing material.(1) Petrolatum is additionally widely used in cosmetics and in some food applications
Description
Petrolatum is a pale yellow to yellow-colored, translucent, soft unctuous mass. It is odorless, tasteless, and not more than slightly fluorescent by daylight, even when melted.
Stability and Storage Conditions
Petrolatum is an inherently stable material owing to the unreactive nature of its hydrocarbon components; most stability problems occur because of the presence of small quantities of impurities. On exposure to light, these impurities may be oxidized to discolor the petrolatum and produce an undesirable odor. The extent of the oxidation varies depending upon the source of the petrolatum and the degree of refinement. Oxidation may be inhibited by the inclusion of a suitable antioxidant such as butylated hydroxyanisole, butylated hydroxytoluene, or alpha tocopherol. Petrolatum should not be heated for extended periods above the temperature necessary to achieve complete fluidity (approximately 708C). See also Section 18. Petrolatum may be sterilized by dry heat. Although petrolatum may also be sterilized by gamma irradiation, this process affects the physical properties of the petrolatum such as swelling, discoloration, odor, and rheological behavior.(6,7) Petrolatum should be stored in a well-closed container, protected from light, in a cool, dry place.
Incompatibilities
Petrolatum is an inert material with few incompatibilities.
Safety
Petrolatum is mainly used in topical pharmaceutical formulations and is generally considered to be a nonirritant and nontoxic material. Animal studies, in mice, have shown petrolatum to be nontoxic and noncarcinogenic following administration of a single subcutaneous 100 mg dose. Similarly, no adverse effects were observed in a 2-year feeding study with rats fed a diet containing 5% of petrolatum blends.(9) Although petrolatum is generally nonirritant in humans following topical application, rare instances of allergic hypersensitivity reactions have been reported,(10–12) as have cases of acne, in susceptible individuals following repeated use on facial skin.(13) However, given the widespread use of petrolatum in topical products, there are few reports of irritant reactions. The allergic components of petrolatum appear to be polycyclic aromatic hydrocarbons present as impurities. The quantities of these materials found in petrolatum vary depending upon the source and degree of refining. Hypersensitivity appears to occur less with white petrolatum and it is therefore the preferred material for use in cosmetics and pharmaceuticals. Petrolatum has also been tentatively implicated in the formation of spherulosis of the upper respiratory tract following use of a petrolatum-based ointment packing after surgery,(14) and lipoid pneumonia following excessive use in the perinasal area.(15) Other adverse reactions to petrolatum include granulomas (paraffinomas) following injection into soft tissue.(16) Also, when taken orally, petrolatum acts as a mild laxative and may inhibit the absorption of lipids and lipid-soluble nutrients. Petrolatum is widely used in direct and indirect food applications. In the USA, the daily dietary exposure to petrolatum is estimated to be 0.404 mg/kg body-weight.(17) For further information see Mineral Oil and Paraffin.