Food additives Europe numbers: E905a
Applications in Pharmaceutical Formulation:
Mineral oil is used primarily as an excipient in topical pharmaceutical formulations, where its emollient properties are exploited as an ingredient in ointment bases; see Table I. It is additionally used in oil-in-water emulsions,(1–5) as a solvent, and as a lubricant in capsule and tablet formulations, and to a limited extent as a mold release agent for cocoa butter suppositories. It has also been used in the preparation of microspheres and as a vaccine adjunct.(6–10) Therapeutically, mineral oil has been used as a laxative, see Section 14. It is indigestible and thus has limited absorption. Mineral oil is used in ophthalmic formulations for its lubricant properties. It is also used in cosmetics and some food products.(11)
Description
Mineral oil is a transparent, colorless, viscous oily liquid, without fluorescence in daylight. It is practically tasteless and odorless when cold, and has a faint odor of petroleum when heated.
Stability and Storage Conditions
Mineral oil undergoes oxidation when exposed to heat and light. Oxidation begins with the formation of peroxides, exhibiting an ‘induction period’. Under ordinary conditions, the induction period may take months or years. However, once a trace of peroxide is formed, further oxidation is autocatalytic and proceeds very rapidly. Oxidation results in the formation of aldehydes and organic acids, which impart taste and odor. Stabilizers may be added to retard oxidation; butylated hydroxyanisole, butylated hydroxytoluene, and alpha tocopherol are the most commonly used antioxidants. Mineral oil may be sterilized by dry heat. Mineral oil should be stored in an airtight container, protected from light, in a cool, dry place.
Incompatibilities
Incompatible with strong oxidizing agents.
Safety
Mineral oil is used as an excipient in a wide variety of pharmaceutical formulations; see Section 16. It is also used in cosmetics and in some food products. Therapeutically, mineral oil has been used in the treatment of constipation, as it acts as a lubricant and stool softener when taken orally. Daily doses of up to 45 mL have been administered orally, while doses of up to 120 mL have been used as an enema. However, excessive dosage of mineral oil, either orally or rectally, can result in anal seepage and irritation, and its oral use as a laxative is not considered desirable. Chronic oral consumption of mineral oil may impair the appetite and interfere with the absorption of fat-soluble vitamins. Prolonged use should be avoided. Mineral oil is absorbed to some extent when emulsified and can lead to granulomatous reactions. Similar reactions also occur upon injection of the oil;(12) injection may also cause vasospasm. The most serious adverse reaction to mineral oil is lipoid pneumonia caused by aspiration of the oil.(13,14) Mineral oil can enter the bronchial tree without eliciting the cough reflex.(15) With the reduction in the use of mineral oil in nasal formulations, the incidence of lipoid pneumonia has been greatly reduced. However, lipoid pneumonia has also been associated with the use of mineral oil-containing cosmetics(16) and ophthalmic preparations.(17) It is recommended that products containing mineral oil not be used in very young children, the elderly, or persons with debilitating illnesses. Given its widespread use in many topical products, mineral oil has been associated with few instances of allergic reactions. The WHO has not specified an acceptable daily intake of mineral oil given the low concentration consumed in foods.(18) LD50 (mouse, oral): 22 g/kg(19)