Q: A formulation calls for "capric/caprylic triglyceride." What is that?
A: "Capric/caprylic triglyceride" is a synonym for mediumchain triglycerides (MCT), also known as MCT oil, oleum neutrale, oleum vegetable tenue, and thin vegetable oil. It is a colorless or slightly yellow, oily liquid with almost no odor and no taste that solidifies at about 0°C. At low temperatures, it can exhibit high viscosity, and, therefore, it should be warmed before incorporating it into a preparation to ensure miscibility. It should be stored in a filled and closed container at temperatures around 25°C (brief excursions above 40°C will not have a significant deleterious effect). The material is sterilized for use in parenteral preparations by heating to 170°C for 1 hour with suitable equipment. It has a density of approximately 0.95 g/cm3. Brand names include Bergabest, Captex 300, Crodamol GTCC, Neobee M5, and Miglyol 810 and 812. Its Chemical Abstracts Service number is 73398-61-5 and molecular weight is about 500 (avg). The European Pharmacopoeia 2005 describes the material as a fixed oil derived from coconut oil (it also is derived from palm [palm kernel oil]), consisting of a mixture of saturated fatty acids primarily caprylic acid and capric acid. MCT oil is used pharmaceutically as an emulsifying agent, solvent, or suspending agent, and as a therapeutic agent (dietary supplement in fat malabsorption conditions).
In topical preparations, the material helps with emollient and spreading effects without leaving a film, allows skin respiration, and has good penetrating qualities. Rectally, it has been used as a component of suppositories. Parenterally, it has been used with long-chain triglycerides in total parenteral nutrition and as an emulsifier and viscosity-increasing agent. The material is listed as "generally recognized as safe" and is included in the FDA Inactive Ingredients Guide for use in topical preparations. Toxicologically, according to the Handbook of Pharmaceutical Excipients, 5th edition, the material is regarded to be generally nontoxic and nonirritant.
An anhydrous vehicle based on MCT oil has been described (Allen LV Jr. Medium-chain triglycerides oral vehicle, anhydrous. International Journal of Pharmaceutical Compounding. Jan/Feb 2006;10:63). The author notes that assigning a beyond-use date of up to 6 months, when appropriately packaged, is appropriate for this vehicle. It has the advantage of having a slightly sweet taste "somewhat like cake icing."
Mr. Erickson is director of professional affairs at Gallipot Inc.
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