Vitamin polysorbate solubilisation

The polysorbate nonionics have also been employed in the preparation of aqueous injections of the water-insoluble vitamins A, D, E and K. Table 6.14 shows the solubility of these vitamins in 10% polysorbate solutions, polysorbate 20 and 80 being the best two solubilisers. 

Solubilisates are colloidal solutions of a liquid in another liquid that is not miscible with it (see Sect. 18.3.3). The fat-soluble vitamins A, D and E are to be administered as solubilisates to patients with impaired fat absorption, such as patients with cystic fibrosis, to get the vitamins absorbed. Fat-soluble liquid active substances can be solubilised using surfactants, whereby colloidal particles, micelles, are formed. Relatively high concentrations of surfactants are necessary because they have to exceed the critical micelle concentration. Polysorbate 80 (see also Sect. 23.6.4) is... 

Syrups are a very commonly used form of sugars. They contain approximately 45-65 % of sugar, water and a preservative. Sometimes a flavouring is added. The preservative is most often methyl parahydroxybenzoate 0.1-0.15 %. Syrups can be very useful for improving the taste of oral liquid preparations and sometimes they can be used to stabilise a solubilisate of oil and polysorbate, e.g. in a vitamin A micellar solution (Table 23.12). 

One of the best known solubilisations prepared in a pharmacy is that of an oily solution of a vitamin in water. First, polysorbate 80 as a surfactant is mixed with the oil (containing the vitamin). Then it is mixed with sugar syrup by which micelles of polysorbate are formed in which the oil is solubilised (see Sect. 18.3.3). During the mixing little force is used. If mixing is done too intensively, the micelles are broken and a milky product (emulsion) is formed. 

Vitamin E acetate is easily incorporated into cosmetics and has good stability. Vitamin E is soluble in alcohol, fats and oils, and like vitamin A patmitate, can be solubilized in aqueous solutions with solubilisers such as polysorbate 80. Vitamin E acetate can be added to the oil phase of topical formulations without special precautions however, strong alkaline solution will specify the ester. 

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