Excipients for Delivery of Water-Insoluble Agents

This strategy has limitations when the solubility (S) of the neutral drug molecule is very low. For an acidic drug molecule, an increase of one pH unit above the 

Dispersed systems, such as emulsions, have also been employed to achieve high drug loading for parenteral administration. Emulsions generally consist of a vegetable oil (e.g., soybean), a phospholipid surfactant (e.g., lecithin), and glycerol added for isotonicity. The surfactant (emulsifier) is necessary to provide a barrier to agglomeration of the emulsion droplets. Unlike micellar solutions that are thermodynamically stable, 

Suspensions offer another dispersed platform for delivery of poorly water-soluble agents. As compared with solutions, suspensions afford higher loading. However, as with emulsions, the suspended particles must be stabilized with surfactants to prevent aggregation. A number of steroids have been available for years as suspensions for IM and intra-articular delivery. Examples include DEPO-MEDROL (Pfizer, Kalamazoo, Michigan, U.S.A.) Sterile Aqueous Suspension. The marketed product contains methylprednisolone acetate, a white, water-insoluble, crystalline 

The principles of particle stabilization are even more critical to the stabilization of very small solid particles, less than one micron in diameter (e.g., nanosuspensions), which have much greater surface area. The Ostwald-Freundlich equation, 

CONTAINER-EXCIPIENT INTERACTIONS IN INJECTABLE DOSAGE FORMS 

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