Three-component Pharmaceutical Solids

1 Chiral and Racemic Co-crystals and Co-crystal-Co-crystal Reactions 

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A pharmaceutical cocrystal is composed of an API and complementary molecules including excipients (non-toxic ingredients) or other APIs. Cocrystals may include two or more different components and in most cases to date, two and three component systems are reported with the latter being mostly cocrystalline solvates, e.g., theophylline 5-fluorouracil hydrate. Table 1 presents some examples of pharmaceutical cocrystals and solvates. The term cocrystal generally refers to components that in their pure states are solids at room temperature. It is important to note that a... 

The separation of enantiomers is especially important in the pharmaceutical field, because drag enantiomers may produce different effects in the body. Enantiomer separations by chromatography require one of the components of the phase system to be chiral. This can be achieved by (a) the addition of a chiral compound to the mobile phase, which is then used in combination with a nonchiral stationary phase, or (b) the use of a chiral stationary phase in combination with a nonchiral mobile phase. The chiral phase can either be a solid support physically coated with a chiral stationary phase liquid or a chemically bonded chiral phase. For mobile-phase compatibility reasons, a chiral stationary phase is preferred in LC-MS. However, most chiral stationary phases have stringent demands with respect to mobile-phase compositiorr, which in turn may lead to compatibility problems. Three types of phase systems are applied in LC-MS ... 

On the other hand, elucidation of the typical components and different forms of the physical. systems that we call pharmaceutical suspensions requires previously to have an idea about the different types of suspensions, intimately related to their purpose and applications. Thus, most authors consider three main kinds of pharmaceutical suspensions (4-6). namely, orally administered, or. simply oral, suspensions externally applied (topical suspensions) and injectable or parenteral. Although strictly speaking, from the colloid science point of view, aerosols ore simply suspensions in which the dispersion medium is a gas and the di.spersed material is. solid, throughout this chapter we will primarily adhere to the more clussicul point of view that considers only solid/liquid dispersions under the denomination of suspensions. Their most significant features are displayed in Table I (see also Refs. 4-6). 

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