Cosolvents parenteral dosage forms

In this chapter, the uses of cosolvents are discussed with some speciLc limitations. The discussion is limited to the cosolvent effects on solubility and stability, their use in parenteral products. For information on the use of cosolvents in other dosage forms such as soft gelatin capsules, the reader is referred to the speciLc chapter in this book on the topic. 

As discussed above, cosolvents can be an effective way to alter the solubility and stability of compounds. In formulating a parenteral product, often these two parameters can be exploited to produce a commercially acceptable, elegant product. Often cosolvents can be used to concentrate a formulation to allow production of a dosage form for presentation as an ampule or vial. The concentrated ampule or vial is then diluted before administration to the patient. Nema et al. [107] has reviewed excipient use, including cosolvents, in commercially available injectable products. 

The choice of solubilization method will depend upon how efficiently the drug can be solubilized, stability in the system, and upon the biocompatibility of the vehicle for a given delivery route. For solid dosage forms, it may be possible to alter the solid phase to enhance dissolution. For parenterals, the four most commonly used techniques for solubilization are pH adjustment cosolvent addition micelle inclusion through surfactant addition and complexation. The following chapter is designed to summarize the theoretical as well as practical use of each of the above techniques. More extensive discussion on techniques for drug solubilization can be found in books dedicated to the subject. ... 

---