Just found this interesting chapter of the book "Amorphous Drugs"
by Marzena Rams-Baron, Renata Jachowicz, Elena Boldyreva, Delian Zhou, Witold Jamroz, Marian Plausch
This book explains theoretical and technological aspects of amorphous drug formulations. It is intended for all those wishing to increase their knowledge in the field of amorphous pharmaceuticals. Conversion of crystalline material into the amorphous state, as described in this book, is a way to overcome limited water solubility of drug formulations, in this way enhancing the chemical activity and bioavailability inside the body.
The poor oral bioavailability of many active pharmaceutical ingredients (APIs) resulting from low solubility is one of the important challenges in pharmaceutical technology. Over the last two decades the number of relatively insoluble drugs has grown steadily. Nowadays it is estimated that approximately 70% of new drug candidates are characterized by poor solubility. In order to ensure the optimum therapeutic efficacy, the selection of the drug substance and formulation is crucial in drug design. The development and approval of new, innovative and safe drugs is tremendously complex and requires extensive knowledge of materials, current technological processes and regulations. Bearing in mind that the form of drug should be suitable for the administration route and safe to apply, understanding of manufacturing process is of key importance to successful dosage form development.
During ASDs formulation unpredicted solid state changes of drugs may occur under the influence of different factors such temperature, pressure and moisture. It is the reason why monitoring of phase transformation during technological processing and proper knowledge of the factors determining eventual conversion is important.
For oral drugs containing ASDs the physicochemical properties and dissolution behavior is important to the dissolution rate performance of poorly soluble drugs, Therefore, properly designed dissolution test is a measure of critical quality attri- butes of ASDs composition and physicochemical changes during dissolution as well as upon aging. Significance of factors discussed above such as solubility, dissolution rate, permeability and dose arises from their influence on in vivo performance, drug product assessment as well as determination control quality attributes (CQA). It makes ASDs important in pharmaceutical development due to the need for improvements in manufacturing techniques and the growing number of poorly soluble drug candidates.