Researchers have always been fascinated with creating new materials and composites with novel structures and specialized functional capabilities. In the drug discovery process, approximately 90% of the new chemical entities are water-insoluble or low permeable, and about 40% of the market-approved drugs are poorly water-soluble. Limitations related to solubility, stability, drug resistance, and adverse effects of the developed drugs have dug out the opportunity and encouraged focused research on drug delivery systems at the molecular level as targeted drug delivery systems. Scientific advancements and techniques have developed several drug delivery systems. This book comprises chapters authored by various researchers and edited by experts active in the pharmaceutical research area. All the chapters are complete and united under a common research study. This publication aims to provide a thorough overview of the latest research in drug delivery systems and related issues. It also cracked new possible research paths in drug delivery systems for further novel developments.