Role of Fine Silica as Amorphous Solid Dispersion Carriers for Enhancing Drug Load and Preventing Recrystallization- A Comprehensive Review.

Amorphous solid dispersion (ASD) is a popular concept for improving the dissolution and oral bioavailability of poorly water-soluble drugs. ASD faces two primary challenges of low drug loading and recrystallization upon storage. Several polymeric carriers are used to fabricate a stable ASD formulation with a high drug load. The role of silica in this context has been proven significant. Different types of silica, porous and nonporous, have been used to develop ASD. Amorphous drugs get entrapped into silica pores or adsorbed on their surface. Due to high porosity and wide surface area, silica provides better drug dissolution and high drug loading. Recrystallization of amorphous drugs is inhibited by limited molecular ability inside the delicate pores due to hydrogen bonding with the surface silanol groups. A handful of researches have been published on silica-based ASD, where versatile types of silica have been used. However, the effect of different kinds of silica on product stability and drug loading has been rarely addressed. The present study analyzes multiple porous and nonporous silica types and their distinct role in developing a stable ASD. Emphasis has been given to various types of silica which are commonly used in the pharmaceutical industry.

Applications of Nanotechnology-based Approaches to Overcome Multi-drug Resistance in Cancer.

Cancer is one of the leading causes of death worldwide. Chemotherapy and radiation therapy are the major treatments used for the management of cancer. Multidrug resistance (MDR) is a major hindrance faced in the treatment of cancer and is also responsible for cancer relapse. To date, several studies have been carried out on strategies to overcome or reverse MDR in cancer. Unfortunately, the MDR reversing agents have been proven to have minimal clinical benefits, and eventually, no improvement has been made in therapeutic efficacy to date. Thus, several investigational studies have also focused on overcoming drug resistance rather than reversing the MDR. In this review, we focus primarily on nanoformulations regarded as a novel approach to overcome or bypass the MDR in cancer. The nanoformulation systems serve as an attractive strategy as these nanosized materials selectively get accumulated in tumor tissues, thereby improving the clinical outcomes of patients suffering from MDR cancer. In the current work, we present an overview of recent trends in the application of various nano-formulations, belonging to different mechanistic classes and functionalization like carbon nanotubes, carbon nanohorns, carbon nanospheres, liposomes, dendrimers, etc., to overcome MDR in cancer. A detailed overview of these techniques will help researchers in exploring the applicability of nanotechnologybased approaches to treat MDR.

Transdermal Delivery of Macromolecules Using Nano Lipid Carriers.

Skin being the largest external organ, offers an appealing procedure for transdermal drug delivery, so the drug needs to reach above the outermost layer of the skin, i.e., stratum corneum. Small molecular drug entities obeying the Lipinski rule, i.e., drugs having a molecular weight less than 500 Da, high lipophilicity, and optimum polarity, are favored enough to be used on the skin as therapeutics. Skin's barrier properties prevent the transport of macromolecules at pre-determined therapeutic rates. Notable advancements in macromolecules' transdermal delivery have occurred in recent years. Scientists have opted for liposomes, the use of electroporation, low-frequency ultrasound techniques, etc. Some of these have shown better delivery of macromolecules at clinically beneficial rates. These physical technologies involve complex mechanisms, which may irreversibly incur skin damage. Majorly, two types of lipid-based formulations, including Solid Lipid Nanoparticles (SLNs) and Nanostructured Lipid Carriers (NLCs), are widely investigated as transdermal delivery systems. In this review, the concepts, mechanisms, and applications of nanostructured lipid carriers used to transport macromolecules via transdermal routes are thoroughly reviewed and presented along with their clinical perspective.