Recent Advances in Formulation Strategies for Efficient Delivery of Vitamin D.

Deficiency of vitamin D is a global concern affecting a huge number of human populations. This deficiency has a serious impact on human health not only affecting bone mineral density but also becoming the reason for cardiovascular disorders, infectious diseases, autoimmune diseases and cancers. Exposure to sunlight is the major source of vitamin D, but due to the present day-to-day lifestyle of working in a shade arouses the need for exogenous sources of vitamin D. Ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) are the two major forms of vitamin D, which are hydrophobic in nature and highly susceptible to environmental conditions, like temperature and light. Therefore, novel drug delivery systems could be explored for efficient delivery of vitamin D. In this review, a brief account of vitamin D is provided followed by a detailed description of recent advances in various delivery systems, including solid lipid nanoparticles, nanoemulsion, self-emulsifying drug delivery systems, polymeric nanoparticles and solid dispersion, for the efficient delivery of vitamin D.

Third Generation Solid Dispersion-Based Formulation of Novel Anti-Tubercular Agent Exhibited Improvement in Solubility, Dissolution and Biological Activity.

The long treatment period and development of drug resistance in tuberculosis (TB) necessitates the discovery of new anti-tubercular agents. The drug discovery program of the institute leads to the development of an anti-tubercular lead (IIIM-019), which is an analogue of nitrodihydroimidazooxazole and exhibited promising anti-tubercular action. However, IIIM-019 displays poor aqueous solubility (1.2 µg/mL), which demands suitable dosage form for its efficient oral administration. In the present study, third generation solid dispersion-based formulation was developed to increase the solubility and dissolution of IIIM-019. The solubility profile of IIIM-019 using various polymeric carriers was determined and subsequently, PVP K-30 and P-407 were selected for preparation of binary and ternary solid dispersion. The third-generation ternary solid dispersion comprising PVP K-30 and P-407 revealed a remarkable enhancement in the aqueous solubility of IIIM-019. Physicochemical characterization of the developed formulations was done by employing FTIR spectroscopy, scanning electron microscopy, X-ray diffraction analysis, differential scanning calorimetry, and dynamic light scattering analysis. The dissolution study indicated an impressive release profile with the optimized formulation. The optimized formulation was further examined for cytotoxicity, cellular uptake, and hemolytic activity. The results indicated that the formulation had no apparent cytotoxicity on Caco-2 cells and was non-hemolytic in nature. Moreover, the optimized formulation showed significantly improved anti-tubercular activity compared to the native molecule. These findings showed that the developed third generation ternary solid dispersion could be a promising option for the oral delivery of investigated anti-tubercular molecule.

Sustained release polymer and surfactant based solid dispersion of andrographolide exhibited improved solubility, dissolution, pharmacokinetics, and pharmacological activity.

Andrographolide (AD) is a potent natural product with a wide range of pharmacological activities. However, it has low oral bioavailability due to poor solubility and dissolution rate. Solid dispersion (SD) is a promising technique to improve the solubility and dissolution rate of such molecules. In this study, SD formulation of AD was prepared using Kollidon-SR (KSR) and Poloxamer-407 (P-407) as carriers. SD was prepared using the solvent evaporation method and evaluated for the modulation of solubility of AD. The developed SD formulation was characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR). Further, dissolution rate, yield, drug content, stability, flowability, and pharmacokinetic profile of SD were evaluated. The compatibility of SD with the Caco-2 cells and its impact on the P-glycoprotein (P-gp) mediated efflux was also investigated. Furthermore, carrageenan-induced paw edema, and adjuvant-induced arthritic model were used to evaluate the efficacy of SD. The results showed that SD3 (AD + KSR + P-407, 1:6:8) exhibited the highest solubility and dissolution rate, and significantly improved pharmacokinetic profile compared to native AD. SD3 was found to be stable during storage and displayed excellent yield, drug content, and flowability. This formulation was found to be compatible with the Caco-2 cells and retarded the efflux of P-gp substrate. SD3 also demonstrated substantially better efficacy than native AD in terms of paw edema inhibition (carrageenan-induced paw edema, Wistar rats), and overall improvement of disease condition (in terms of paw edema, arthritic score, AST, ALT, cytokines, radiological changes, and histopathology) in arthritic Wistar rats. In conclusion, SD3 exhibited improved solubility, dissolution rate, pharmacokinetic profile, and pharmacological activity than native AD.

Redox-Responsive Hyaluronic Acid-Tacrolimus Conjugate: Synthesis, Characterization, and In Vitro Immunosuppressive Activity.

A redox-responsive macromolecular prodrug of tacrolimus, HA-ss-Tac, was constructed by conjugation of tacrolimus (TAC, FK506) through its succinate ester to cystamine-modified hyaluronic acid (HA-Cys), and its physicochemical properties and immunosuppressive activity were studied. The synthesized HA-ss-TAC was determined to contain 8% of chemically loaded TAC with significantly enhanced water solubility. The release study showed a sustained release of drug through slow degradation of linker-drug bonds. In vitro inhibition of proliferation of T- and B-lymphocytes was almost comparable to that of TAC, implying that the biologically active compound could be released from the conjugate. The polymeric prodrug lacks obvious cytotoxicity on Raw 264.7 macrophages and significantly suppressed the production of inflammatory cytokines IL-2 and IL-1ß by LPS-activated cells. Additionally, the cellular uptake study of the FITC-labeled conjugate confirmed the HA receptor-mediated internalization of the conjugate into targeted cells, thus avoiding systemic side effects. Taken together, the HA-ss-TAC prodrug could be an optimal prodrug for intravenous administration based on this preliminary data and can be expected to have improved therapeutic efficacy.

Recent Advances in the Surfactant and Controlled Release Polymer-based Solid Dispersion.

The oral route is the most preferred delivery route for drug administration due to its advantages, such as lower cost, improved patient compliance, no need for trained personnel, and less severity of drug reactions in general. The major problem with new molecules in the drug discovery pipeline is poor solubility and dissolution rate that ultimately results in low oral bioavailability. Numerous techniques are available for solubility and bioavailability (BA) enhancement, but out of all, solid dispersion (SD) is proven to be the most feasible due to fewer issues in manufacturing, processing, storage, and transportation. In the past few years, SD has been extensively applied to reinforce the common issues of insoluble drugs. Currently, many hydrophobic and hydrophilic polymers are used to prepare either immediate release or controlled release SDs. Therefore, the biological behavior of the SDs is contingent upon the use of appropriate polymeric carriers and methods of preparation. The exploration of novel carriers and methodologies in SD technology leads to improved BA and therapeutic effectiveness. Moreover, the clinical applicability of SD-based formulations has been increased with the discovery of novel polymeric carriers. In this review, emphasis is laid down on the present status of recent generations of SDs (i.e., surfactant and controlled release polymer-based SD) and their application in modifying the physical properties of the drug and modulation of pharmacological response in different ailments.

Recent Advances in Solid Dispersion Technology for Efficient Delivery of Poorly Water-Soluble Drugs.

Drug discovery is generally considered as a costly affair and it takes approximately 15 years to reach a new chemical entity into the market. Among the recent potent drug molecules with most effective pharmacological properties, very few reached for Phase I clinical trial in humans. Unfortunately, the historical average reveals an almost 90% overall attrition rate in clinical trials. The solubility and permeability of a drug are the critical factors influencing the success of a drug. Oral drug delivery systems still continue to exist as the most favored, simplest and easiest administration route. A huge number of potential clinical candidates won't make it to the market or accomplish their maximum capacity except if their solubility and oral bioavailability are enhanced by formulation. The solubility of drugs will continue to exist as important aspects of formulation development. With the emergence of synthetic methods for new molecule synthesis in chemistry and better screening methods, the number of poorly water soluble compounds has dramatically expanded in the last few years. Solid dispersion is one of the most important techniques as it can be prepared by several methods. It is mostly prepared with a drug having poor water solubility and it explores hydrophilic polymers either individually or in combination for the enhancement of solubility. In comparison to the conventional formulations such as tablets or capsules, there are different methods with which solid dispersions can be prepared and also have many benefits over conventional drug delivery approaches. Solid dispersion systems are potential for increasing the solubility, oral absorption and bioavailability of drugs and the significance of the solid dispersion technology is constantly increasing. The main focus of this review is to present recent advancements in the area of solid dispersion. This review also includes an account of recent patents on solid dispersion and clinical status of solid dispersion based formulations.