Drug delivery: an odyssey of 100 years

A Review of Natural Polysaccharides: Sources, Characteristics, Properties, Food, and Pharmaceutical Applications

Natural polysaccharides, which are described in this study, are some of the most extensively used biopolymers in food, pharmaceutical, and medical applications, because they are renewable and have a high level of biocompatibility and biodegradability. The fundamental understanding required to properly exploit polysaccharides potential in the biocomposite, nanoconjugate, and pharmaceutical industries depends on detailed research of these molecules. Polysaccharides are preferred over other polymers because of their biocompatibility, bioactivity, homogeneity, and bioadhesive properties. Natural polysaccharides have also been discovered to have excellent rheological and biomucoadhesive properties, which may be used to design and create a variety of useful and cost-effective drug delivery systems. Polysaccharide-based composites derived from natural sources have been widely exploited due to their multifunctional properties, particularly in drug delivery systems and biomedical applications. These materials have achieved global attention and are in great demand because to their biochemical properties, which mimic both human and animal cells. Although synthetic polymers account for a substantial amount of organic chemistry, natural polymers play a vital role in a range of industries, including biomedical, pharmaceutical, and construction. As a consequence, the current study will provide information on natural polymers, their biological uses, and food and pharmaceutical applications.

Evaluation of Anti-Candida albicans Activity and Release of Ketoconazole in PMMA-G-PEG 4000 Films

Modified release systems depend on the selection of an appropriate agent capable of controlling the release of the drug, sustaining the therapeutic action over time, and/or releasing the drug at the level of a particular tissue or target organ. Polyethylene glycol 4000 (PEG 4000) is commonly employed in drug release formulations while polymethyl methacrylate (PMMA) is non-toxic and has a good solubility in organic solvents. This study aimed at the incorporation of ketoconazole in PMMA-g-PEG 4000 and its derivatives, thus evaluating its release profile and anti-Candida albicans and cytotoxic activities. Ketoconazole was characterized and incorporated into the copolymers. The ketoconazole incorporated in the copolymer and its derivatives showed an immediate release profile. All copolymers with ketoconazole showed activity against Candida albicans and were non-toxic to human cells in the entire concentration tested.

Key Points in Remote-Controlled Drug Delivery: From the Carrier Design to Clinical Trials

The increased research activity aiming at improved delivery of pharmaceutical molecules indicates the expansion of the field. An efficient therapeutic delivery approach is based on the optimal choice of drug-carrying vehicle, successful targeting, and payload release enabling the site-specific accumulation of the therapeutic molecules. However, designing the formulation endowed with the targeting properties in vitro does not guarantee its selective delivery in vivo. The various biological barriers that the carrier encounters upon intravascular administration should be adequately addressed in its overall design to reduce the off-target effects and unwanted toxicity in vivo and thereby enhance the therapeutic efficacy of the payload. Here, we discuss the main parameters of remote-controlled drug delivery systems: (i) key principles of the carrier selection; (ii) the most significant physiological barriers and limitations associated with the drug delivery; (iii) major concepts for its targeting and cargo release stimulation by external stimuli in vivo. The clinical translation for drug delivery systems is also described along with the main challenges, key parameters, and examples of successfully translated drug delivery platforms. The essential steps on the way from drug delivery system design to clinical trials are summarized, arranged, and discussed.

Development and Characterization of Venetoclax Nanocrystals for Oral Bioavailability Enhancement

Venetoclax (VX) used in the treatment of chronic lymphocytic leukemia possesses low oral bioavailability (5.4%) and undergoes first-pass metabolism. Development of a formulation to overcome its bioavailability problem can be done by using nanocrystals which has many scientific applications. Nanocrystals of VX were formulated using amalgamation of precipitation and high-pressure homogenization method, in which polyvinyl alcohol (PVA) was selected as stabilizer. Process parameters like concentration of stabilizer, homogenization pressure, number of homogenization cycle, and concentration of lyoprotectant were optimized to obtain the desired particle size for the preparation of nanocrystal formulation. HPLC methods were developed and validated in-house for determination of in vitro dissolution data and in vivo bioavailability data. Physicochemical characterization was done to determine the particle size (zeta sizer), crystalline nature (DSC and XRPD), solubility (shaker bath), and dissolution (USP type 2 apparatus). Lyophilized VX nanocrystals of size less than 350 nm showed substantial increase in saturation solubility (~20 folds) and dissolution in comparison with free VX. In vitro release study revealed that 100% dissolution was achieved in 120 min as compared to VX free base which is having less than 43.5% dissolution in 120 min. Formulations of VX remain stable for 6 months under accelerated stability conditions. In vivo pharmacokinetic data in male Sprague-Dawley rats showed (~2.02 folds) significant increase in oral bioavailability of VX formulation as compared to free drug because of rapid dissolution and absorption which makes the nanocrystal formulation a better approach for oral administration of poorly soluble drugs.

Anxiety, Depression, and the Microbiome: A Role for Gut Peptides

The complex bidirectional communication between the gut and the brain is finely orchestrated by different systems, including the endocrine, immune, autonomic, and enteric nervous systems. Moreover, increasing evidence supports the role of the microbiome and microbiota-derived molecules in regulating such interactions; however, the mechanisms underpinning such effects are only beginning to be resolved. Microbiota-gut peptide interactions are poised to be of great significance in the regulation of gut-brain signaling. Given the emerging role of the gut-brain axis in a variety of brain disorders, such as anxiety and depression, it is important to understand the contribution of bidirectional interactions between peptide hormones released from the gut and intestinal bacteria in the context of this axis. Indeed, the gastrointestinal tract is the largest endocrine organ in mammals, secreting dozens of different signaling molecules, including peptides. Gut peptides in the systemic circulation can bind cognate receptors on immune cells and vagus nerve terminals thereby enabling indirect gut-brain communication. Gut peptide concentrations are not only modulated by enteric microbiota signals, but also vary according to the composition of the intestinal microbiota. In this review, we will discuss the gut microbiota as a regulator of anxiety and depression, and explore the role of gut-derived peptides as signaling molecules in microbiome-gut-brain communication. Here, we summarize the potential interactions of the microbiota with gut hormones and endocrine peptides, including neuropeptide Y, peptide YY, pancreatic polypeptide, cholecystokinin, glucagon-like peptide, corticotropin-releasing factor, oxytocin, and ghrelin in microbiome-to-brain signaling. Together, gut peptides are important regulators of microbiota-gut-brain signaling in health and stress-related psychiatric illnesses.

Protein based therapeutic delivery agents: Contemporary developments and challenges

As unique biopolymers, proteins can be employed for therapeutic delivery. They bear important features such as bioavailability, biocompatibility, and biodegradability with low toxicity serving as a platform for delivery of various small molecule therapeutics, gene therapies, protein biologics and cells. Depending on size and characteristic of the therapeutic, a variety of natural and engineered proteins or peptides have been developed. This, coupled to recent advances in synthetic and chemical biology, has led to the creation of tailor-made protein materials for delivery. This review highlights strategies employing proteins to facilitate the delivery of therapeutic matter, addressing the challenges for small molecule, gene, protein and cell transport.

Leveraging Physiology for Precision Drug Delivery

Physiological characteristics of diseases bring about both challenges and opportunities for targeted drug delivery. Various drug delivery platforms have been devised ranging from macro- to micro- and further into the nanoscopic scale in the past decades. Recently, the favorable physicochemical properties of nanomaterials, including long circulation, robust tissue and cell penetration attract broad interest, leading to extensive studies for therapeutic benefits. Accumulated knowledge about the physiological barriers that affect the in vivo fate of nanomedicine has led to more rational guidelines for tailoring the nanocarriers, such as size, shape, charge, and surface ligands. Meanwhile, progresses in material chemistry and molecular pharmaceutics generate a panel of physiological stimuli-responsive modules that are equipped into the formulations to prepare “smart” drug delivery systems. The capability of harnessing physiological traits of diseased tissues to control the accumulation of or drug release from nanomedicine has further improved the controlled drug release profiles with a precise manner. Successful clinical translation of a few nano-formulations has excited the collaborative efforts from the research community, pharmaceutical industry, and the public towards a promising future of smart drug delivery.

Impact of preformulation on drug development

INTRODUCTION

Preformulation assists scientists in screening lead candidates based on their physicochemical and biopharmaceutical properties. This data is useful for selection of new chemical entities (NCEs) for preclinical efficacy/toxicity studies which is a major section under investigational new drug application. A strong collaboration between discovery and formulation group is essential for selecting right NCEs in order to reduce attrition rate in the late stage development.

AREAS COVERED

This article describes the significance of preformulation research in drug discovery and development. Various crucial preformulation parameters with case studies have been discussed.

EXPERT OPINION

Physicochemical and biopharmaceutical characterization of NCEs is a decisive parameter during product development. Early prediction of these properties helps in selecting suitable physical form (salt, polymorph, etc.) of the candidate. Based on pharmacokinetic and efficacy/toxicity studies, suitable formulation for Phase I clinical studies can be developed. Overall these activities contribute in streamlining efficacy/toxicology evaluation, allowing pharmacologically effective and developable molecules to reach the clinic and eventually to the market. In this review, the magnitude of understanding preformulation properties of NCEs and their utility in product development has been elaborated with case studies.

Supramolecular core-shell nanosilica@liposome nanocapsules for drug delivery

The fabrication of core-shell structural nanosilica@liposome nanocapsules as a drug delivery vehicle is reported. SiO(2) nanoparticles are encapsulated within liposomes by a W/O/W emulsion approach to form supramolecular assemblies with a core of colloidal particles enveloped by a lipid bilayer shell. A nanosilica core provides charge compensation and architectural support for the lipid bilayer, which significantly improves their physical stability. A preliminary application of these core-shell nanocapsules for hemoglobin (Hb) delivery is described. Through the H-bonding interaction between the hydroxyl groups on nanosilicas and the amino nitrogens of Hb, Hb-SiO(2) nanocomplexes in which the saturated adsorption amount of Hb on SiO(2) is 0.47 g g(-1) are coated with lipids to generate core-shell Hb-SiO(2)@liposome nanocapsules with mean diameters of 60-500 nm and Hb encapsulation efficiency of 48.4-87.9%. Hb-SiO(2)@liposome supramolecular nanovehicles create a mode of delivery that stabilizes the encapsulated Hb and achieves long-lasting release, thereby improving the efficacy of the drug. Compared with liposome-encapsulated Hb and Hb-loaded SiO(2) particles, such core-shell nanovehicles show substantially enhanced release performance of Hb in vitro. This finding opens up a new window of liposome-based formulations as drug delivery nanovehicles for widespread pharmaceutical applications.

Pseudomonas sp. as a Source of Medium Chain Length Polyhydroxyalkanoates for Controlled Drug Delivery: Perspective

Controlled drug delivery technology represents one of the most rapidly advancing areas of science. They offer numerous advantages compared to conventional dosage forms including improved efficacy, reduced toxicity, improved patient compliance and convenience. Over the past several decades, many delivery tools or methods were developed such as viral vector, liposome-based delivery system, polymer-based delivery system, and intelligent delivery system. Recently, nonviral vectors, especially those based on biodegradable polymers, have been widely investigated as vectors. Unlike the other polymers tested, polyhydroxyalkanoates (PHAs) have been intensively investigated as a family of biodegradable and biocompatible materials for in vivo applications as implantable tissue engineering material as well as release vectors for various drugs. On the other hand, the direct use of these polyesters has been hampered by their hydrophobic character and some physical shortcomings, while its random copolymers fulfilled the expectation of biomedical researchers by exhibiting significant mechanical and thermal properties. This paper reviews the strategies adapted to make functional polymer to be utilized as delivery system.

Biomolecular Structure and Modeling: Historical Perspective

physics, chemistry, and biology have been connected by a web of causal explanation organized by induction-based theories that telescope into one another. … Thus, quantum theory underlies atomic physics, which is the foundation of reagent chemistry and its specialized offshoot biochemistry, which interlock with molecular biology — essentially, the chemistry of organic macromolecules — and hence, through successively higher levels of organization, cellular, organismic, and evolutionary biology. … Such is the unifying and highly productive understanding of the world that has evolved in the natural sciences.

Injectable microsphere/hydrogel combination systems for localized protein delivery

Injectable delivery systems for therapeutic proteins (e.g., hydrogels and microspheres) have attracted wide attention. Hydrogels, however, may release their hydrophilic contents too rapidly in a large initial burst, and phagocytes may clear microspheres within a relatively short time period after administration. We hypothesized that microsphere/hydrogel combination systems could achieve a controlled and sustained release of proteins as an injectable delivery system. To test this hypothesis, we prepared PLGA microspheres containing a model protein and mixed these with alginate gels. The mixing ratio of the components was the primary controlling parameter of the protein release. This approach could be useful for development of injectable and localized drug delivery systems.

Dissolution test optimization for meloxicam in the tablet pharmaceutical form

Meloxicam is a broadly used drug in the therapeutics for the osteoarthritis and rheumatoid arthritis treatments in adults, and it is available in the Brazilian market, as tablet and capsule pharmaceutical forms. The present work aimed to establish conditions for accomplishment of the dissolution test of 15 mg meloxicam tablets (A and B test products), compared with the reference product, since there is no monograph about dissolution assays for meloxicam in official summaries. To optimize the conditions several parameters were tested and, according to obtained results, the use of pH 7.5 phosphate buffer (900mL, at 37 ± 0.5ºC) as dissolution medium, paddle method (apparatus 2), stirring speed of the dissolution medium at 100 rpm and collect time of 60 minutes were considered satisfactory. The samples were quantified by UV spectrophotometric method at 362 nm. The products presented kinetics of first-order. Dissolution efficiency values were of 83.25, 83.73 and 88.10% for the A, B and reference products, respectively. Factors f1 and f2 were calculated and similarity of the tested medicines was demonstrated. The dissolution test was validated presenting selectivity, linearity, precision and accuracy within of the acceptance criteria.

Drug Delivery Devices Based on Mesoporous Silicate

A mesoporous material based on aluminosilicate mixture was studied to investigate its ability to include drugs and then release them. Nonsteroidal anti-inflammatory agents such as diflunisal, naproxen, ibuprofen and its sodium salt have been used in this study. The preparation of the mesoporous material and its characterization by X-ray, N2 absorption-desorption isotherm, and thermogravimetry analysis have been described. Drug loading was performed by a soaking procedure. Drug-loaded matrices were characterized for entrapped drug amount, water absorption ability, and thermogravimetric behavior. Drug release studies also were performed at pH 1.1 and 6.8 mimicking gastrointestinal fluids. Experimental results showed that this type of matrix is able to trap the bioactive agents by a soaking procedure and, then, to release them in conditions mimicking the biological fluids. Also, the high affinity of these matrices for water makes them potentially biocompatible. Release data suggest that the matrix impregnated with diflunisal offers good potential as a system for the modified drug release.

Chemotherapeutic implants via subcritical CO2 modification

Polymer-based biomaterials have a broad range of current applications in medicine. Many implants generate a favorable biomedical outcome solely by providing short-term mechanical stability that allows healing of the surrounding tissues. An example is polymeric reconstructive resorbable plates having initial strengths sufficient to stabilize bone segments while allowing the osteosynthesis needed to restore original function following tumor resection. Simultaneous, localized delivery of the widely employed chemotherapeutic paclitaxel following tumor removal presents a particularly desirable goal in this context. By using compressed/subcritical CO(2) at moderate pressures (as opposed to the more familiar supercritical pressures) to embed paclitaxel in clinically utilized reconstructive plating, the form of the implant can be preserved while adding an inherently localized chemotherapeutic function. In vitro tests demonstrate the efficacy of the embedded paclitaxel against adherent MCF-7 breast cancer cells within the immediate area of the polylactic acid (PLA). CO(2) can be utilized to add dual structural-chemotherapeutic function to polymeric surfaces without a change in form. The ability to 'piggyback' chemotherapeutic function into nearly any polymeric surface should find widespread utility.

Simultaneous determination of hydrazinocurcumin and phenol red in samples from rat intestinal permeability studies: HPLC method development and validation

Hydrazinocurcumin (HZC) is a patented multiactivity compound and is a potent derivative of curcumin which is not yet explored for further development as formulation and requires the determination of biopharmaceutical suitability of the molecule. Intestinal permeability and logP of a compound are two vital biopharmaceutical properties by which, any "hit" molecule proceeds towards NCE (new chemical entity) and govern formulation design of bioactive molecules. In this report, a simple, precise and accurate isocratic reverse phase (RP) liquid chromatography method for simultaneous analysis of HZC and phenol red, for the application in rat in situ single-pass intestinal perfusion (SPIP) was developed and validated using FDA bioanalytical guidelines. RP-HPLC method was developed on C-18 column with UV detection at 332 nm for both the compounds. Isocratic run with the mobile phase consisting of organic phase (methanol:acetonitrile:: 50:20 v/v) and water in the ratio of 80:20 v/v provided a short run time of 7 min with resolution of more then two without interference of blank matrix. The working/expected concentration range for HZC and phenol red were 0.5-50 and 2-200 microg/ml. LOQs for HZC and phenol red of the method was found to be 0.167 and 0.271 microg/ml respectively. The validation parameters indicate that method was suitable for the intended purpose. Permeability, considering water flux with the help of non-permeable marker phenol red was calculated to be 0.34 x 10(-4)cm/s. Along with other descriptors, logP (1.78) and MW (<500) of HZC makes it a potential candidate for oral formulation.

Functional role of P-glycoprotein in limiting peroral drug absorption: optimizing drug delivery

P-glycoprotein (P-gp) associated multi-drug resistance is one of the major challenges in the chemotherapy of various cancers. On the other hand, it is now widely recognized that P-gp influences drug transport across various biological membranes. To this end, there is an increasing trend to optimize pharmacokinetics and drug delivery right from the initial stages of drug discovery by exploring all the possible mechanisms involved in 'deliverability'. Recent advances in molecular biology techniques and biochemical characterization methodologies have helped in identification of various transporters involved in absorption or secretion of drugs. P-gp, an efflux pump expressed along the gastrointestinal tract, limits the permeability of many drugs and thus affects their peroral absorption and bioavailability. A fundamental insight and thorough understanding of P-gp and its functional role in limiting drug absorption is critical to improve predictability of dynamic absorption models and aid in selection of new candidates for development, and also widen the scope of peroral delivery for 'challenging' molecules.

Permeability studies in chitosan membranes. Effects of crosslinking and poly(ethylene oxide) addition

Pure chitosan, glutaraldehyde crosslinked chitosan, and a blend of chitosan with poly(ethylene oxide) (PEO) membranes were prepared. The three membranes were characterized in terms of their swelling capacities as well as their permeabilities to a drug model (sulfamerazine sodium salt). For the permeation experiments, the variables analyzed were the type of membrane and the initial drug concentration in the liquid phase (from 0.1% to 1.5%). Permeability coefficients were calculated using UV spectroscopy. The results showed that for the three analyzed membranes, the permeability did not change with time (over the studied time interval). An increase in the permeability for CHI/PEO membranes compared to those made of pure chitosan was also observed, possibly due to microporous region formation and/or crystallinity reduction. For the crosslinked membrane, an even higher increase in the permeability coefficient was observed. In this case, the increase was attributed to free volume variation.

Analytical method for monitoring concentrations of cyclosporin and lovastatin in vitro in an everted rat intestinal sac absorption model

Cyclosporin A (CSA) and lovastatin (LV) are lipophilic drugs, which show poor and erratic absorption when administered perorally. The permeability of these compounds can be increased transiently by altering the membrane characteristics of the absorptive epithelium by the use of sorption promoters (SPs). In the present work a simple validated HPLC method utilizing an isocratic mobile phase with short retention times for CSA and LV was developed in order to monitor their concentrations in Kreb's Ringer bicarbonate (KRB) solution in vitro in intestinal sac absorption model. The same method was utilized to determine the apparent permeability coefficients and absorption profiles of CSA and LV by a modified Wilson-Wiseman method. Drugs were analysed by a reversed-phase HPLC method using a Shim-pack C18 column. An isocratic mobile phase containing acetonitrile and water in the proportions 70:30 and 80:20 was used for the HPLC analysis of CSA and LV, respectively. The flow-rate was 2 ml/min and quantitative determinations were carried out at 215 nm at 70 degrees C for CSA. In the case of LV the flow-rate was 1 ml/min and detection was done at 238 nm at 25 degrees C. The method was found to be specific as none of the proposed SPs, components of KRB or intestinal sac artefacts interfered with the drug peaks. Recovery studies and intra- and inter-day variations were within statistical limits. The limits of detection were 250 and 10 ng/ml and the limits of quantitation were 400 and 30 ng/ml for CSA and LV, respectively. The calibration curve was found to be linear in concentration range of 0.5-6 microg/ml for CSA and 0.05-0.4 microg/ml for LV. The proposed method was found to be rapid and selective and hence can be applied for continuous monitoring of CSA and LV in vitro in intestinal sac absorption studies.

Insulin therapies - past, present and future

The discovery of insulin is one of the greatest milestones in medical history. This discovery revolutionized the use of peptides and proteins as therapeutic agents. For more than six decades, insulin from different animal sources was used, until the breakthrough in biotechnology made it possible to produce human insulin in sufficient amounts. The evolution of the biotechnological era gave rise to modified insulins to solve some of the bottlenecks in insulin therapy. Efforts are currently focused towards developing non-invasive insulin delivery systems, and there are several competing technologies in different stages of development. The next few years will see several novel approaches to mimic the endogenous release and kinetics of insulin, and also many improved analogues designed to achieve better control and effective treatment of diabetes.