Calix[n]arenes are macrocyclic cone-shaped compounds formed from phenolic units linked by methylene groups in the ortho position. Structural features make calix[n]arenes a versatile class of molecules that are of great interest, particularly in the pharmaceutical field. The cavity-like shape gives calix[n]arenes the ability to selectively encapsulate ions or neutral molecules, which can be used to generate carrier systems capable of increasing the solubility and diffusivity of chemical species. These resulting systems can function as deliverers of bioactive guest molecules. Host-guest molecular interactions act as the cornerstone that prompts the application of calix[n]arenes in the pharmaceutical field. Understanding their interactions in host-guest complexes is essential for the development and application of new therapeutics. In the present review, the most utilized analytical techniques for characterizing calix[n]arene inclusion complexes are discussed, and an overview of the ability of a variety of calix[n]arenes to work as host molecules for the development of chemical entities of pharmaceutical interest is also presented.

A rapid increase in the emergence and spread of microbes resistant to conventionally used antibiotics has become a major threat to global health care. Antimicrobial peptides (AMPs) are being considered as a potential source of novel antibiotics because of their numerous advantages such as broad-spectrum activity, lower tendency to induce resistance, immunomodulatory response and unique mode of action. However, AMPs has several drawbacks such as; susceptibility to protease degradation, toxicity and high costs of manufacture. So, extensive research efforts are underway to explore the therapeutic potential of these fascinating natural compounds. This review highlights the potential of small cationic antimicrobial peptidomimetics (SCAMPs; Mw ≍ 700) as new generation antibiotics. In particular, we focused on recently identified small active pharmacophore from bulky templates of native AMPs β-peptides, and lipopeptides. In addition, various design strategy recently undertaken to improve the physicochemical properties (proteolytic stability & plasma protein binding) of small cationic peptides have been discussed.

Identification of factors affecting platelet reactivity (PR) and high PR (HPR) or high platelet inhibition (HPI) rates while on prasugrel maintenance dose (MD) might be helpful in avoiding ischemic or bleeding complications.We retrospectively analyzed all patients (n=233) treated in our institution between April 2010 and November 2012 who had platelet function assessment pre-prasugrel and following prasugrel 10 mg MD for at least 5 days, using the VerifyNow P2Y12 platelet function assay. Multiple linear regression and logistic regression models were applied to identify independent factors affecting post-prasugrel PR level, HPR and HPI status.The amount of variance in PR under prasugrel MD that could be explained by the model was 25.9% (adjusted R2), p<0.001. Pre-prasugrel treatment PR, acute coronary syndrome (ACS), prasugrel loading and smoking uniquely accounted for 10.8%, 1.3%, 3.5% and 1.2% of the observed variance, respectively. HPR and HPI were observed in 7.7% and 13.7% of the cases, respectively. On multivariate analysis, pre-prasugrel PR in the upper quartile (>313 PRU) was the only independent factor associated with HPR under prasugrel MD. In contrast, pre-prasugrel PR in the lower quartile (<242 PRU) and prasugrel loading emerged as the only independent predictors of HPI. In patients under different clinical settings receiving prasugrel 10 mg MD a significant amount of the PR variability in response to prasugrel may be explained by pre- treatment PR level, ACS, prasugrel loading and smoking status. A high pre- treatment PR is associated with HPR, while a low pre-treatment PR and prasugrel loading predict HPI.

Supercritical fluid particle design (SCF PD) offers a number of routes to improve solubility and dissolution rate for enhancing the bioavailability of poorly water-soluble drugs, which can be adopted through an in-depth knowledge of SCF PD processes and the molecular properties of active pharmaceutical ingredients (API) and drug delivery system (DDS). Combining with research experiences in our laboratory, this review focuses on the most recent development of different routes (nano-micron particles, polymorphic particles, composite particles and bio-drug particles) to improve solubility and dissolution rate of poorly water-soluble drugs, covering the fundamental concept of SCF and the principle of SCF PD processes which are typically used to control particle size, shape, morphology and particle form and hence enable notable improvement in the dissolution rate of the poorly water-soluble drugs. The progress of the industrialization of SCF PD processes in pharmaceutical manufacturing environment with scaled-up plant under current good manufacturing process (GMP) specification is also considered in this review.

A surprisingly large proportion of new chemical entities (NCE) are emerging from the drug discovery pipeline, and many active components extracted from herbal medicines are water insoluble, which represents a great challenge for their development. Nanosuspensions, which are submicron colloidal dispersions of pure drug particles that are stabilised by a small percentage of the excipients, could dramatically enhance the saturated solubility, dissolution rate and adhesion of drug particles to cell membranes. Nanosuspensions are the most suitable for drugs that require high dosing or have limited administrative volume. After 20 years of development, several oral products and one injectable product are commercially available. The aim of this review is to fill the gap between rational formulation designs and the in vivo performance of poorly water-soluble drug nanosuspensions. Specifically, this review will correlate characteristics of nanosuspension formulations, including drug property, particle size, crystallinity, stabiliser and surface property, with their transport, pharmacokinetics, bioactivity and toxicity after delivery by different administration routes. The elucidation of the mechanisms of targeted drug delivery, cellular transport and internalisation of nanosuspensions are also reviewed to interpret the in vivo performance of these nanosuspensions. Moreover, the recent application of nanosuspensions for poorly water-soluble herbal medicines is highlighted.

Hot melt extrusion (HME) is a powerful technology to enhance the solubility and bioavailability of poorly water-soluble drugs by producing amorphous solid dispersions. Although the number of articles and patents about HME increased dramatically in the past twenty years, there are very few commercial products by far. The three main obstacles limiting the commercial application of HME are summarized as thermal degradation of heat-sensitive drugs at high process temperature, recrystallization of amorphous drugs during storage and dissolving process, and difficulty to obtain products with reproducible physicochemical properties. Many efforts have been taken in recent years to understand the basic mechanism underlying these obstacles and then to overcome them. This article reviewed and summarized the limitations, recent advances, and future prospects of HME.

In recent years, nanosuspensions have been accepted as a valuable drug delivery system for poorly water-soluble drugs. Top-down and bottom-up technologies are the two main approaches for generating nanosuspensions. Several products manufactured by the top-down technologies have been commercialized successfully demonstrating that the processing features of the technologies are adaptable to industrial scale operation and meeting high pharmaceutical quality control standards. Nanosuspensions of poorly soluble drugs have shown to achieve dramatic improvements on the in vivo performance of the drugs including the enhancement of bioavailability and elimination of food effect when administered orally. This review will focus on the preparation of nanosuspensions by the top-down technologies. The influence of drug physicochemical properties on the nanosuspension forming process and the subsequent conversion into a dry powder form will be discussed with proposed mechanisms. In addition, the criteria for selection of stabilizers will be reviewed. The characteristics of drugs and stabilizers as well as their interaction effects on the redispersion properties of a dry powder prepared from a nanosuspension will be highlighted. The different administration routes of nanosuspensions are also presented with their potential therapeutic benefits.

Many newly discovered drug molecules have low aqueous solubility, which results in low bioavailability. One way to improve their dissolution is to formulate them as nanoparticles, which have high specific surface areas, consequently increasing the dissolution rate and solubility. Nanoparticles can be produced via top-down or bottom-up methods. Top-down techniques such as wet milling and high pressure homogenisation involve reducing large particles to nano-sizes. Some pharmaceutical products made by these processes have been marketed. Bottom-up methods such as precipitation and controlled droplet evaporation form nanoparticles from molecules in solution. To minimise aggregation upon drying and promote redispersion of the nanoparticles upon reconstitution or administration, hydrophilic matrix formers are added to the formulation. However, the nanoparticles will eventually agglomerate together after dispersing in the liquid and hinders dissolution. Currently there is no pharmacopoeial method specified for nanoparticles. Amongst the current dissolution apparatus available for powders, the flow-through cell has been shown to be the most suitable. Regulatory and pharmacopoeial standards should be established in the future to standardise the dissolution testing of nanoparticles. More nanoparticle formulations of new hydrophobic drugs are expected to be developed in the future with the advancement of nanotechnology. However, the agglomeration problem is inherent and difficult to overcome. Thus the benefit of dissolution enhancement often cannot be fully realised. On the other hand, chemical strategies such as modifying the parent drug molecule to form a more soluble salt form, prodrug, or cyclodextrin complexation are well established and have been shown to be effective in enhancing dissolution. Thus the value of nanoformulations needs to be interpreted in the light of their limitations. Chemical approaches should also be considered in new product development.

Solid dispersions have been widely studied as an attractive formulation strategy for the increasingly prevalent poorly water-soluble drug compounds, including herbal medicines, often leading to improvements in drug dissolution rate and bioavailability. However, several challenges are encountered with solid dispersions, for instance regarding their physical stability, and the full potential of these formulations has yet to be reached. Solid dispersions have mainly been used to produce immediate release systems using water-soluble polymers but an extended release system may provide equal or better performance due to enhancement in the pharmacokinetics and low variability in plasma concentration. Progress in processing technologies and particle engineering provides new opportunities to prepare particle-based solid dispersions with control of physical characteristics and tailored drug release kinetics. Spray-drying and electrospraying are both technologies that allow production and continuous manufacturing of particle-based amorphous solid dispersions in a single step process and electrospinning further allows the production of fiber based systems. This review presents the use of spray drying and electrospraying/electrospinning as techniques for preparing particle-based solid dispersions, describes the particle formation processes via numerical and experimental models and discusses particle engineering using these techniques. Examples are given on the applications of these techniques for preparing solid dispersions and the challenges associated with the techniques such as stability, preparation of final dosage form and scale-up are also discussed.