The role of biopharmaceutics in the development of a clinical nanoparticle formulation of MK-0869: a Beagle dog model predicts improved bioavailability and diminished food effect on absorption in human

Drug nanocrystals: A way toward scale-up

Drug nanocrystals comprise unique drug delivery platforms playing a significantly important and distinctive role in drug delivery and as such, the industry and academia are spending a lot of their time and money in developing the nanocrystal products. The current research works in this field depict a vivid shift from lab scale optimization studies to scale up focused studies. In this emerging scenario of nanocrystal technology, a review on some exemplary and progressing research studies with either scalability as their objective or upscaling as their future scope may smoothen the future upscaling attempts in this field. Hence, this paper reviews the efforts of such research works as case studies since an analysis of such research studies may input certain beneficial knowledge to carry out more scale up based research works on nanocrystals.

Application of physiologically based absorption modeling to formulation development of a low solubility, low permeability weak base: mechanistic investigation of food effect

Physiologically based pharmacokinetic (PBPK) modeling has been broadly used to facilitate drug development, hereby we developed a PBPK model to systematically investigate the underlying mechanisms of the observed positive food effect of compound X (cpd X) and to strategically explore the feasible approaches to mitigate the food effect. Cpd X is a weak base with pH-dependent solubility; the compound displays significant and dose-dependent food effect in humans, leading to a nonadherence of drug administration. A GastroPlus Opt logD Model was selected for pharmacokinetic simulation under both fasted and fed conditions, where the biopharmaceutic parameters (e.g., solubility and permeability) for cpd X were determined in vitro, and human pharmacokinetic disposition properties were predicted from preclinical data and then optimized with clinical pharmacokinetic data. A parameter sensitivity analysis was performed to evaluate the effect of particle size on the cpd X absorption. A PBPK model was successfully developed for cpd X; its pharmacokinetic parameters (e.g., C max, AUCinf, and t max) predicted at different oral doses were within ±25% of the observed mean values. The in vivo solubility (in duodenum) and mean precipitation time under fed conditions were estimated to be 7.4- and 3.4-fold higher than those under fasted conditions, respectively. The PBPK modeling analysis provided a reasonable explanation for the underlying mechanism for the observed positive food effect of the cpd X in humans. Oral absorption of the cpd X can be increased by reducing the particle size (<100 nm) of an active pharmaceutical ingredient under fasted conditions and therefore, reduce the cpd X food effect correspondingly.

From bench to humans: formulation development of a poorly water soluble drug to mitigate food effect

This study presents a formulation approach that was shown to mitigate the dramatic food effect observed for a BCS Class II drug. In vitro (dissolution), in vivo (dog), and in silico (GastroPlus®) models were developed to understand the food effect and design strategies to mitigate it. The results showed that such models can be used successfully to mimic the clinically observed food effect. GastroPlus® modeling showed that food effect was primarily due to the extensive solubilization of the drug into the dietary lipid content of the meal. Several formulations were screened for dissolution rate using the biorelevant dissolution tests. Surfactant type and binder amount were found to play a significant role in the dissolution rate of the tablet prototypes that were manufactured using a high-shear wet granulation process. The performance of the lead prototypes (exhibiting best in vitro dissolution performance) was tested in dogs and human subjects. A new formulation approach, where vitamin E TPGS was included in the tablet formulation, was found to mitigate the food effect in humans.

Engineered nanocrystal technology: in-vivo fate, targeting and applications in drug delivery

Formulation of nanocrystals is a robust approach which can improve delivery of poorly water soluble drugs, a challenge pharmaceutical industry has been facing since long. Large scale production of nanocrystals is done by techniques like precipitation, media milling and, high pressure homogenization. Application of appropriate stabilizers along with drying accords long term stability and commercial viability to nanocrystals. These can be administered through oral, parenteral, pulmonary, dermal and ocular routes showing their high therapeutic applicability. They serve to target drug molecules in specific regions through size manipulation and surface modification. This review dwells upon the in-vivo fate and varying applications in addition to the facets of drug nanocrystals stated above.

A study on enhanced intestinal permeability of clarithromycin nanoparticles

The main objective of the present study was to determine the permeability of clarithromycin (CLA)-PLGA nanoparticles using single-pass intestinal perfusion technique in rats. Clarithromycin nanoparticles were prepared by nano-precipitation according to the modified quasi emulsion solvent diffusion technique and evaluated for their physicochemical characteristics. Permeability coefficients (Peff) in anaesthetized rats were determined at 3 different concentrations. Drug solution or suspensions in PBS was perfused through a cannulated jejunal segment and samples were taken from outlet tubing at different time points up to 90 min. Microbiological assay of CLA and phenol red in the samples were analyzed using an agar well diffusion procedure and HPLC method respectively. The average particle size of prepared nanoparticles was 305 ± 134 nm. The mean Peff of CLA solution in concentrations of 150, 250 and 400 µg/mL was found to be 1.20 (±0.32) ×10-3, 9.62 (±0.46) ×10-4, and 1.36 (±0.95) ×10-3 cm/sec, respectively. The corresponding values for the same concentration of nanoparticles were found to be 2.74 (±0.73) ×10-3, 2.45 (±0.88) ×10-3, and 3.68 (±0.46) ×10-3 cm/s, respectively. The two-tailed Student’s t-test showed that the intestinal permeability of CLA nanoparticle suspensions in prepared concentrations were significantly increased in comparison with its solution.

Preparation and pharmacokinetic study of aprepitant-sulfobutyl ether-β-cyclodextrin complex

Aprepitant (APR), a neurokinin 1 receptor antagonist, is an approved treatment for chemotherapy-induced nausea and vomiting and for post-operative nausea and vomiting. However, it has poor water solubility. This study was performed to optimize the capsule formulation of an inclusion complex of APR with sulfobutyl ether-β-cyclodextrin (SBE-β-CD), and to evaluate its water solubility, dissolution rate, and bioavailability. The complex was prepared through the saturated-aqueous solution method and then characterized by Fourier transform infrared spectroscopy, x-ray powder diffraction, and differential scanning calorimetry. Subsequently, a pharmacokinetic study was performed using liquid chromatography-tandem mass spectrometry. Emend, which features an innovative formulation that incorporates drug nanoparticles with high bioavailability, was used as a reference for comparison with the optimized formulation. As a result, the dissolution rates and extent of release of the test formulation in various media were enhanced relative to those of Emend. The bioavailability of the drug complex was comparable to that of Emend. In summary, the SBE-β-CD complexation could provide a practical and cost-effective option for enhancing the solubility and bioavailability of APR according to our research.

Novel continuous flow technology for the development of a nanostructured aprepitant formulation with improved pharmacokinetic properties

The oral bioavailability of Aprepitant is limited by poor dissolution of the compound in the gastrointestinal tract which is more prominent in the fasted state resulting in significant positive food effect. Due to the low aqueous solubility of the active substance the product development has been focused on decreasing the particle size of the active compound down to the submicron range in order to overcome this disadvantageous pharmacokinetic property. The marketed drug consisting of wet-milled nanocrystals exhibits significantly higher oral bioavailability in the fasted state and reduced food effect when compared to the unformulated compound. We have developed a novel process for the production of a nanostructured Aprepitant formulation in which the generation of the nanosized particles takes place at molecular level. The process relies on controlled continuous flow precipitation of the compound from its solution in the presence of stabilizers. The precise control of the production parameters (mixing geometry, flow rates, temperature, etc.) allows to tailor the physicochemical properties and biological performance of the active compound. We have prepared a novel nanostructured Aprepitant formulation using this method and compared its physicochemical and pharmacokinetic properties with the reference compound and the marketed nanoformula. We found that our method produces a stable amorphous solid form comprising novel nanostructured particles having a particle size of less than 100 nm with instantaneous redispersibility characteristics and improved apparent solubility and permeability. In vivo beagle dog pharmacokinetic studies showed that the novel formula exhibited greatly improved pharmacokinetic characteristics when compared to the reference compound, while serum blood concentrations for the nanostructured formula and the wet-milled formula were similar. The marked food effect observed for the reference compound was practically eliminated by our formulation method. These results indicate that the novel continuous flow precipitation technology is a suitable tool to prepare nanostructured formulations with similar, or even superior in vitro and in vivo characteristics when compared to the industrial standard milling technology.

Surface-stabilized lopinavir nanoparticles enhance oral bioavailability without coadministration of ritonavir

Aim: The aim of the present study was to prepare surface-stabilized nanoparticles (NPs) for oral bioavailability enhancement of lopinavir (LPN), a Biopharmaceutics Classification System class II antiretroviral drug that possesses low oral bioavailability due to its poor aqueous solubility and extensive metabolism by liver microsomal enzymes. Materials & methods: Surfactant-stabilized LPN-NPs were prepared by combination of antisolvent precipitation and high-pressure homogenization techniques using polyvinyl alcohol as a suitable stabilizer. LPN-NPs were freeze dried by a universal stepwise freeze-drying cycle using mannitol as the cryoprotectant. Pharmacokinetics after oral administration of LPN-NPs were evaluated in male Sprague–Dawley rats and were compared with free LPN coadministered with ritonavir (conventional formulation). Results & conclusion: Freeze-dried stabilized LPN-NPs possessed particle sizes of approximately 320 nm and a narrow particle size distribution (polydispersity index <0.2). The surface-stabilized LPN-NPs (without ritonavir) demonstrated a 3.11-fold enhancement in bioavailability in comparison to free LPN with ritonavir (conventional formulation).

Original submitted 26 March 2012; Revised submitted 14 September 2012; Published online 25 January 2013

Recent advancements in mechanical reduction methods: particulate systems

The screening of new active pharmaceutical ingredients (APIs) has become more streamlined and as a result the number of new drugs in the pipeline is steadily increasing. However, a major limiting factor of new API approval and market introduction is the low solubility associated with a large percentage of these new drugs. While many modification strategies have been studied to improve solubility such as salt formation and addition of cosolvents, most provide only marginal success and have severe disadvantages. One of the most successful methods to date is the mechanical reduction of drug particle size, inherently increasing the surface area of the particles and, as described by the Noyes-Whitney equation, the dissolution rate. Drug micronization has been the gold standard to achieve these improvements; however, the extremely low solubility of some new chemical entities is not significantly affected by size reduction in this range. A reduction in size to the nanometric scale is necessary. Bottom-up and top-down techniques are utilized to produce drug crystals in this size range; however, as discussed in this review, top-down approaches have provided greater enhancements in drug usability on the industrial scale. The six FDA approved products that all exploit top-down approaches confirm this. In this review, the advantages and disadvantages of both approaches will be discussed in addition to specific top-down techniques and the improvements they contribute to the pharmaceutical field.

Amorphous solid dispersions and nano-crystal technologies for poorly water-soluble drug delivery

Poor water-solubility is a common characteristic of drug candidates in pharmaceutical development pipelines today. Various processes have been developed to increase the solubility, dissolution rate and bioavailability of these active ingredients belonging to BCS II and IV classifications. Over the last decade, nano-crystal delivery forms and amorphous solid dispersions have become well established in commercially available products and industry literature. This article is a comparative analysis of these two methodologies primarily for orally delivered medicaments. The thermodynamic and kinetic theories relative to these technologies are presented along with marketed product evaluations and a survey of commercial relevant scientific literature.

Strategies to address low drug solubility in discovery and development

Drugs with low water solubility are predisposed to low and variable oral bioavailability and, therefore, to variability in clinical response. Despite significant efforts to "design in" acceptable developability properties (including aqueous solubility) during lead optimization, approximately 40% of currently marketed compounds and most current drug development candidates remain poorly water-soluble. The fact that so many drug candidates of this type are advanced into development and clinical assessment is testament to an increasingly sophisticated understanding of the approaches that can be taken to promote apparent solubility in the gastrointestinal tract and to support drug exposure after oral administration. Here we provide a detailed commentary on the major challenges to the progression of a poorly water-soluble lead or development candidate and review the approaches and strategies that can be taken to facilitate compound progression. In particular, we address the fundamental principles that underpin the use of strategies, including pH adjustment and salt-form selection, polymorphs, cocrystals, cosolvents, surfactants, cyclodextrins, particle size reduction, amorphous solid dispersions, and lipid-based formulations. In each case, the theoretical basis for utility is described along with a detailed review of recent advances in the field. The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology (e.g., solid dispersions, lipid-based formulations, or salt forms) where required.

Application of drug nanocrystal technologies on oral drug delivery of poorly soluble drugs

The limited solubility and dissolution rate exhibited by poorly soluble drugs is major challenges in the pharmaceutical process. Following oral administration, the poorly soluble drugs generally show a low and erratic bioavailability which may lead to therapeutic failure. Pure drug nanocrystals, generated by "bottom up" or "top down" technologies, facilitate a significant improvement on dissolution behavior of poorly soluble drugs due to their enormous surface area, which in turn lead to substantial improvement in oral absorption. This is the most distinguished achievement of drug nanocrystals among their performances in various administration routes, reflected by the fact that most of the marketed products based on the nanocrystals technology are for oral application. After detailed investigations on various technologies associated with production of drug nanocrystals and their in vitro physicochemical properties, during the last decade more attentions have been paid into their in vivo behaviors. This review mainly describes the in vivo performances of oral drug nanocrystals exhibited in animals related to the pharmacokinetic, efficacy and safety characteristics. The technologies and evaluation associated with the solidification process of the drug nanocrystals suspensions were also discussed in detail.

Drug nanocrystals in the commercial pharmaceutical development process

Nanosizing is one of the most important drug delivery platform approaches for the commercial development of poorly soluble drug molecules. The research efforts of many industrial and academic groups have resulted in various particle size reduction techniques. From an industrial point of view, the two most advanced top-down processes used at the commercial scale are wet ball milling and high pressure homogenization. Initial issues such as abrasion, long milling times and other downstream-processing challenges have been solved. With the better understanding of the biopharmaceutical aspects of poorly water-soluble drugs, the in vivo success rate for drug nanocrystals has become more apparent. The clinical effectiveness of nanocrystals is proven by the fact that there are currently six FDA approved nanocrystal products on the market. Alternative approaches such as bottom-up processes or combination technologies have also gained considerable interest. Due to the versatility of nanosizing technology at the milligram scale up to production scale, nanosuspensions are currently used at all stages of commercial drug development, Today, all major pharmaceutical companies have realized the potential of drug nanocrystals and included this universal formulation approach into their decision trees.

Novel ultra-cryo milling and co-grinding technique in liquid nitrogen to produce dissolution-enhanced nanoparticles for poorly water-soluble drugs

A novel ultra-cryo milling micronization technique for pharmaceutical powders using liquid nitrogen (LN2 milling) was used to grind phenytoin, a poorly water-soluble drug, to improve its dissolution rate. LN2 milling produced particles that were much finer and more uniform in size and shape than particles produced by jet milling. However, the dissolution rate of LN2-milled phenytoin was the same as that of unground phenytoin due to agglomeration of the submicron particles. To overcome this, phenytoin was co-ground with polyvinylpyrrolidone (PVP). The dissolution rate of co-ground phenytoin was much higher than that of original phenytoin, single-ground phenytoin, a physical mixture of phenytoin and PVP, or jet-milled phenytoin. X-Ray diffraction showed that the crystalline state of mixtures co-ground by LN2 milling remained unchanged. The equivalent improvement in dissolution, whether phenytoin was co-ground or separately ground and then mixed with PVP, suggested that even when co-ground, the grinding of PVP and phenytoin occurs essentially independently. Mixing original PVP with ground phenytoin provided a slight improvement in dissolution, indicating that the particle size of PVP is important for improving dissolution. When mixed with ground phenytoin, PVP ground by LN2 milling aided the wettability and dispersion of phenytoin, enhancing utilization of the large surface area of ground phenytoin. Co-grinding phenytoin with other excipients such as Eudragit L100, hypromellose, hypromellose acetate-succinate, microcrystalline cellulose, hydroxypropylcellulose and carboxymethyl cellulose also improved the dissolution profile, indicating an ultra-cryo milling and co-grinding technique in liquid nitrogen has a broad applicability of the dissolution enhancement of phenytoin.

Challenges and opportunities in the delivery of cancer therapeutics

The idea that cancer is not one but many diseases has completely changed the oncology landscape and promoted the development of personalized cancer therapy. Based on a better understanding of the mechanisms of cancer cell proliferation and tumor growth, novel therapies have emerged to address unmet medical needs and effectively treat pre-identified, responsive patients. These novel therapies require specific drug-delivery strategies that depend on the type and location of cancer, as well as the type of drugs administered, that is, a small molecule, a peptide, a therapeutic protein or a monoclonal antibody. Systemic cancer drugs are administered through three major routes that show different challenges with regard to delivery: these are oral administration, intravenous infusion and subcutaneous injection. This review presents and discusses the challenges and opportunities of the drug-delivery systems for each of these administration routes. It will be shown that, for the good of the patients, every time a drug-delivery system is used to administer anticancer drugs, the patients get a major benefit from that specific system: either improved efficacy, a better tolerability and toxicity profile, or even a combination of both effects.

Polymeric particulate technologies for oral drug delivery and targeting: a pathophysiological perspective

The oral route for delivery of pharmaceuticals is the most widely used and accepted. Nanoparticles and microparticles are increasingly being applied within this arena to optimize drug targeting and bioavailability. Frequently the carrier systems used are either constructed from or contain polymeric materials. Examples of these nanocarriers include polymeric nanoparticles, solid lipid nanocarriers, self-nanoemulsifying drug delivery systems and nanocrystals. It is the purpose of this review to describe these cutting edge technologies and specifically focus on the interaction and fate of these polymers within the gastrointestinal system.

Crystalline nanosuspensions as potential toxicology and clinical oral formulations for BCS II/IV compounds

Nanosuspensions, formulations based on the reduction of the active pharmaceutical ingredient (API) particle size in the sub-micron range and most typically around 100-200 nm, represent a valuable option for formulators to facilitate oral absorption of Biopharmaceutics Classification System class II and IV compounds. Their ability to increase the API dissolution rate and subsequent absorption and thus oral bioavailability has been demonstrated in preclinical and clinical settings. This review summarizes the current experience in the biopharmaceutic field with the use of nanosuspensions as oral delivery formulations. The principles behind nanosuspensions as well as the in vitro and in silico evaluation are discussed, while examples are presented highlighting both successes as well as limitations in their application as either toxicology or clinical formulations.

Challenges and opportunities in achieving bioequivalence for fixed-dose combination products

Fixed-dose combination (FDC) products are becoming a popular treatment option because of increased patient compliance and convenience, improved clinical effectiveness, and reduced cost to the patient, among several other reasons. A commonly applied approach for approval of a FDC product is demonstrating bioequivalence between the FDC and co-administration of individual mono-products, provided that there is adequate safety and efficacy data for co-administration of the individual agents. However, achieving bioequivalence between the FDC and individual mono-products can be very challenging, and sometimes not possible since combining multiple active ingredients, especially insoluble molecules, in a single drug product could complicate its biopharmaceutical and pharmacokinetic behavior. In this review, some of the major challenges often encountered while assessing bioequivalence during FDC development will be presented along with discussion of future opportunities to facilitate FDC development and approval.

Modification of physicochemical characteristics of active pharmaceutical ingredients and application of supersaturatable dosage forms for improving bioavailability of poorly absorbed drugs

New chemical entities are required to possess physicochemical characteristics that result in acceptable oral absorption. However, many promising candidates need physicochemical modification or application of special formulation technology. This review discusses strategies for overcoming physicochemical problems during the development at the preformulation and formulation stages with emphasis on overcoming the most typical problem, low solubility. Solubility of active pharmaceutical ingredients can be improved by employing metastable states, salt forms, or cocrystals. Since the usefulness of salt forms is well recognized, it is the normal strategy to select the most suitable salt form through extensive screening in the current developmental study. Promising formulation technologies used to overcome the low solubility problem include liquid-filled capsules, self-emulsifying formulations, solid dispersions, and nanosuspensions. Current knowledge for each formulation is discussed from both theoretical and practical viewpoints, and their advantages and disadvantages are presented.

HP55-coated capsule containing PLGA/RS nanoparticles for oral delivery of insulin

In this work, we designed and developed a two-stage delivery system composed of enteric capsule and cationic nanoparticles for oral delivery of insulin. The enteric capsule was coated with pH-sensitive hydroxypropyl methylcellulose phthalate (HP55), which could selectively release insulin from nanoparticles in the intestinal tract, instead of stomach. The biodegradable poly(lactic-co-glycolic acid) (PLGA) was selected as the matrix for loading insulin. Eurdragit(®) RS (RS) was also introduced to the nanoparticles for enhancing the penetration of insulin across the mucosal surface in the intestine. The nanoparticles were prepared with the multiple emulsions solvent evaporation method via ultrasonic emulsification. The optimized nanoparticles have a mean size of 285nm, a positive zeta potential of 42mV. The encapsulation efficiency was up to 73.9%. In vitro results revealed that the initial burst release of insulin from nanoparticles was markedly reduced at pH 1.2, which mimics the stomach environment. In vivo effects of the capsule containing insulin PLGA/RS nanoparticles were also investigated in diabetic rat models. The oral delivered capsules induced a prolonged reduction in blood glucose levels. The pharmacological availability was found to be approximately 9.2%. All the results indicated that the integration of HP55-coated capsule with cationic nanoparticles may be a promising platform for oral delivery of insulin with high bioavailability.

The effect of food on the oral bioavailability of drugs: a review of current developments and pharmaceutical technologies for pharmacokinetic control

Here we review the mediation of the food effects on drugs by pharmaceutical technologies. The pharmacokinetics of drugs are affected by the interaction of drugs with food, which changes drug physicochemical and physiological properties (food effects). Several pharmaceutical technologies may be used to control food effects. Drugs exhibit different patterns of solubilization depending on release formulations. Formulations such as nanoparticle, solid dispersion and cyclodextrin systems, may control the solubility and release of insoluble drugs. Other controlled-release technologies, such as osmotic-controlled release or colon-specific delivery systems may also control food effects. As the structure of drug candidates becomes more complex, different methods of investigation, such as in vitro and in vivo correlation and in silico simulation will be required to predict drug characteristics and food effects.

Nanoparticulate systems as drug carriers: the need

Development of nanoparticles for drug delivery has progressed by leaps and bounds over the last few decades, facilitating the possibility of an efficacious therapy for some fatal diseases. This development has stemmed from either the unsuitable physicochemical characteristics of the existing drug molecules, such as limited solubility and hence poor bioavailability, or the inadequacy of the conventional delivery systems to provide safe and efficient delivery. This chapter focuses on the precise need for the development of these novel nanoparticulate drug carriers and reasons for their popularity with the drug delivery scientists. The text also discusses the various strategies, including different formulation and targeting approaches, which have been adopted to overcome the challenges presented by the inherent properties of the drug molecules. Examples of nanoparticulate drug delivery systems which have already gained market approval have been cited in the discussion, wherever applicable.

Drug delivery strategies for poorly water-soluble drugs: the industrial perspective

INTRODUCTION

For poorly soluble compounds, a good bioavailability is typically needed to assess the therapeutic index and the suitability of the compound for technical development. In industry, the selection of the delivery technology is not only driven by technical targets, but also by constraints, such as production costs, time required for development and the intellectual property situation.

AREAS COVERED

This review covers current developments in parenteral and oral delivery technologies and products for poorly water-soluble compounds, such as nano-suspensions, solid dispersions and liposomes. In addition, the use of biorelevant dissolution media to assess dissolution and solubility properties is described. Suggestions are also included to systematically address development hurdles typical of poorly water-soluble compounds intended for parenteral or oral administration.

EXPERT OPINION

A holistic assessment is recommended to select the appropriate delivery technology by taking into account technical as well as intellectual property considerations. Therefore, first and foremost, a comprehensive physico-chemical characterization of poorly water-soluble compounds can provide the key for a successful selection and development outcome. In this context, the identified physical form of the compound in the formulation is used as a guide for a risk-benefit assessment of the selected oral delivery technology. The potential of nano-suspensions for intravenous administration is unclear. In the case of oral administration, nano-suspensions are mainly used to improve the oral absorption characteristics of micronized formulations. The development of an in situ instantaneous solubilization method, based on stable, standardized liposomes with low toxicity, opens new avenues to solubilize poorly water-soluble compounds.

Polymeric nanoparticles for increased oral bioavailability and rapid absorption using celecoxib as a model of a low-solubility, high-permeability drug

Purpose

To demonstrate drug/polymer nanoparticles can increase the rate and extent of oral absorption of a low-solubility, high-permeability drug.

Methods

Amorphous drug/polymer nanoparticles containing celecoxib were prepared using ethyl cellulose and either sodium caseinate or bile salt. Nanoparticles were characterized using dynamic light scattering, transmission and scanning electron microscopy, and differential scanning calorimetry. Drug release and resuspension studies were performed using high-performance liquid chromatography. Pharmacokinetic studies were performed in dogs and humans.

Results

A physical model is presented describing the nanoparticle state of matter and release performance. Nanoparticles dosed orally in aqueous suspensions provided higher systemic exposure and faster attainment of peak plasma concentrations than commercial capsules, with median time to maximum drug concentration (Tmax) of 0.75 h in humans for nanoparticles vs. 3 h for commercial capsules. Nanoparticles released celecoxib rapidly and provided higher dissolved-drug concentrations than micronized crystalline drug. Nanoparticle suspensions are stable for several days and can be spray-dried to form dry powders that resuspend in water.

Conclusions

Drug/polymer nanoparticles are well suited for providing rapid oral absorption and increased bioavailability of BCS Class II drugs.

Nanosizing for oral and parenteral drug delivery: a perspective on formulating poorly-water soluble compounds using wet media milling technology

A significant percentage of active pharmaceutical ingredients identified through discovery screening programs is poorly soluble in water. These molecules are often difficult to formulate using conventional approaches and are associated with innumerable formulation-related performance issues, e.g. poor bioavailability, lack of dose proportionality, slow onset of action and other attributes leading to poor patient compliance. In addition, for parenteral products, these molecules are generally administered with co-solvents and thus have many undesirable side effects. Wet media milling is one of the leading particle size reduction approaches that have been successfully used to formulate these problematic compounds. The approach is a water-based media milling process where micron-sized drug particles are shear-fractured into nanometer-sized particles. Nanoparticle dispersions are stable and typically have a mean diameter of less than 200 nm with 90% of the particles being less than 400 nm. The formulation consists only of water, drug and one or more GRAS excipients. Drug concentrations approaching 300-400mg/g can be targeted with the use of minimal amounts stabilizer. Typically, on average, the drug to stabilizer ratio on a weight basis ranges from 2:1 to 20:1. These liquid nanodispersions exhibit acceptable shelf-life and can be post-processed into various types of solid dosage forms. Nanoparticulate-based drug products have been shown to improve bioavailability and enhance drug exposure for oral and parenteral dosage forms. Suitable formulations for the most commonly used routes of administration can be identified with milligram quantities of drug substance providing the discovery scientist an alternate avenue for screening and identifying superior leads. In the last few years, formulating poorly water soluble compounds as nanosuspensions has evolved from a conception to a realization. The versatility and applicability of this drug delivery platform are just beginning to be realized.

Pharmaceutical nanocrystals by nanomilling: critical process parameters, particle fracturing and stabilization methods

OBJECTIVES

Wet milling is a common technique to produce drug nanocrystals. Stability of the nanocrystals is a critical question, and different kinds of stabilizers, e.g. polymers, celluloses, surfactants and lipids, have been tested for various drugs. Still, the question about how to select the best stabilizer to a certain drug material and also to a selected process is open.

KEY FINDINGS

Many different factors, such as surface energy, hydrophobicity, solubility, viscosity and functional groups, affect the stability of the formed nanosuspensions. Affinity of the stabilizer to the particle surfaces seems to be the most important parameter. This affinity is partly related to the surface energy and hydrophobicity of the surfaces and stabilizers.

SUMMARY

In this review the most important factors affecting nanocrystal formulation and efficacy of stabilizers are presented. In order to widen understanding of the milling process, the most important variables related to milling techniques and particle fracturing processes during the milling are briefly presented.

Coaxial electrospray formulations for improving oral absorption of a poorly water-soluble drug

Development of oral dosage forms containing poorly water-soluble drugs is a major challenge in the pharmaceutical industry. This paper describes the use of coaxial electrospray deposition as a promising formulation technology for oral delivery of poorly water-soluble drugs. The technology produced core-shell particles composed of griseofulvin and poly(methacrylic acid-co-methyl methacrylate) (Eudragit L-100), with a diameter of around 1 μm. The drug phase was in an amorphous state when the griseofulvin core was coated with the Eudragit L-100 shell. The in vitro dissolution and in vivo oral absorption studies revealed that the core-shell formulation significantly improved dissolution and absorption behaviors, presumably because of a reduction in particle size, improvement in dispersity, and amorphization. Results demonstrated that coaxial electrospray deposition possesses great potential as novel formulation technology for enhancing oral absorption of poorly water-soluble drugs.

Safety evaluation of aprepitant for the prevention of chemotherapy-induced nausea and vomiting

INTRODUCTION

Aprepitant is the only neurokinin (NK(1)) receptor antagonist (RA) approved for prevention of chemotherapy-induced nausea and vomiting (CINV). Aprepitant is co-administered with a 5-HT(3) RA and a corticosteroid. Although aprepitant is safe, in most clinical settings potential drug-drug interactions need to be considered before prescription.

AREAS COVERED

This article thoroughly reviews aprepitant and, in particular, clinically relevant safety aspects of the drug. The literature review was performed using Medline with the following search terms: adverse events, aprepitant, chemotherapy, CYP3A4, MK-0869, neurokinin(1) receptor antagonist, safety and tolerability.

EXPERT OPINION

The recommended antiemetic regimen of aprepitant, a 5-HT(3) RA and a corticosteroid is safe. The combination of aprepitant, a 5-HT(3) RA and dexamethasone is now the gold standard of antiemetic treatment in prevention of CINV induced by HEC, or by the combination of an anthracycline and cyclophosphamide. The intravenous formulation of aprepitant used as a single dose is expected to be of benefit to cancer patients.

Early development evaluation of AZD8081: a substrate for the NK receptors

The purpose of the present study was to find out if AZD8081, a dual neurokinin (NK)1/2 receptor antagonist, was suitable for development of an oral, solid immediate release (IR) formulation and in a further perspective also as an oral extended release (ER) formulation. AZD8081 is a base with pK(a) values <2.5 and about 8.5. The measured intrinsic solubility is about 0.1 mg/mL and the solubility in FaSSIF (fasted simulated small intestinal fluid) is about 3.2 mg/mL. Aqueous buffer solutions are stable for at least 1 month between pH 1-7 up to 37°C. In the solid-state, a mixture of amorphous and crystalline substance showed significant chemical instability in the initial stress testing studies. No degradation was, however, observed for highly crystalline material at similar conditions. It is concluded that the impurity profile and/or the present solid-state of the batches affect the stability of the substance. The amorphous contribution of the substance is the main cause to the observed degradation in solid-state. Crystalline AZD8081 is polymorphic with two known monotropic forms, form A and form B. Both forms are only slightly hygroscopic ansolvates with melting points of approximately 108°C and 117°C, respectively. Form B is the more stable of the two forms and is therefore most suited for further development. The candidate is suitable for development of standard IR formulations since no specific limitations of significance for formulation development were identified. In addition, the good stability in human intestinal fluid and in colon slurry makes AZD8081 a suitable candidate for ER formulation.