State of the art of nanocrystals – Special features, production, nanotoxicology aspects and intracellular delivery

Hybrid drug nanocrystals

Nanocrystals show promise to deliver poorly water-soluble drugs to yield systemic exposure. However, our knowledge regarding the in vivo fate of nanocrystals is in its infancy, as nanocrystallization is simply viewed as an approach to enhance the dissolution of drug crystals. The dying crystal phenomenon inspired the development of hybrid nanocrystals by physically embedding fluorophores into the crystal lattice. This approach achieved concurrent therapy and bioimaging and is well-established to study pharmacokinetics and nanocrystal dissolution in vivo. Nanocrystals also offer the advantage of long-term durability in the body for interacting with biological tissues and cells. This review introduces the hybrid nanocrystal technique, including the theoretical concepts, preparation, and applications. We also discuss the latest development in self-discriminative hybrid nanocrystals utilizing environment-responsive probes. This review will stimulate further development and application of nanocrystal-based drug delivery systems for theranostic strategies.

Engineering of solidified glyburide nanocrystals for tablet formulation via loading of carriers: downstream processing, characterization, and bioavailability

INTRODUCTION

Presenting poorly water-soluble drugs as nanoparticles has shown to be an effective technique in enhancing drug dissolution rate, intrinsic solubility, and thus oral bioavailability. Nevertheless, working with nanoparticles introduces many challenges, one of which is their physical instability. Formulating nanoparticles into a solid dosage form may overcome such challenges and thus unlock the potential benefits of nanosizing.

METHODS

The current work investigates the possibility of developing a novel solid dosage form, with enhanced dissolution rate, whereby nanocrystals (~400 nm) of the class II Biopharmaceutical Classification System drug, glyburide (GBD) were fabricated through combined precipitation and homogenization procedures. Using a novel, but scalable, spraying technique, GBD nanocrystals were loaded onto commonly used tablet fillers, water-soluble lactose monohydrate (LAC), and water insoluble microcrystalline cellulose (MCC). Conventional tableting processes were then used to convert the powders generated into a tablet dosage form.

RESULTS

Studies of redispersibility showed considerable preservation of size characteristics of GBD nanocrystals during downstream processing with redispersibility indices of 105 and 118 for GBD-LAC and GBD-MCC, respectively. Characterization by differential scanning calorimetry, powder X-ray diffraction, and scanning electron microscopy showed that the powders generated powders contained nanosized crystals of GBD which adhered to carrier surfaces. Powder flowability was characterized using Hausner ratio (HR) and Carr's index (CI). GBD-LAC-loaded particles exhibited poor flowability with CI and HR of 37.5% and 1.60, respectively, whilst GBD-MCC particles showed a slightly improved flowability with CI and HR of 26.47% and 1.36, respectively. The novel tablet dosage form met US Pharmacopeia specifications, including drug content, hardness, and friability.

CONCLUSION

Higher dissolution rates were observed from the nanocrystal-based tablets compared to the microsized and commercial drug formulations. Moreover, the novel nanocrystal tablet dosage forms showed enhanced in vivo performance with area under the plasma concentration- time curve in the first 24 hours values 1.97 and 2.24 times greater than that of marketed tablets.

Drug nanocrystals: Fabrication methods and promising therapeutic applications

The drug nanocrystals (NCs) with unique physicochemical properties are now considered as a promising drug delivery system for poorly water-soluble drugs. So far >20 formulations of NCs have been approved in the market. In this review, we summarized recent advances of NCs with emphasis on their therapeutic applications based on administration route and disease states. At the end, we present a brief description of the future perspectives of NCs and their potential role as a promising drug delivery system. As a strategy for solubilization and bioavailability enhancement, the NCs have gained significant success. Besides this, the function of NCs is still far from developed. The emerging NC-based drug delivery approach would widen the applications of NCs in drug delivery and bio-medical field. Their in vitro and in vivo fate is extremely unclear; and the development of hybrid NCs with environment-sensitive fluorophores may assist to extend the scope of bio-imaging and provide better insight to their intracellular uptake kinetics, in vitro and in vivo.

Enhanced dissolution/caco-2 permeability, pharmacokinetic and pharmacodynamic performance of re-dispersible eprosartan mesylate nanopowder

Eprosartan mesylate is an angiotensin receptor blocker which suffers from extremely poor bioavailability owing to its poor solubility and poor permeability. The rationale of the present work was to design the drug delivery system capable of overcoming these constraints. Nanoformulation of eprosartan mesylate was developed using ultrasonic wave-assisted liquid-antisolvent technique. Nanoformulation was further freeze dried with the addition of 1% of mannitol resulting in formation of re-dispersible EPM nanopowder. To prove our proof of principle, the re-dispersed nanopowder with z-average particle size 165.2 ± 1.8 nm was evaluated enormously for in-vitro dissolution behaviour and permeability assay through Caco-2 cell model. In-vitro dissolution study was performed at pH 1.2, pH 4.5 and pH 6.8. Result demonstrates enhanced dissolution from EPM nanopowder with negligible pH dependence. Transport studies accomplished using validated Caco-2 based cell model showed 11-fold enhanced apparent permeability of redispersed nanopowder when compared to pure EPM and corresponding physical mixture (p < 0.0001). In-vivo study reveals, exceptionally strong variations in plasma concentration of EPM through nanopowder (62 mg/kg) formulation when compared with physical mixture and pure EPM (62 mg/kg) group. Moreover, study manifests that 5-fold lower dose (12.4 mg/kg) of developed formulation yields higher exposure (4600 ± 36 ng·mL^-1·h) than pure EPM (2349 ± 34 ng·mL^-1·h) and corresponding physical mixture (2456 ± 49 ng·mL^-1·h) at therapeutic dose (62 mg/kg). Further, L-NAME induced hypertensive model was undertaken to investigate effect of reduced dose of EPM nanopowder on systolic blood pressure, biochemical analysis and histopathology of heart. Results revealed pronounced antihypertensive potential of re-dispersed EPM nanopowder at 5-fold lower dose (12.4 mg/kg). In conclusion, our study indicates that nanopowder delivery might be the promising approach for providing enhanced oral bioavailability at lower dose.

Evaluation of improved oral bioavailability of ritonavir nanosuspension

The main objective of this study was to evaluate the pharmacokinetics of ritonavir (RTV) nanosuspension in rats in both fed and fasted state in comparison with coarse powder, physical mixture and commercial product (Norvir®). The point to point relation model was generated between the results of in vitro dissolution and in vivo pharmacokinetic studies. The oral RTV nanosuspension was prepared with microfluidization method. Nanosuspension was obtained with 540-550 nm of particle size, 0.1-0.4 of particle size distribution and about -20 mV of zeta potential values. According to in vivo pharmacokinetic studies in rats, C_max and AUC_0-t values in nanosuspension displayed an 8.9- and 12.5-fold increase compared to the coarse powder, and a 1.9- and 2.1-fold increase compared to the commercial product, respectively in the fed group. The point to point relation model showed that the correlation model was significant. It is concluded that nanosuspension is a promising drug delivery system to enhance oral bioavailability of ritonavir.

Optimization and characterization of lambda-cyhalothrin solid nanodispersion by self-dispersing method

BACKGROUND

Pesticide is an important agricultural necessity to control plant diseases and pests, ensuring safe production of food. However, the low efficacy, large dosage and high-frequency use of conventional pesticide formulation seriously induced food safety and ecological environment issues. In this research, lambda-cyhalothrin solid nanodispersion (LCSND) was developed by a self-dispersing method.

RESULTS

The mean particle size of the lambda-cyhalothrin solid nanodispersion was 32.7 ± 1.1 nm. It exhibited excellent dispersibility, wettability and stability, especially the improved bioavailability compared to the commercial formulations. Notably, the solid nanodisperison had a small particle size and large specific surface area. The solid nanodispersion without organic solvents can minimize the environment pollution and overcome the instability characteristic of the liquid formulations.

CONCLUSION

Therefore, lambda-cyhalothrin solid nanodispersion has broad application prospects in agricultural production and environmental protection. © 2018 Society of Chemical Industry.

In-situ dissolution and permeation studies of nanocrystal formulations with second-derivative UV spectroscopy

One of the most difficult challenges in developing nanocrystal formulations is to determine the dissolution behavior of nanocrystal suspensions (nanosuspensions), which occurs within seconds. Mefenamic acid (MFA) is a poorly soluble drug thought to limit the dissolution rate for membrane permeation. In this study, in-situ dissolution-permeation studies of a nanosuspension of mefenamic acid (MFA) were carried out using second-derivative UV spectroscopy. This method enabled us to distinguish between the concentrations of dissolved MFA and nano-suspended MFA via in-situ measurement and showed an improved dissolution rate of the nanosuspension compared to that of the microsuspension. The dissolution-permeation study with second-derivative UV spectroscopy revealed that the improved dissolution rate due to nanosized MFA resulted in an increase in the permeated amount of MFA. In addition, the solubility of MFA determined by HPLC after filtration with a 0.02-μm filter indicated that enhanced solubility due to nanosizing also improves the permeability of MFA. Therefore, we concluded that the solubility and dissolution rate enhancements attained by nanosizing would be key factors in increasing membrane transportation of MFA. These novel in-situ dissolution-permeation studies using second-derivative UV spectroscopy offer considerable promise for developing and characterizing nanocrystal formulations.

Albendazole nanocrystals with improved pharmacokinetic performance in mice

AIM

Albendazole (ABZ) is a broad-spectrum antiparasitic agent with poor aqueous solubility, which leads to poor/erratic bioavailability and therapeutic failures. Here, we aimed to produce a novel formulation of ABZ nanocrystals (ABZNC) and assess its pharmacokinetic performance in mice. Results/methodology: ABZNC were prepared by high-pressure homogenization and spray-drying processes. Redispersion capacity and solid yield were measured in order to obtain an optimized product. The final particle size was 415.69±7.40 nm and the solid yield was 72.32%. The pharmacokinetic parameters obtained in a mice model for ABZNC were enhanced (p < 0.05) with respect to the control formulation.

CONCLUSION

ABZNC with improved pharmacokinetic behavior were produced by a simple, inexpensive and potentially scalable methodology.

A critical review on grape polyphenols for neuroprotection: Strategies to enhance bioefficacy

The aging of populations worldwide is driving greater demands for dietary polyphenols which have been recognized as promising prophylactic and/or therapeutic agents in the context of neurodegeneration, and are ubiquitously present in plant-based diets. In particular, grape-derived products encompass a wide array of phenolic compounds purported with multiple health benefits including neuroprotective efficacy. Despite the increasing preclinical and clinical evidence demonstrating high potential of grape polyphenol (GPP)-rich botanicals in preventing and attenuating diverse neurodegenerative disorders, the limited bioavailability of GPPs, especially in the brain, generates questions as to their applications and effectiveness in neuroprotection. To address this issue, significant research efforts have been made to enhance oral bioavailability of GPPs via application of novel strategies. This review highlights some critical issues related to the bioavailability and neuroprotective efficacy of GPPs and GPP-rich botanicals. The representative bioavailability-enhancing strategies are critically reviewed to provide practical solutions for augmenting the bioefficacy of GPP-rich botanicals. Synergistic applications of encapsulation techniques (for physiochemical protection and bypassing xenobiotic metabolism) and dietary intervention strategies involving modulation of gut microbiota (for generating more bioavailable phenolic metabolites) appear promising, and may substantially enhance the bioefficacy, especially the neuroprotective efficacy, of orally consumed GPPs.

Enhanced Delivery of Imatinib into Vaginal Mucosa via a New Positively Charged Nanocrystal-Loaded in Situ Hydrogel Formulation for Treatment of Cervical Cancer

The present study was carried out to investigate the potential of cationic functionalization on imatinib nanocrystals to improve the mucoadhesiveness and, thus, delivery to the lesion of cervicovaginal tumors. Amino-group-functionalized imatinib nanocrystals (NC@PDA-NH₂) were prepared with near-spheroid shape, nanoscale size distribution, positive zeta potential, and relatively high drug content with the aid of the polydopamine-coating technique. Efficient interaction between NC@PDA-NH₂ and mucin was proven by mucin adsorption which was related to the positive zeta-potential value of NC@PDA-NH₂ and the change in the size distribution on mixing of NC@PDA-NH₂ and mucin. Cellular uptake, growth inhibition, and apoptosis induction in cervicovaginal cancer-related cells demonstrated the superiority of NC@PDA-NH₂ over unmodified nanocrystals. For practical intravaginal administration, NC@PDA-NH₂ was dispersed in Pluronic F127-based thermosensitive in situ hydrogel, which showed suitable gelation temperature and sustained-release profiles. In comparison with unmodified nanocrystals, NC@PDA-NH₂ exhibited extended residence on ex vivo murine vaginal mucosa, prolonged in vivo intravaginal residence, and enhanced inhibition on the growth of murine orthotopic cervicovaginal model tumors indicated by smaller tumor size, longer median survival time, and more intratumor apoptosis with negligible mucosal toxicity. In conclusion, cationic functionalization endowed NC@PDA-NH₂ significant mucoadhesiveness and, thus, good potential against cervicovaginal cancer via intravaginal administration.

Nanocrystalization: An Emerging Technology to Enhance the Bioavailability of Poorly Soluble Drugs

Most of the active pharmaceutical ingredient used in the management of disease have poor water solubility and offer grueling problems in drug formulation development since low solubility is generally associated with poor dissolution characteristics which leads to poor oral bioavailability. The great challenge for the development of a pharmaceutical product is to create its new formulation and drug delivery system to limit solubility problems of existing drug candidate. Limited drug-loading capacity requires a large amount of carrier material to get appropriate encapsulation of the drug, which is another major challenge in the development of pharmaceutical product which could be resolved by developing nanocrystals (NCs). A significant research in the past few years has been done to develop NCs which helps in the delivery of poorly water soluble drugs via different routes. The technology could continue to thrive as a useful tool in pharmaceutical sciences for the improvement of drug solubility, absorption and bioavailability. Many crystalline compounds have pulled in incredible consideration much of the time, due to their ability to show good physical and chemical properties when contrasted with their amorphous counterparts. Nanocrystals have been proven to show atypical properties compared to the bulk. This review article explores the principles of the important nanocrystallization techniques including NCs characterization and its application.

First-time oral administration of resveratrol-loaded layer-by-layer nanoparticles to rats – a pharmacokinetics study

trans-Resveratrol (RSV) is a plant-derived polyphenol endowed with a broad spectrum of promising therapeutic activities.

Development of carrier-free nanocrystals of poorly water-soluble drugs by exploring metastable zone of nucleation

There has been increasing interest in research and development of nanocrystals for the delivery of poorly water-soluble drugs that can be directly produced from solution. Compared with traditional carrier-based or encapsulation designs, drug nanocrystals circumvent possible side-effects due to carrier polymers and poor stability issues associated with encapsulation. The production of carrier-free nanocrystals requires careful control of nucleation and thus a thorough understanding of the relevant solution's metastable zone. A solution may stay supersaturated without forming any nuclei and become metastable. The maximal degree of supersaturation is known as the metastable zone width. When nucleation is triggered directly from the metastable zone, it helps to produce homogeneous nuclei leading to uniform nanocrystals. Herein, we report a study in which the solubility and metastable limit of paclitaxel (PTX) in ethanol aqueous solution were measured at 40 °C. A wide range of metastable compositions were studied to prepare carrier-free PTX nanocrystals with particle size smaller than 250 nm and PDI less than 0.25. Compared with the raw material, dissolution rate of PTX nanocrystals was significantly increased. The study enables production of high-quality drug nanocrystals for treating patients.

Highly Water-Soluble Orotic Acid Nanocrystals Produced by High-Energy Milling

Orotic acid (OA), a heterocyclic compound also known as vitamin B13, has shown potent antimalarial and cardiac protection activities; however, its limited water solubility has posed a barrier to its use in therapeutic approaches. Aiming to overcome this drawback, OA freeze-dried nanocrystal formulations (FA, FB, and FC) were developed by using the high-energy milling method. Polysorbate 80 (FA) and povacoat^® (FC) were used alone and combined (FB) as stabilizers. Nanocrystals were fully characterized by dynamic light scattering, laser diffraction, transmission electron microscopy, thermal analysis (thermogravimetry and derivative thermogravimetry, and differential scanning calorimetry), and X-ray powder diffraction revealing an acceptable polydispersity index, changes in the crystalline state with hydrate formation and z-average of 100-200 nm, a remarkable 200-time reduction compared to the OA raw material (44.3 μm). Furthermore, saturation solubility study showed an improvement of 13 times higher than the micronized powder. In addition, cytotoxicity assay revealed mild toxicity for the FB and FC formulations prepared with povacoat^®. OA nanocrystal platform can deliver innovative products allowing untapped the versatile potential of this drug substance candidate.

Safety, tolerability, and pharmacokinetics of long-acting injectable cabotegravir in low-risk HIV-uninfected individuals: HPTN 077, a phase 2a randomized controlled trial

BACKGROUND

Cabotegravir (CAB) is a novel strand-transfer integrase inhibitor being developed for HIV treatment and prevention. CAB is formulated both as an immediate-release oral tablet for daily administration and as a long-acting injectable suspension (long-acting CAB [CAB LA]) for intramuscular (IM) administration, which delivers prolonged plasma exposure to the drug after IM injection. HIV Prevention Trials Network study 077 (HPTN 077) evaluated the safety, tolerability, and pharmacokinetics of CAB LA in HIV-uninfected males and females at 8 sites in Brazil, Malawi, South Africa, and the United States.

METHODS AND FINDINGS

HPTN 077 was a double-blind, placebo-controlled phase 2a trial. Healthy individuals age 18-65 years at low HIV risk were randomized (3:1) to receive CAB or placebo (PBO). In the initial oral phase, participants received 1 daily oral tablet (CAB or PBO) for 4 weeks. Those without safety concerns in the oral phase continued and received injections in the injection phase (Cohort 1: 3 injections of CAB LA 800 mg or 0.9% saline as PBO IM every 12 weeks for 3 injection cycles; Cohort 2: CAB LA 600 mg or PBO IM for 5 injection cycles; the first 2 injections in Cohort 2 were separated by 4 weeks, the rest by 8 weeks). The primary analysis included weeks 5 to 41 of study participation, encompassing the injection phase. The cohorts were enrolled sequentially. Primary outcomes were safety and tolerability. Secondary outcomes included pharmacokinetics and events occurring during the oral and injection phases. Between February 9, 2015, and May 27, 2016, the study screened 443 individuals and enrolled 110 participants in Cohort 1 and 89 eligible participants in Cohort 2. Participant population characteristics were as follows: 66% female at birth; median age 31 years; 27% non-Hispanic white, 41% non-Hispanic black, 24% Hispanic/Latino, 3% Asian, and 6% mixed/other; and 6 transgender men and 1 transgender woman. Twenty-two (11%) participants discontinued the oral study product; 6 of these were for clinical or laboratory adverse events (AEs). Of those who received at least 1 CAB LA injection, 80% of Cohort 1 and 92% of Cohort 2 participants completed all injections; injection course completion rates were not different from those in the PBO arm. Injection site reactions (ISRs) were common (92% of Cohort 1 and 88% of Cohort 2 participants who received CAB LA reported any ISR). ISRs were mostly Grade 1 (mild) to Grade 2 (moderate), and 1 ISR event (Cohort 1) led to product discontinuation. Grade 2 or higher ISRs were the only AEs reported more commonly among CAB LA recipients than PBO recipients. Two Grade 3 (severe) ISRs occurred in CAB recipients, 1 in each cohort, but did not lead to product discontinuation in either case. Seven incident sexually transmitted infections were diagnosed in 6 participants. One HIV infection occurred in a participant 48 weeks after last injection of CAB LA: CAB was not detectable in plasma both at the time of first reactive HIV test and at the study visit 12 weeks prior to the first reactive test. Participants in Cohort 2 (unlike Cohort 1) consistently met prespecified pharmacokinetic targets of at least 95% of participants maintaining CAB trough concentrations above PA-IC90, and 80% maintaining trough concentrations above 4× PA-IC90. Study limitations include a modest sample size, a short course of injections, and a low-risk study population.

CONCLUSIONS

In this study, CAB LA was well tolerated at the doses and dosing intervals used. ISRs were common, but infrequently led to product discontinuation. CAB LA 600 mg every 8 weeks met pharmacokinetic targets for both male and female study participants. The safety and pharmacokinetic results observed support the further development of CAB LA, and efficacy studies of CAB LA for HIV treatment and prevention are in progress.

TRIAL REGISTRATION

ClinicalTrials.gov Registry: ClinicalTrials.gov Trial number: NCT02178800.

Smart nanocarrier based on PEGylated hyaluronic acid for deacetyl mycoepoxydience: High stability with enhanced bioavailability and efficiency

Deacetyl mycoepoxydience (DM) nanocrystals core were stabilized by the folate modified distearoylphosphatidyl ethanolamine-polyethylene glycol (DSPE-PEG₂₀₀₀-FA) as the active-targeting stabilizer and D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) as the reversion of multidrug resistance stabilizer, respectively. The DM nanocrystals was acted as the core and shelled by the polyethylene glycol-hyaluronic acid (PEG-HA). The optimal core-shell system demonstrated superior stability at 4 °C for 6 weeks by the stability study and higher dissolution velocity. Cytotoxicity in vitro and cell proliferation inhibition was evaluated by MCF-7 cells line. Furthermore, the core-shell nanocrystals revealed a concentration- and time-dependent cytotoxicity activity and enhanced the cell proliferation inhibition. Pharmacokinetic studies in rabbits showed core-shelled DM nanocrystals significantly increased AUC and t_1/2 and reduced CL_z compared to the DM solution for intravenous delivery. Results indicated that core-shell nanocrystals nanogel was successfully established with higher stability and the bioavailability of DM with higher safety was improved.

Permeability Behavior of Nanocrystalline Solid Dispersion of Dipyridamole Generated Using NanoCrySP Technology

Nanocrystals research has been an area of significant interest lately, providing oral bioavailability benefits to solubility- and/or dissolution rate-limited drugs. Drug nanocrystals are generated using top-down or bottom-up technologies. Combination technologies (Nanoedge, Nanopure XP and SmartCrystal) have been recently developed to generate nanocrystals of improved properties. Our lab has also contributed in this field by providing a ‘novel’ platform technology, NanoCrySP, for the generation of nanocrystals. NanoCrySP-generated nanocrystals have improved the oral bioavailability of various molecules. In this study, we aim to assess the permeability behavior of nanocrystals generated by NanoCrySP. Three samples of Dipyridamole (DPM) drug were used in this study: (1) DPM (micron-sized powder), (2) nanocrystals of DPM (NS), generated by media milling (as control) and, (3) nanocrystalline solid dispersion containing DPM (NSD) in the matrix of mannitol (MAN), generated using NanoCrySP technology. In vitro (Caco-2 cell lines) and ex vivo (everted gut sac) studies were conducted in this work. Cellular permeability (P_app) from apical-to-basolateral side in Caco-2 cell monolayer was found to be in the order NS > NSD > DPM, which was the same as their apparent solubility values. Higher P_app from a basolateral-to-apical side suggested a significant contribution of the P-gp efflux transport for DPM, while NS exhibited much higher inhibition of the efflux mechanism than NSD. Both NS and NSD showed higher permeation from the jejunum region in the ex vivo everted gut sac study. Interestingly, P_app of NSD was similar to NS in ex vivo everted gut sac model, however, NSD showed higher mucoadhesion than NS and DPM in this study.

Parenteral nanosuspensions: a brief review from solubility enhancement to more novel and specific applications

Advancements in in silico techniques of lead molecule selection have resulted in the failure of around 70% of new chemical entities (NCEs). Some of these molecules are getting rejected at final developmental stage resulting in wastage of money and resources. Unfavourable physicochemical properties affect ADME profile of any efficacious and potent molecule, which may ultimately lead to killing of NCE at final stage. Numerous techniques are being explored including nanocrystals for solubility enhancement purposes. Nanocrystals are the most successful and the ones which had a shorter gap between invention and subsequent commercialization of the first marketed product. Several nanocrystal-based products are commercially available and there is a paradigm shift in using approach from simply being solubility enhancement technique to more novel and specific applications. Some other aspects in relation to parenteral nanosuspensions are concentrations of surfactant to be used, scalability and in vivo fate. At present, there exists a wide gap due to poor understanding of these critical factors, which we have tried to address in this review. This review will focus on parenteral nanosuspensions, covering varied aspects especially stabilizers used, GRAS (Generally Recognized as Safe) status of stabilizers, scalability challenges, issues of physical and chemical stability, solidification techniques to combat stability problems and in vivo fate.

Fabrication and Characterization of Gliclazide Nanocrystals

Purpose: The main aim of the present investigation was to enhance the solubility of poorly soluble Gliclazide by nanocrystallization. Methods: In present investigation gliclazide nanocrystals were prepared by sonoprecipitation using Pluronic F68, Poly Vinyl Alcohol (PVA), Poly ethylene Glycol 6000 (PEG), Poly Vinyl Pyrrolidine (PVP K30) and Sodium Lauryl Sulphate (SLS) as stabilizers. Fourier Transform Infrared Spectroscopic study (FTIR), Differential Scanning Calorimetry (DSC) and X ray diffraction (XRD) studies were conducted to study the drug interactions. Size and zeta potential of the nanocrystals were evaluated. In vitro and in vivo studies of nanocrystals were conducted in comparison to pure gliclazide. Results: The Gliclazide nanocrystals (GN) showed mean particle size of 131±7.7 nm with a zeta potential of -26.6 mV. Stable nanocrystals were formed with 0.5% of PEG 6000. FTIR, DSC and XRD studies of nanocrystals showed absence of interactions and polymorphism. SEM photographs showed a change in morphology of crystals from rod to irregular shape. There is an increase in the saturation solubility and the percentage drug release from formulation GN5 (Optimized Gliclazide Nanocrystals) was found to be 98.5 in 15 min. In the in vivo study, GN5 nanocrystals have reduced the blood glucose level to 296.4±4.26 mg/dl in 12 hr. The nanocrystals showed lower tmax and higher Cmax values as compared to pure gliclazide. Conclusion: The prepared nanocrystals of gliclazide were stable without any drug polymer interactions. Increase in the dissolution of nanocrystals compared to pure gliclazide and significant reduction in blood glucose level in vivo indicated better bioavailability of the nanocrystals. Therefore, it is concluded that nanocrystal technology can be a promising tool to improve solubility and hence dissolution of a hydrophobic drug.

Residence time and uptake of porous and cationic maltodextrin-based nanoparticles in the nasal mucosa: Comparison with anionic and cationic nanoparticles

Different types of biodegradable nanoparticles (NP) have been studied as nasal mucosa cell delivery systems. These nanoparticles need to strongly interact with mucosa cells to deliver their payload. However, only a few simultaneous comparisons have been made and it is therefore difficult to determine the best candidate. Here we compared 5 types of nanoparticles with different surface charge (anionic or cationic) and various inner compositions as potential vectors: cationic and anionic liposomes, cationic and anionic PLGA (Poly Lactic co-Glycolic Acid) NP and porous and cationic maltodextrin NP (cationic surface with an anionic lipid core: NPL). We first quantified their nasal residence time after nasal administration in mice using in vivo live imaging and NPL showed the longest residence time. In vitro endocytosis on mucosal cells (airway epithelial cells, macrophages and dendritic cells) using labeled nanoparticles were performed by flow cytometry and confocal microscopy. Among the 5 nanoparticles, NPL were taken up to the greatest extent by the 3 different cell lines and the endocytosis mechanisms were characterized. Taken together, we observed that the nanoparticles' cationic surface charge is insufficient to improve mucosal residence time and cellular uptake and that the NPL are the best candidates to interact with airway mucosal cells.

Nanocrystals of Poorly Soluble Drugs: Drug Bioavailability and Physicochemical Stability

Many approaches have been developed over time to overcome the bioavailability limitations of poorly soluble drugs. With the advances in nanotechnology in recent decades, science and industry have been approaching this issue through the formulation of drugs as nanocrystals, which consist of “pure drugs and a minimum of surface active agents required for stabilization”. They are defined as “carrier-free submicron colloidal drug delivery systems with a mean particle size in the nanometer range, typically between 10–800 nm”. The primary importance of these nanoparticles was the reduction of particle size to nanoscale dimensions, with an increase in the particle surface area in contact with the dissolution medium, and thus in bioavailability. This approach has been proven successful, as demonstrated by the number of such drug products on the market. Nonetheless, despite the definition that indicates nanocrystals as a “carrier-free” system, surface active agents are necessary to prevent colloidal particles aggregation and thus improve stability. In addition, in more recent years, nanocrystal properties and technologies have attracted the interest of researchers as a means to obtain colloidal particles with modified biological properties, and thus their interest is now also addressed to modify the drug delivery and targeting. The present work provides an overview of the achievements in improving the bioavailability of poorly soluble drugs according to their administration route, describes the methods developed to overcome physicochemical and stability-related problems, and in particular reviews different stabilizers and surface agents that are able to modify the drug delivery and targeting.

Nanomedicine: Principles, Properties, and Regulatory Issues

Several scientific areas have benefited significantly from the introduction of nanotechnology and the respective evolution. This is especially noteworthy in the development of new drug substances and products. This review focuses on the introduction of nanomedicines in the pharmaceutical market, and all the controversy associated to basic concepts related to these nanosystems, and the numerous methodologies applied for enhanced knowledge. Due to the properties conferred by the nanoscale, the challenges for nanotechnology implementation, specifically in the pharmaceutical development of new drug products and respective regulatory issues are critically discussed, mainly focused on the European Union context. Finally, issues pertaining to the current applications and future developments are presented.

Comparative studies on amphotericin B nanosuspensions prepared by a high pressure homogenization method and an antisolvent precipitation method

Amphotericin B (AmB) is a widely used polyene antifungal agent; however, its poor solubility limits its clinical application. In this study, AmB nanosuspensions were prepared by a high pressure homogenization method (AmB-HPH) and an antisolvent precipitation method (AmB-AP) to improve the drug solubility. To reveal the distinct influences of these two different preparation methods, systematic comparisons of particle size, crystalline state, wettability, in vitro dissolution and in vivo pharmacokinetics on the properties of AmB-HPH and AmB-AP were performed. The results indicated that AmB-AP was in an amorphous state, exhibiting higher saturation solubility and dissolution rate than those of AmB-HPH in the crystalline state. However, the relative bioavailability of AmB-HPH was higher than that of AmB-AP in vivo, which was likely attributed to its better stability. In conclusion, both AmB-HPH and AmB-AP can enhance the solubility and bioavailability of AmB, but the stability of the nanosuspension prepared by the anti-solvent precipitation method should be carefully considered.

Pramipexole nanocrystals for transdermal permeation: Characterization and its enhancement micro-mechanism

The purpose of the study was to improve transdermal delivery of pramipexole via nanocrystals and investigate the enhancement micro-mechanism. Pramipexole nanocrystals were prepared using wet media milling method and incorporated into carbomer gel. In vitro permeation studies through rabbit ear skin indicated that the cumulative permeation amount of pramipexole from nanocrystals in 24 h was 2.75 times more than that from coarse suspension. Investigations of selective follicular closing technique indicated that approximately 33.88% of the total permeation from nanocrystals was contributed to the follicular pathway, which was confirmed by scanning electron microscopy images. In vitro permeation and in vivo pharmacokinetic studies indicated that pramipexole from nanocrystal gel showed a higher permeation profile than that from coarse suspension gel. Overall, nanocrystals could improve transdermal delivery of pramipexole through transepidermal and transfollicular pathways by the nanosized particles.

Design Space and QbD Approach for Production of Drug Nanocrystals by Wet Media Milling Techniques

Drug nanocrystals are nanosized solid drug particles, the most important application of which is the improvement of solubility properties of poorly soluble drug materials. Drug nanocrystals can be produced by many different techniques, but the mostly used are different kinds of media milling techniques; in milling, particle size of bulk sized drug material is decreased, with the aid of milling beads, to nanometer scale. Utilization of Quality by Design, QbD, approach in nanomilling improves the process-understanding of the system, and recently, the number of studies using the QbD approach in nanomilling has increased. In the QbD approach, the quality is built into the products and processes throughout the whole production chain. Definition of Critical Quality Attributes, CQAs, determines the targeted final product properties. CQAs are confirmed by setting Critical Process Parameters, CPPs, which include both process parameters but also input variables, like stabilizer amount or the solid state form of the drug. Finally, Design Space determines the limits in which CPPs should be in order to reach CQAs. This review discusses the milling process and process variables, CPPs, their impact on product properties, CQAs and challenges of the QbD approach in nanomilling studies.

Cryochemically Obtained Nanoforms of Antimicrobial Drug Substance Dioxidine and Their Physico-chemical and Structural Properties

Nanoforms of the antimicrobial drug substance 2,3-bis-(hydroxymethyl) quinoxaline-N,N′-dioxide with particles sizes between 50 and 300 nm were obtained by cryochemical modification of the initial pharmaceutical substance using a freeze-drying technique and were characterized by different physicochemical methods (FTIR, UV-Vis, 1H-NMR, DSC, TG and X-ray diffraction) and transmission electron microscopy (TEM). The data obtained from FTIR- and UV–Vis-spectroscopy confirmed the unaltered chemical structure of dioxidine molecules due to the cryochemical modification method. At the same time, X-ray diffraction and thermal analysis data show the change of the crystal structure compared to the parameters of the initial pharmaceutical dioxidine substance. A higher dissolution rate was revealed for cryomodified dioxidine nanoforms. The existence of three polymorphic crystal phases was established for cryomodified dioxidine samples possessed by some thermal activation processes: two anhydrous polymorphic phases, triclinic (T) and monoclinic (M), and one hydrated form (H).

A drug-delivering-drug strategy for combined treatment of metastatic breast cancer

Treatment of metastatic cancer continues to be a huge challenge worldwide. Notably, drug nanocrystals (Ns) in nanosuspensions clearly belong to a type of nanoparticle. Therefore, a question arose as to whether these drug particles can also be applied as carriers for drug delivery. Here, we design a novel paclitaxel (PTX) nanocrystal stabilized with complexes of matrix metalloproteinase (MMP)-sensitive β-casein/marimastat (MATT) for co-delivering MATT and PTX and combined therapy of metastatic breast cancer. The prepared Ns (200 nm) with a drug-loading of >50% were potent in treatment of metastatic cancer, which markedly inhibited MMP expression and activity and greatly blocked the lung metastasis and angiogenesis. In conclusion, employing protein-drug complexes as stabilizers, Ns with dual payloads are developed and are a promising strategy for co-delivery. Furthermore, the developed Ns can target the tumor microenvironment and cancer cells and, as a result, enable efficient treatment for breast metastatic cancer.

Design and characterization of loratadine nanosuspension prepared by ultrasonic-assisted precipitation

Nanoparticle engineering is a well-defined technique employed as a novel and effective method in drug design and delivery. It is widely used to control particle size, as well as the morphological and physicochemical properties of active pharmaceutical ingredients. Furthermore, it serves as a method of pre-dispersion preparation for various dosage form developments. Nanotechnology produces nanomaterials with enhanced properties in terms of solubility, dissolution and permeability. In this work, ultrasonic-assisted precipitation was employed to produce nanosuspensions of poorly water-soluble loratadine, using different stabilizers. The objective of our study was attempting to prepare solid nanoparticles of loratadine to be used as a possible intermediate for designing various dosage forms. The effects of the type(s) and concentration(s) of stabilizer(s) on mean particle size were assessed. Optimal process parameters required to produce homogeneous nanoparticles with particle size below 500 nm and polydispersity less than 0.3 were determined both for precipitation and ultrasonication. Pre-dispersions were evaluated for their particle size, polydispersity index and zeta potential. Freeze-drying was employed to produce dry nanoparticles. Particle size, particle size distribution and zeta potential of the dried nanoparticles were measured after reconstitution in water. Besides thermal analysis using DSC and structural analyses (XRPD and FT-IR), the morphological characteristics and dissolution behaviors were also investigated. The selected freeze-dried nanoparticles had a mean particle size range of 353-441 nm, a polydispersity index ranging between 0.167 and 0.229 and a zeta potential between -25.7 and -20.7 mV. These results suggest that material and process parameters were successfully optimized. DSC and XRPD spectra confirmed interactions between the formulation's components during freeze-drying. The solid nanoparticles showed 30-42% of cumulative release after 10 min compared to less than 1% of dissolution characterizing loratadine without pre-processing. This study demonstrates that preparing dried loratadine nanoparticles suitable for designing effective drug preparations is a feasible approach.

Promising nanotherapy in treating leishmaniasis

Leishmaniases are infectious diseases caused by an intracellular protozoan in humans by 20 different species of Leishmania among more than 53 species. There are at least twelve million cases of infections worldwide and three hundred and fifty million people are at risk in at least 98 developing countries in Africa, South-East Asia, and the Americas. Only Brazil presented high burden for both visceral leishmaniasis (VL) and cutaneous (CL). Chemotherapy is the main means of dealing with this infection. Nevertheless, only a few effective drugs are available, and each has a particular disadvantage; toxicity and long-term regimens compromise most chemotherapeutic options, which decreases patient compliance and adherence to the treatment and consequently the emergence of drug-resistant strains. Nano drug delivery systems (NanoDDS) can direct antileishmanial drug substances for intracellular localization in macrophage-rich organs such as bone marrow, liver, and spleen. This strategy can improve the therapeutic efficacy and reduce the toxic effects of several antileishmanial drug substances. This review is an effort to comprehensively compile recent findings, with the aim of advancing understanding of the importance of nanotechnology for treating leishmaniases.

Production of pure drug nanocrystals and nano co-crystals by confinement methods

The use of drug nanocrystals in the drug formulation is increasing due to the large number of poorly water-soluble drug compounds synthetized and due to the advantages brought by the nanonization process. The downsizing processes are done using a top-down approach (milling and homogenization currently employed at the industrial level), while the crystallization process is performed by bottom-up techniques (e.g., antisolvent precipitation, use of supercritical fluids or spray and freeze drying). In addition, the production of nanocrystals in confined environment can be achieved within microfluidics channels. This review analyzes the processes for the preparation of nanocrystals and co-crystals, divided by top-down and bottom-up approaches, together with their combinations. The combination of both strategies merges the favorable features of each process and avoids the disadvantages of single processes. Overall, the applicability of drug nanocrystals is highlighted by the widespread research on the production processes at the engineering, pharmaceutical, and nanotechnology level.

Tablets made from paper

The possibility to compress ordinary paper into tablets was systematically investigated in this study. Results proved that tablets can be made from paper, independent of the type of paper used. The tablets appear shiny and with a smooth surface. The pharmaceutical quality was acceptable, i.e. all tablets fulfilled the requirements for tablets according to the European Pharmacopeia. Drug-loaded tablets were produced by compression of drug-loaded paper. Drug loading did not alter the pharmaceutical quality. However, the uncoated tablets possessed an extremely fast disintegration, i.e. intense swelling upon contact with water, which might hamper the swallowing after oral administration. To avoid swelling tablets were successfully coated with a polymer film, leading to a prevention of swelling but immediate disintegration in simulated gastric fluid. In fact, tablets made from paper are a novel and promising strategy for improved oral drug delivery. They can be easily produced without any further excipients and possess pharmaceutical quality according to the European Pharmacopeia.

Electrohydrodynamic atomization and spray-drying for the production of pure drug nanocrystals and co-crystals

In recent years, nanotechnology has offered attractive opportunities to overcome the (bio)pharmaceutical drawbacks of most drugs such as low aqueous solubility and bioavailability. Among the numerous methodologies that have been applied to improve drug performance, a special emphasis has been made on those that increase the dissolution rate and the saturation solubility by the reduction of the particle size of pure drugs to the nanoscale and the associated increase of the specific surface area. Different top-down and bottom-up methods have been implemented, each one with its own pros and cons. Over the last years, the latter that rely on the dissolution of the drug in a proper solvent and its crystallization or co-crystallization by precipitation in an anti-solvent or, conversely, by solvent evaporation have gained remarkable impulse owing to the ability to adjust features such as size, size distribution, morphology and to control the amorphous/crystalline nature of the product. In this framework, electrohydrodynamic atomization (also called electrospraying) and spray-drying excel due to their simplicity and potential scalability. Moreover, they do not necessarily require suspension stabilizers and dry products are often produced during the formation of the nanoparticles what ensures physicochemical stability for longer times than liquid products. This review overviews the potential of these two technologies for the production of pure drug nanocrystals and co-crystals and discusses the recent technological advances and challenges for their implementation in pharmaceutical research and development.

Supercritical carbon dioxide-based technologies for the production of drug nanoparticles/nanocrystals - A comprehensive review

Low drug bioavailability, which is mostly a result of poor aqueous drug solubilities and of inadequate drug dissolution rates, is one of the most significant challenges that pharmaceutical companies are currently facing, since this may limit the therapeutic efficacy of marketed drugs, or even result in the discard of potential highly effective drug candidates during developmental stages. Two of the main approaches that have been implemented in recent years to overcome poor drug solubility/dissolution issues have frequently involved drug particle size reduction (i.e., micronization/nanonization) and/or the modification of some of the physicochemical and structural properties of poorly water soluble drugs. A large number of particle engineering methodologies have been developed, tested, and applied in the synthesis and control of particle size/particle-size distributions, crystallinities, and polymorphic purities of drug micro- and nano-particles/crystals. In recent years pharmaceutical processing using supercritical fluids (SCF), in general, and supercritical carbon dioxide (scCO₂), in particular, have attracted a great attention from the pharmaceutical industry. This is mostly due to the several well-known advantageous technical features of these processes, as well as to other increasingly important subjects for the pharmaceutical industry, namely their "green", sustainable, safe and "environmentally-friendly" intrinsic characteristics. In this work, it is presented a comprehensive state-of-the-art review on scCO₂-based processes focused on the formation and on the control of the physicochemical, structural and morphological properties of amorphous/crystalline pure drug nanoparticles. It is presented and discussed the most relevant scCO₂, scCO₂-based fluids and drug physicochemical properties that are pertinent for the development of successful pharmaceutical products, namely those that are critical in the selection of an adequate scCO₂-based method to produce pure drug nanoparticles/nanocrystals. scCO₂-based nanoparticle formation methodologies are classified in three main families, and in terms of the most important role played by scCO₂ in particle formation processes: as a solvent; as an antisolvent or a co-antisolvent; and as a "high mobility" additive (a solute, a co-solute, or a co-solvent). Specific particle formation methods belonging to each one of these families are presented, discussed and compared. Some selected amorphous/crystalline drug nanoparticles that were prepared by these methods are compiled and presented, namely those studied in the last 10-15 years. A special emphasis is given to the formation of drug cocrystals. It is also discussed the fundamental knowledge and the main mechanisms in which the scCO₂-based particle formation methods rely on, as well as the current status and urgent needs in terms of reliable experimental data and of robust modeling approaches. Other addressed and discussed topics include the currently available and the most adequate physicochemical, morphological and biological characterization methods required for pure drug nanoparticles/nanocrystals, some of the current nanometrology and regulatory issues associated to the use of these methods, as well as some scale-up, post-processing and pharmaceutical regulatory subjects related to the industrial implementation of these scCO₂-based processes. Finally, it is also discussed the current status of these techniques, as well as their future major perspectives and opportunities for industrial implementation in the upcoming years.

Practical guidelines for the characterization and quality control of pure drug nanoparticles and nano-cocrystals in the pharmaceutical industry

The number of poorly soluble drug candidates is increasing, and this is also seen in the research interest towards drug nanoparticles and (nano-)cocrystals; improved solubility is the most important application of these nanosystems. In order to confirm the functionality of these nanoparticles throughout their lifecycle, repeatability of the formulation processes, functional performance of the formed systems in pre-determined way and system stability, a thorough physicochemical understanding with the aid of necessary analytical techniques is needed. Even very minor deviations in for example particle size or size deviation in nanoscale can alter the product bioavailability, and the effect is even more dramatic with the smallest particle size fractions. Also, small particle size sets special requirements for the analytical techniques. In this review most important physicochemical properties of drug nanocrystals and nano-cocrystals are presented, suitable analytical techniques, their pros and cons, are described with the extra input on practical point of view.

Strategies for the enhanced intracellular delivery of nanomaterials

The intracellular delivery of nanomaterials and drugs has been attracting increasing research interest, mainly because of their important effects and functions in several organelles. Targeting specific organelles can help treat or decrease the symptoms of diabetes, cancer, infectious, and autoimmune diseases. Tuning biological and chemical properties enables the creation of functionalized nanomaterials with enhanced intracellular uptake, ability to escape premature lysosome degradation, and to reach a specific target. Here, we provide an update of recent advances in the intracellular delivery mechanisms that could help drugs reach their target more efficiently.

Nanocrystals for improved dermal drug delivery

Nanocrystals are composed of 100% active and possess an increased aqueous solubility and dissolution velocity when compared to larger sized materials. Nanocrystals can be used to improve the bioavailability of poorly soluble actives not only for oral, but also for topical application. In this study nanocrystals of different sizes were produced and the influence of size on dermal penetration was investigated. The influence of different excipients and vehicles on the penetration efficacy upon dermal application was also investigated. Results confirm that dermal penetration of poorly soluble actives increases with decreasing size of the nanocrystals. Unexpectedly, it was observed that many classical penetration enhancers failed to promote the penetration of actives from nanocrystals. Also hydrogels were found to be non-suitable vehicles for the formulation of nanocrystals. As most suitable vehicles for nanocrystals oleogels and creams were identified.

Modifying the physicochemical properties of NSAIDs for nasal and pulmonary administration

This review focuses on nasal and pulmonary delivery of NSAIDs (non-steroidal anti-inflammatory drugs) for fast-onset analgesia, for the potential prevention of Alzheimer's disease (AD), as well as for an add-on treatment in cystic fibrosis (CF) and non-small cell lung cancer (NSCLC). I discuss how the physicochemical properties of NSAIDs can be modified with respect to the biological characteristics of the target site. Innovative technology and/or dosage forms can promote an effective therapy.

Cabotegravir in the treatment and prevention of Human Immunodeficiency Virus-1

INTRODUCTION

Human Immunodeficiency Virus (HIV) is a chronic infection that depletes the immune system of essential components causing those infected to be at risk for multiple life-threatening infections. Worldwide, millions live with this infection, the vast majority attributable to HIV-1. Transmission persists with hundreds of thousands of new infections reported yearly. Implementation of combination antiretroviral therapy (cART) has been effective in improving outcomes and decreasing transmission. Newer co-formulated agents have provided simpler medication regimens, fewer side effects, and, in some cases, a higher barrier to the emergence of medication resistance. Areas covered: Here, we review trials of cabotegravir (CAB) as treatment of HIV-1 infection and its potential use as pre-exposure prophylaxis (PrEP) in high risk individuals, including issues around oral lead in and potential resistance emergence. Expert opinion: CAB is efficacious when used in combination therapy orally or given intramuscularly every 4 to 8 weeks. Its availability in a long-acting injectable formulation (CAB-LA) makes it a valuable, novel drug to treat HIV-1 infection when combined with long-acting injectable rilpivirine (RPV-LA). Moreover, pre-clinical and early Phase 2a studies support its testing as monotherapy as PrEP. Studies are underway comparing the efficacy of every 8 week CAB-LA to tenofovir disoproxil fumarate/emtricitabine (TDF/FTC).

A Comparative In Vivo Study of Albumin-Coated Paclitaxel Nanocrystals and Abraxane

Nanoparticulate drug carriers exploit the enhanced permeability of tumor vasculature to achieve selective delivery of chemotherapeutic drugs. For this purpose, nanoparticles (NPs) need to circulate with a long half-life, enter tumors via the permeable vasculature and stay in tumors via favorable interactions with tumor cells. To fulfill these requirements, albumin-coated nanocrystal formulation of paclitaxel (PTX), Cim-F-alb, featuring high drug loading content, physical stability in serum, and surface-bound albumin in its native conformation is prepared. The pharmacokinetic and biodistribution (PK/BD) profiles of Cim-F-alb in a mouse model of B16F10 melanoma show that Cim-F-alb exhibits a longer plasma half-life and a greater PTX deposition in tumors than Abraxane by ≈1.5 and ≈4.6 fold, respectively. Biolayer interferometry analysis indicates that Cim-F-alb has less interaction with serum proteins than nanocrystals lacking albumin coating, indicating the protective effect of the surface-bound albumin against opsonization in the initial deposition phase. With the advantageous PK/BD profiles, Cim-F-alb shows greater and longer-lasting anticancer efficacy than Abraxane at the equivalent dose. This study demonstrates the significance of controlling circulation stability and surface property of NPs in efficient drug delivery to tumors and enhanced anticancer efficacy.