BCS class IV drugs: Highly notorious candidates for formulation development

Toward a better understanding of metabolic and pharmacokinetic characteristics of low-solubility, low-permeability natural medicines

Today, it is very challenging to develop new active pharmaceutical ingredients. Developing good preparations of well-recognized natural medicines is certainly a practical and economic strategy. Low-solubility, low-permeability natural medicines (LLNMs) possess valuable advantages such as effectiveness, relative low cost and low toxicity, which is shown by the presence of popular products on the market. Understanding the in vivo metabolic and pharmacokinetic characteristics of LLNMs contributes to overcoming their associated problems, such as low absorption and low bioavailability. In this review, the structure-based metabolic reactions of LLNMs and related enzymatic systems, cellular and bodily pharmacological effects and metabolic influences, drug-drug interactions involved in metabolism and microenvironmental changes, and pharmacokinetics and dose-dependent/linear pharmacokinetic models are comprehensively evaluated. This review suggests that better pharmacological activity and pharmacokinetic behaviors may be achieved by modifying the metabolism through using nanotechnology and nanosystem in combination with the suitable administration route and dosage. It is noteworthy that novel nanosystems, such as triggered-release liposomes, nucleic acid polymer nanosystems and PEGylated dendrimers, in addition to prodrug and intestinal penetration enhancer, demonstrate encouraging performance. Insights into the metabolic and pharmacokinetic characteristics of LLNMs may help pharmacists to identify new LLNM formulations with high bioavailability and amazing efficacy and help physicians carry out LLNM-based precision medicine and individualized therapies.

Identification of a previously unreported co-crystal form of acetazolamide: a combination of multiple experimental and virtual screening methods

In this work, we demonstrate an approach of trying multiple methods in a more comprehensive search for co-crystals of acetazolamide.

Transdermal delivery of nobiletin using ionic liquids

Nobiletin (NOB), a flavonoid, has extremely low water solubility and low oral bioavailability; however, despite these problems, various physiological effects have been investigated in vitro. In the present study, we investigated the transdermal delivery of NOB using choline and geranic acid (CAGE), which is a biocompatible material that has been reported to be a promising transdermal delivery approach. The feasibility was evaluated by a set of in vitro and in vivo tests. A solubility evaluation demonstrated that CAGE induced excellent solubility of NOB induced by multipoint hydrogen bonding between NOB and CAGE. In vitro transdermal tests using a Franz diffusion cell showed that CAGE was effective in enhancing transdermal absorption of NOB, compared to other penetration enhancers. Subsequent in vivo tests demonstrated that CAGE significantly improved area under the concentration-time curve of NOB in vivo and NOB/CAGE sample showed 20-times higher bioavailability than oral administration of NOB crystal. Furthermore, NOB/CAGE sample also showed significant drops of the blood glucose level in rats derived from hypoglycemic activity of NOB. Thus, transdermal administration of NOB using CAGE was shown to be feasible, which indicates that the use of CAGE may be adapted for other flavonoids that also show both low water solubility and low permeability.

An Investigation into the Factors Governing Drug Absorption and Food Effect Prediction Based on Data Mining Methodology

Drug absorption is a complex process governed by a number of interrelated physicochemical, biopharmaceutical, and pharmacokinetic factors. In order to explore complex relationships among these factors, multivariate exploratory analysis was performed on the dataset of drugs with diverse bioperformance. The investigated dataset included subset of drugs for which bioequivalence between solid dosage form and oral solution has been reported, and subset of drugs described in the literature as low solubility/low permeability compounds. Discriminatory power of hierarchical clustering on principal components was somewhat higher when applied on the data subsets of drugs with similar bioperformance, while analysis of the integrated dataset indicated existence of two groups of drugs with the boundaries reflected in P_eff value of approximately 2 × 10^-4 cm/s and Fa and Fm values higher than 85% and 50%, respectively. Majority of the investigated drugs within the integrated dataset were grouped within their initial subset indicating that overall drug bioperformance is closely related to its physicochemical, biopharmaceutical and pharmacokinetic properties. Classification models constructed using the random forest (RF) and support vector machine with polynomial kernel function were able to predict food effect based on drug dose/solubility ratio (D/S), effective permeability (P_eff), percent of dose metabolized (Fm), and elimination half-life (τ_1/2). Although both models performed well during training and testing, only RF kept satisfying performance when applied on the external dataset (kappa value > 0.4). The results obtained indicate that data mining can be employed as useful tool in biopharmaceutical drug characterization which merits further investigation.

Co-encapsulation of docetaxel and cyclosporin A into SNEDDS to promote oral cancer chemotherapy

Self-nanoemulsifying drug delivery system (SNEDDS) have been considered as a promising platform for oral delivery of many BCS (biopharmaceutics classification system) class IV drugs, such as docetaxel (DTX). However, oral chemotherapy with DTX is also restricted by its active P-glycoprotein (P-gp) efflux and hepatic first-pass metabolism. To address these challenges, we developed a novel SNEDDS co-loaded with DTX and cyclosporine A (CsA) to achieve effective inhibition of P-gp efflux and P450 enzyme metabolization, improving oral bioavailability of DTX. The SNEDDS showed uniform droplet size of about 30 nm. Additionally, the prepared SNEDDS exhibited a sequential drug release trend of CsA prior to DTX. The intestinal experiments confirmed that the membrane permeability of DTX was significantly increased in the whole intestinal tract, especially in the jejunum segment. Furthermore, the oral bioavailability of co-loaded SNEDDS was 9.2-fold and 3.4-fold higher than DTX solution and DTX SNEDDS, respectively. More importantly, it exhibited a remarkable antitumor efficacy with a reduced toxicity compared with intravenously administered DTX solution. In summary, DTX-CsA co-loaded SNEDDS is a promising platform to facilitate oral docetaxel-based chemotherapy.

The Grouping and Assessment Strategy for Organic Pigments (GRAPE): Scientific evidence to facilitate regulatory decision-making

This article presents the Grouping and Assessment Strategy for Organic Pigments (GRAPE). GRAPE is driven by the hypotheses that low (bio)dissolution and low permeability indicate absence of systemic bioavailability and hence no systemic toxicity potential upon oral exposure, and, for inhalation exposure, that low (bio)dissolution (and absence of surface reactivity, dispersibility and in vitro effects) indicate that the organic pigment is a 'poorly soluble particle without intrinsic toxicity potential'. In GRAPE Tier 1, (bio)solubility and (bio)dissolution are assessed, and in Tier 2, in vitro Caco-2 permeability and in vitro alveolar macrophage activation. Thereafter, organic pigments are grouped by common properties (further considering structural similarity depending on the regulatory requirements). In Tier 3, absence of systemic bioavailability is verified by limited in vivo screening (rat 28-day oral and 5-day inhalation toxicity studies). If Tier 3 confirms no (or only very low) systemic bioavailability, all higher-tier endpoint-specific animal testing is scientifically not-relevant. Application of the GRAPE can serve to reduce animal testing needs for all but few representative organic pigments within a group. GRAPE stands in line with the EU REACH Regulation (Registration, Evaluation, Authorisation and Restriction of Chemicals). An ongoing research project aims at establishing a proof-of-concept of the GRAPE.

Oral delivery of paclitaxel by polymeric micelles: A comparison of different block length on uptake, permeability and oral bioavailability

Drug solubility and permeability are two major challenges affecting oral delivery, the most popular route of drug administration. Polymeric micelles is an emerging technology for overcoming the current oral drug delivery hurdles. Previous study primarily focused on developing new polymers or new micellar systems and a systematic investigation of the impact of the polymer block length on solubility and permeability enhancement; and their subsequent effect on oral bioavailability is lacking. Herein, by using paclitaxel, a poorly soluble P-glycoproteins (P-gp) substrate, as a model, we aim to assess and compare the drug-loaded micelles prepared with two different molecular weight of poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL), with the ultimate goal of establishing a strong scientific rationale for proper design of formulations for oral drug delivery. PEG-b-PCL (750:570) (PEG₁₇-b-PCL₅) and PEG-b-PCL (5k:10k) (PEG₁₁₄-b-PCL₈₈) effectively enhanced the solubility of paclitaxel compared to the free drug. PEG-b-PCL (750:570) increased both P-gp and non P-gp substrate cellular uptake and increased the apparent permeability coefficient of a P-gp substrate. In vivo animal study showed that PEG-b-PCL micelles efficiently enhanced the oral bioavailability of paclitaxel. In addition to solubility enhancement, polymer choice also plays a pivotal role in determining the oral bioavailability improvement, probably via permeation enhancement. In conclusion, the knowledge gained in this study enables rational design of polymeric micelles to overcome the current challenges of oral drug delivery and it also provides a basis for future clinical translation of the technology.

Evaluation of Oleic Acid and Polyethylene Glycol Monomethyl Ether Conjugate (PEGylated Oleic Acid) as a Solubility Enhancer of Furosemide

Poor aqueous solubility limits the therapeutic efficacy of many marketed and investigational drugs. Synthesis of new drugs with improved solubility is challenging due to time constraint and expenses involved. Therefore, finding the solubility enhancers for existing drugs is an attractive and profitable strategy. In this study, PEGylated oleic acid (OA-mPEG5000), a conjugate of oleic acid and mPEG5000 was synthesized and evaluated as a solubilizer for furosemide. OA-mPEG5000 was evaluated as a nanocarrier for furosemide by formulating polymersomes. Solubility of furosemide in milli-Q water and aqueous OA-mPEG5000 solution was determined using shake flask method. At 37 °C, the solubility of furosemide in OA-mPEG5000 (1% w/w) and milli-Q water was 3404.7 ± 254.6 µg/mL and 1020.2 ± 40.9 µg/mL, respectively. Results showed there was a 3.34-fold increase in solubility of furosemide in OA-mPEG5000 compared to water at 37 °C. At 25 °C, there was a 3.31-fold increase in solubilization of furosemide in OA-mPEG5000 (1% w/w) (90.0 ± 1.45 µg/mL) compared to milli-Q water (27.2 ± 1.43 µg/mL). Size, polydispersity index and zeta potential of polymersomes ranged from 85–145.5 nm, 0.187–0.511 and −4.0–12.77 mV, respectively. In-vitro release study revealed a burst release (71%) within 1 h. Significant enhancement in solubility and formation of polymersomes suggested that OA-mPEG5000 could be a good solubilizer and nanocarrier for furosemide.

Paclitaxel-encapsulated core–shell nanoparticle of cetyl alcohol for active targeted delivery through oral route

Aim: Paclitaxel (PTX) has no clinically available oral formulations. Cetyl alcohol is metabolized by alcohol dehydrogenase and aldehyde dehydrogenase that are overexpressed in cancer cells. So, PTX-encapsulated core–shell nanoparticle of cetyl alcohol (PaxSLN) could target the cancer cells through oral route. Materials & methods: PaxSLN was synthesized using microemulsion template. Efficiency of PaxSLN was evaluated by ALDEFLUOR™, multicellular tumor spheroid formation inhibition assays and CT26 colorectal carcinoma animal model. Pharmacokinetics and biodistribution studies were done in Sprague Dawley rats. Results: PTX was encapsulated at the core of approximately 78 nm PaxSLN. PaxSLN targeted aldehyde dehydrogenase overexpressing cells. Its oral bioavailability was approximately 95% and chemotherapeutic efficacy was better than Taxol® and nab-PTX. Conclusion: A novel oral nanoformulation of PTX was developed.

Development of microparticles coated with poly-γ-glutamic acid to improve oral absorption of a poorly water-soluble drug

Novel microparticles coated with poly-γ-glutamic acid (PGA) were developed to improve the oral absorption of indomethacin (IM), a poorly water-soluble drug. Microparticles containing γ-IM (IM_bulk-PGA) or crystal polymorph α-IM (IM_polymorph-PGA) were prepared. Additionally, microparticles were prepared containing α-IM without PGA (IM_polymorph without PGA). IM_bulk-PGA and IM_polymorph-PGA exhibited better drug retention properties on mucin disks. Drug release rates from IM_polymorph-PGA and IM_polymorph without PGA were higher than from IM bulk powder, and drug release from IM_bulk-PGA was also improved. Drug release from IM_bulk-PGA could be improved with the use of Tween 80. In addition, PGA may influence the ionization of IM or affect specific molecular interactions. After the microparticles were administered orally to mice, IM_bulk-PGA and IM_polymorph-PGA increased the plasma drug concentration more rapidly compared with IM bulk powder, but IM_polymorph without PGA did not increase the plasma drug concentration. It was considered that IM_bulk-PGA and IM_polymorph-PGA rapidly reached the intestinal membrane through the mucus layer and IM was absorbed quickly. Because IM_bulk-PGA and IM_polymorph-PGA showed a rapid increase in plasma drug concentration, IM_bulk-PGA and IM_polymorph-PGA could be useful preparations to improve the gastrointestinal absorption of IM. Furthermore, IM_bulk-PGA may maintain higher plasma drug concentrations than IM_polymorph-PGA.

Formulating a single thioether-bridged oleate prodrug into a self-nanoemulsifying drug delivery system to facilitate oral absorption of docetaxel

Oral chemotherapy of docetaxel (DTX) is restricted by active P-glycoprotein (P-gp) efflux, hepatic first-pass metabolism and then poor oral absorption. Herein, a lipophilic thioether-bridged oleate prodrug (DTX-S-OA) and an ester-bond linked oleate prodrug of docetaxel (DTX-OA) were synthesized and efficiently incorporated into a self-nanoemulsifying drug delivery system (SNEDDS) using core-matching technology with a high drug-loading rate. DTX-S-OA SNEDDS produced a uniform droplet size of about 30 nm and a significantly high drug loading capability (60 mg mL-1), compared with DTX SNEDDS (20 mg mL-1). Additionally, DTX-S-OA SNEDDS exhibited a markedly slower drug release property and higher (>2-fold) drug solubilization in the aqueous phase after 60 min lipolysis compared with DTX SNEDDS. In situ single-pass intestinal perfusion and intestinal biodistribution studies demonstrated that the membrane permeability and intestinal bioadhesion of SNEDDS were significantly increased. Moreover, DTX-S-OA showed a comparable ability with verapamil in inhibiting P-gp efflux. Lymphatic transport studies confirmed that DTX-S-OA SNEDDS could significantly enhance intestinal lymphatic transport. Notably, the bioavailability of DTX-S-OA SNEDDS was 6.2-fold and 2.0-fold higher than that of the DTX solution and DTX SNEDDS, respectively. Furthermore, DTX-S-OA achieved a more rapid release of free DTX from the prodrug in systemic circulation than DTX-OA. Therefore, such a unique combination strategy of the single thioether-bridged DTX-oleate prodrug and SNEDDS is a promising platform to enable effective oral delivery of DTX.

Systemic Design and Evaluation of Ticagrelor-Loaded Nanostructured Lipid Carriers for Enhancing Bioavailability and Antiplatelet Activity

Ticagrelor (TGL), a P2Y12 receptor antagonist, is classified as biopharmaceutics classification system (BCS) class IV drug due to its poor solubility and permeability, resulting in low oral bioavailability. Nanostructured lipid carriers (NLC) are an efficient delivery system for the improvement of bioavailability of BCS class IV drugs. Hence, we prepared TGL-loaded NLC (TGL-NLC) to enhance the oral bioavailability and antiplatelet activity of TGL with a systemic design approach. The optimized TGL-NLC with Box-Behnken design showed a small particle size of 87.6 nm and high encapsulation efficiency of 92.1%. Scanning electron microscope (SEM), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD) were performed to investigate the characteristics of TGL-NLC. Furthermore, TGL-NLC exhibited biocompatible cytotoxicity against Caco-2 cells. Cellular uptake of TGL-NLC was 1.56-fold higher than that of raw TGL on Caco-2 cells. In pharmacokinetic study, the oral bioavailability of TGL-NLC was 254.99% higher than that of raw TGL. In addition, pharmacodynamic study demonstrated that the antiplatelet activity of TGL-NLC was superior to that of raw TGL, based on enhanced bioavailability of TGL-NLC. These results suggest that TGL-NLC can be applied for efficient oral absorption and antiplatelet activity of TGL.

The nested enzyme-within-enterocyte (NEWE) turnover model for predicting dynamic drug and disease effects on the gut wall

Physiologically-based pharmacokinetic (PBPK) models provide a framework for in vitro-in vivo extrapolation of metabolic drug clearance. Many of the concepts in PBPK can have consequential impact on more mechanistic systems pharmacology models. In the gut wall, turnover of enzymes and enterocytes are typically lumped into one rate constant that describes the time dependent enzyme activity. This assumption may influence predictability of any sustained and dynamic effects such as mechanism-based inhibition (MBI), particularly when considering translation from healthy to gut disease. A novel multi-level systems PBPK model was developed. This model comprised a 'nested enzyme-within enterocyte' (NEWE) turnover model to describe levels of drug-metabolising enzymes. The ability of the model to predict gut metabolism following MBI and gut disease was investigated and compared to the conventional modelling approach. For MBI, the default NEWE model performed comparably to the conventional model. However, when drug-specific spatial crypt-villous absorption was considered, up to approximately 50% lower impact of MBI was simulated for substrates highly metabolised by cytochrome P450 (CYP) 3A4, interacting with potent inhibitors. Further, the model showed potential in predicting the disease effect of gastrointestinal mucositis and untreated coeliac disease when compared to indirect clinical pharmacokinetic parameters. Considering the added complexity of the NEWE model, it does not provide an attractive solution for improving upon MBI predictions in healthy individuals. However, nesting turnover may enable extrapolation to gut disease-drug interactions. The principle detailed herein may be useful for modelling drug interactions with cellular targets where turnover is significant enough to affect this process.

Submission of Rifaximin to Different Techniques: Characterization, Solubility Study, and Microbiological Evaluation

Rifaximin, an oral antimicrobial drug, is marketed as 200-mg tablets. The daily dose ranges from 600 mg (1 tablet 3 times a day) to 800 mg (2 tablets twice a day). It is used for a wide range of ages, from adults to children, since it is indicated for the treatment of hepatic encephalopathy, travelers' diarrhea, irritable bowel syndrome, Clostridium difficile, ulcerative colitis, and acute diarrhea. The success of pharmacotherapy will depend on correct fulfillment of drug administration; however, it becomes difficult when the tablets are large and the doses are frequent. Rifaximin belongs to class IV according to the Biopharmaceutic Classification System (BCS), meaning that it is both poorly soluble and poorly permeable. Thus, in this study, solubility of rifaximin was improved by its complexation to β-cyclodextrin by (i) phase solubility diagram, (ii) malaxation, and (iii) decreasing particle size by wet milling. Improved solubility provides lower doses and facilitates compliance with pharmacotherapy. The products formed were analyzed by spectrophotometry in the infrared region (FT-IR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). Also, their solubility and microbiological activity were determined. The products obtained in all techniques were more soluble than the free drug; they presented higher thermal stability and antimicrobial potency was approximately 100% with all the formulations. It is important to highlight that the treatment failure not only affects the quality of life of the patients, but also contributes significantly to the economic burden of the health system. Therefore, these findings are extremely interesting, both from a technological and financial point of view.

Surfactant-free solid dispersion of BCS class IV drug in an amorphous chitosan oligosaccharide matrix for concomitant dissolution in vitro - permeability increase

Saccharides have been applied as a water-soluble matrix for dispersing hydrophobic drugs homogeneously without the need to use surfactants in amorphous solid dispersions (ASD). Up to now, concomitant permeability improvement of BCS Class IV drug by such matrices have not been much appreciated. Herein, an amorphous chitosan oligosaccharide (COS) was used as matrix to prepare surfactant-free ASD of BCS class IV drug by the ball milling method, with curcumin (CUR) as a model drug. The DSC, XRPD, FTIR and physical stability experiments indicated that CUR was in an amorphous state with high physical stability and exhibited potential interactions with COS in the ASD. Non-sink dissolution in vitro studies showed the maximum dissolution concentration of all CUR-COS ASD (CUR and COS at weight ratios of 1:1, 1:2 and 1:4) reached ranging from 97.85 to 101.21 μg/mL, far above that of pure CUR. The supersaturated concentration remained for at least 24 h under non-sink condition. Caco-2 cell model revealed that, compared to the pure CUR group, the apparent permeability coefficients were increased by 1.72-4.44-fold in all three CUR-COS ASD, which was mainly attributed to opening the tight junctions of Caco-2 cells by COS. The pharmacokinetic study showed that all CUR-COS ASD groups exhibited significant enhancements in AUC_0-∞, with 1.55-3.01-fold that of pure CUR (p < 0.01). T_max of CUR was shortened after oral administration of all three ASD. The current study demonstrates the amorphous COS could be used as a promising matrix in ASD for enhancing the oral bioavailability of BCS class IV drug by improving dissolution behavior and membrane permeability.

Hybrid mesoporous nanorods with deeply grooved lateral faces toward cytosolic drug delivery

Hybrid mesoporous nanorods with six twisted sharp edges can induce effective penetration of intracellular barriers and cytosolic delivery of membrane-impermeable drugs through curvature effects.

Simultaneously enhancing the in vitro/in vivo performances of acetazolamide using proline as a zwitterionic coformer for cocrystallization

The synthesized first acetazolamide zwitterionic cocrystal highlights simultaneously-increasing solubility and permeability of acetazolamide, which successfully translate into enhanced bioavailability.

Exploring an interesting dual functionality of anacardic acid for efficient paclitaxel delivery in breast cancer therapy

Aim: To explore the potential of paclitaxel (PTX)-loaded anacardic acid conjugated hydrophobized gelatin nanoparticles. Materials & methods: Nanoparticles prepared by nanoprecipitation technique were evaluated for various quality attributes (particle size, % entrapment efficiency) in vitro drug release, MCF-7 cell uptake, cell cytotoxicity, in vivo pharmacokinetics, antitumor efficacy and toxicity. Results: The nanoparticles (250–300 nm, 74% entrapment efficiency) showed approximately 2.26-fold higher apoptosis index and approximately 5.86-fold reduction in IC50 value compared with PTX in MCF-7 cells. Also, approximately 3.51- and 1.36-fold increase in area under the curve compared with Intaxel® and Nanoxel™ (both from Fresenius Kabi, Gurugram, India) was achieved. Significant tumor burden reduction (∼60%) and reduced toxicity was observed compared with marketed formulations. Conclusion: The hydrophobized gelatin nanoparticles displayed promising therapeutic potential, paving a new path for efficient PTX delivery.

Enhanced Solubility, Permeability and Anticancer Activity of Vorinostat Using Tailored Mesoporous Silica Nanoparticles

Suberoylanilide hydroxamic acid (SAHA) or vorinostat (VOR) is a potent inhibitor of class I histone deacetylases (HDACs) that is approved for the treatment of cutaneous T-cell lymphoma. However, it has the intrinsic limitations of low water solubility and low permeability which reduces its clinical potential especially when given orally. Packaging of drugs within ordered mesoporous silica nanoparticles (MSNs) is an emerging strategy for increasing drug solubility and permeability of BCS (Biopharmaceutical Classification System) class II and IV drugs. In this study, we encapsulated vorinostat within MSNs modified with different functional groups, and assessed its solubility, permeability and anti-cancer efficacy in vitro. Compared to free drug, the solubility of vorinostat was enhanced 2.6-fold upon encapsulation in pristine MSNs (MCM-41-VOR). Solubility was further enhanced when MSNs were modified with silanes having amino (3.9 fold) or phosphonate (4.3 fold) terminal functional groups. Moreover, permeability of vorinostat into Caco-2 human colon cancer cells was significantly enhanced for MSN-based formulations, particularly MSNs modified with amino functional group (MCM-41-NH₂-VOR) where it was enhanced ~4 fold. Compared to free drug, vorinostat encapsulated within amino-modified MSNs robustly induced histone hyperacetylation and expression of established histone deacetylase inhibitor (HDACi)-target genes, and induced extensive apoptosis in HCT116 colon cancer cells. Similar effects were observed on apoptosis induction in HH cutaneous T-cell lymphoma cells. Thus, encapsulation of the BCS class IV molecule vorinostat within MSNs represents an effective strategy for improving its solubility, permeability and anti-tumour activity.

Chelation, formulation, encapsulation, retention, and in vivo biodistribution of hydrophobic nanoparticles labelled with 57Co-porphyrin: Oleylamine ensures stable chelation of cobalt in nanoparticles that accumulate in tumors

BACKGROUND AND MOTIVATION

While small molecules can be used in cancer diagnosis there is a need for imageable diagnostic NanoParticles (NPs) that act as surrogates for the therapeutic NPs. Many NPs are composed of hydrophobic materials so the challenge is to formulate hydrophobic imaging agents. To develop individualized medical treatments based on NP, a first step should be the selection of patients who are likely responders to the treatment as judged by imaging tumor accumulation of NPs. This requires NPs with the same size and structure as the subsequent therapeutic NPs but labelled with a long-lived radionuclide. Cobalt isotopes are good candidates for NP labelling since ⁵⁵Co has half-life of 17.5 h and positron energy of 570 keV while ⁵⁷Co (t_1/2 271.6 d) is an isotope suited for preclinical single photon emission tomography (SPECT) to visualize biodistribution and pharmacokinetics of NPs. We used the hydrophobic octaethyl porphyrin (OEP) to chelate cobalt and to encapsulate it inside hydrophobic liquid NPs (LNPs). We hypothesized that at least two additional hydrophobic axial ligands (oleylamine, OA) must be provided to the OEP-Co complex in order to encapsulate and retain Co inside LNP.

RESULTS

1. Cobalt chelation by OEP and OA. The association constant of cobalt to OEP was 2.49 × 10⁵ M^-1 and the formation of the hexacoordinate complex OEP-Co-4OA was measured by spectroscopy. 2. NP formulation and characterization: LNPs were prepared by the fast ethanol injection method and were composed of a liquid core (triolein) surrounded by a lipid monolayer (DSPC:Cholesterol:DSPE-PEG₂₀₀₀). The size of the LNPs loaded with the cobalt complex was 40 ± 5 nm, 3. Encapsulation of OEP-Co-OA: The loading capacity of OEP-Co-OA in LNP was 5 mol%. 4. Retention of OEP-⁵⁷Co-4OA complex in the LNPs: the positive effect of the OA ligands was demonstrated on the stability of the OEP-⁵⁷Co-4OA complex, providing a half-life for retention in PBS of 170 h (7 days) while in the absence of the axial OA ligands was only 22 h. 5 Biodistribution Study: the in vivo biodistribution of LNP was studied in AR42J pancreatic tumor-bearing mice. The estimated half-life of LNPs in blood was about 7.2 h. Remarkably, the accumulation of LNPs in the tumor was as high as 9.4% ID/g 24 h after injection with a doubling time for tumor accumulation of 3.22 h. The most important result was that the nanoparticles could indeed accumulate in the AR42J tumors up to levels greater than those of other NPs previously measured in the same tumor model, and at about half the values reported for the molecular agent ⁵⁷Co-DOTATATE.

CONCLUSIONS

The additional hydrophobic chelator OA was indeed needed to obtain a stable octahedral OEP-Co-4OA. Cobalt was actually well-retained inside LNP in the OEP-Co-4OA complex. The method described in the present work for the core-labelling of LNPs with cobalt is now ready for labeling of NPs with ⁵⁵Co, or indeed other hexadentate radionuclides of interest for preclinical in vivo PET-imaging and radio-therapeutics.

A New Strategy for Intestinal Drug Delivery via pH-Responsive and Membrane-Active Nanogels

Oral administration of hydrophobic and poorly intestinal epithelium-permeable drugs is a significant challenge. Herein, we report a new strategy to overcome this problem by using novel, pH-responsive, and membrane-active nanogels as drug carriers. Prepared by simple physical cross-linking of amphiphilic pseudopeptidic polymers with pH-controlled membrane-activity, the size and hydrophobicity-hydrophilicity balance of the nanogels could be well-tuned. Furthermore, the amphiphilic nanogels could release hydrophobic payloads and destabilize cell membranes at duodenum and jejunum pH 5.0-6.0, which suggests their great potential for intestinal drug delivery.

Can lifecycle management safeguard innovation in the pharmaceutical industry?

The pharmaceutical industry invests enormous amounts of resources (>€1 billion and >10years) in the development of new products. External factors such as intensifying foreign competition and greater regulatory demands can negatively affect the profit margin, whereas the R&D productivity diminishes. To stay competitive and to maintain high R&D capabilities for developing new medicinal products, companies must make smart investment decisions to maximize their return on investment. Consequently, the entire lifecycle of a medicinal product must be effectively managed to ensure a sustained development through commercialization. This review critically assesses the current situation and the associated management strategies throughout the lifecycle of a medicinal product.

Pharmaceutical Dispersion Techniques for Dissolution and Bioavailability Enhancement of Poorly Water-Soluble Drugs

Over the past decades, a large number of drugs as well as drug candidates with poor dissolution characteristics have been witnessed, which invokes great interest in enabling formulation of these active ingredients. Poorly water-soluble drugs, especially biopharmaceutical classification system (BCS) II ones, are preferably designed as oral dosage forms if the dissolution limit can be broken through. Minimizing a drug’s size is an effective means to increase its dissolution and hence the bioavailability, which can be achieved by specialized dispersion techniques. This article reviews the most commonly used dispersion techniques for pharmaceutical processing that can practically enhance the dissolution and bioavailability of poorly water-soluble drugs. Major interests focus on solid dispersion, lipid-based dispersion (nanoencapsulation), and liquisolid dispersion (drug solubilized in a non-volatile solvent and dispersed in suitable solid excipients for tableting or capsulizing), covering the formulation development, preparative technique and potential applications for oral drug delivery. Otherwise, some other techniques that can increase the dispersibility of a drug such as co-precipitation, concomitant crystallization and inclusion complexation are also discussed. Various dispersion techniques provide a productive platform for addressing the formulation challenge of poorly water-soluble drugs. Solid dispersion and liquisolid dispersion are most likely to be successful in developing oral dosage forms. Lipid-based dispersion represents a promising approach to surmounting the bioavailability of low-permeable drugs, though the technique needs to traverse the obstacle from liquid to solid transformation. Novel dispersion techniques are highly encouraged to develop for formulation of poorly water-soluble drugs.

Recent advances in improving oral drug bioavailability by cocrystals

Introduction: Oral drug delivery is the most favored route of drug administration. However, poor oral bioavailability is one of the leading reasons for insufficient clinical efficacy. Improving oral absorption of drugs with low water solubility and/or low intestinal membrane permeability is an active field of research. Cocrystallization of drugs with appropriate coformers is a promising approach for enhancing oral bioavailability.

Methods: In the present review, we have focused on recent advances that have been made in improving oral absorption through cocrystallization. The covered areas include supersaturation and its importance on oral absorption of cocrystals, permeability of cocrystals through membranes, drug-coformer pharmacokinetic (PK) interactions, conducting in vivo-in vitro correlations for cocrystals. Additionally, a discussion has been made on the integration of nanocrystal technology with supramolecular design. Marketed cocrystal products and PK studies in human subjects are also reported.

Results: Considering supersaturation and consequent precipitation properties is necessary when evaluating dissolution and bioavailability of cocrystals. Appropriate excipients should be included to control precipitation kinetics and to capture solubility advantage of cocrystals. Beside to solubility, cocrystals may modify membrane permeability of drugs. Therefore, cocrystals can find applications in improving oral bioavailability of poorly permeable drugs. It has been shown that cocrystals may interrupt cellular integrity of cellular monolayers which can raise toxicity concerns. Some of coformers may interact with intestinal absorption of drugs through changing intestinal blood flow, metabolism and inhibiting efflux pumps. Therefore, caution should be taken into account when conducting bioavailability studies. Nanosized cocrystals have shown a high potential towards improving absorption of poorly soluble drugs.

Conclusions: Cocrystals have found their way from the proof-of-principle stage to the clinic. Up to now, at least two cocrystal products have gained approval from regulatory bodies. However, there are remaining challenges on safety, predicting in vivo behavior and revealing real potential of cocrystals in the human.

A comparative study between hot-melt extrusion and spray-drying for the manufacture of anti-hypertension compatible monolithic fixed-dose combination products

The purpose of this work was to investigate the application of different advanced continuous processing techniques (hot melt extrusion and spray drying) to the production of fixed-dose combination (FDC) monolithic systems comprising of hydrochlorothiazide and ramipril for the treatment of hypertension. Identical FDC formulations were manufactured by the two different methods and were characterised using powder X-ray diffraction (PXRD) and modulated differential scanning calorimetry (mDSC). Drug dissolution rates were investigated using a Wood's apparatus, while physical stability was assessed on storage under controlled temperature and humidity conditions. Interestingly both drugs were transformed into their amorphous forms when spray dried, however, hydrochlorothiazide was determined, by PXRD, to be partially crystalline when hot melt extruded with either polymer carrier (Kollidon® VA 64 or Soluplus®). Hot melt extrusion was found to result in significant degradation of ramipril, however, this could be mitigated by the inclusion of the plasticizer, polyethylene glycol 3350, in the formulation and appropriate adjustment of processing temperature. The results of intrinsic dissolution rate studies showed that hot-melt extruded samples were found to release both drugs faster than identical formulations produced via spray drying. However, the differences were attributable to the surface roughness of the compressed discs in the Wood's apparatus, rather than solid state differences between samples. After a 60-day stability study spray dried samples exhibited a greater physical stability than the equivalent hot melt extruded samples.

Long-acting injectable atovaquone nanomedicines for malaria prophylaxis

Chemoprophylaxis is currently the best available prevention from malaria, but its efficacy is compromised by non-adherence to medication. Here we develop a long-acting injectable formulation of atovaquone solid drug nanoparticles that confers long-lived prophylaxis against Plasmodium berghei ANKA malaria in C57BL/6 mice. Protection is obtained at plasma concentrations above 200 ng ml-1 and is causal, attributable to drug activity against liver stage parasites. Parasites that appear after subtherapeutic doses remain atovaquone-sensitive. Pharmacokinetic-pharmacodynamic analysis indicates protection can translate to humans at clinically achievable and safe drug concentrations, potentially offering protection for at least 1 month after a single administration. These findings support the use of long-acting injectable formulations as a new approach for malaria prophylaxis in travellers and for malaria control in the field.

Recent Advances in the Application of Vitamin E TPGS for Drug Delivery

D-ɑ-tocopheryl polyethylene glycol succinate (Vitamin E TPGS or TPGS) has been approved by FDA as a safe adjuvant and widely used in drug delivery systems. The biological and physicochemical properties of TPGS provide multiple advantages for its applications in drug delivery like high biocompatibility, enhancement of drug solubility, improvement of drug permeation and selective antitumor activity. Notably, TPGS can inhibit the activity of ATP dependent P-glycoprotein and act as a potent excipient for overcoming multi-drug resistance (MDR) in tumor. In this review, we aim to discuss the recent advances of TPGS in drug delivery including TPGS based prodrugs, nitric oxide donor and polymers, and unmodified TPGS based formulations. These potential applications are focused on enhancing delivery efficiency as well as the therapeutic effect of agents, especially on overcoming MDR of tumors. It also demonstrates that the clinical translation of TPGS based nanomedicines is still faced with many challenges, which requires more detailed study on TPGS properties and based delivery system in the future.

Beyond liposomes: Recent advances on lipid based nanostructures for poorly soluble/poorly permeable drug delivery

Solid lipid nanoparticle (SLN), nanostructured lipid carriers (NLC) and hybrid nanoparticles, have gained increasing interest as drug delivery systems because of their potential to load and release drugs from the Biopharmaceutical classification system (BCS) of class II (low solubility and high permeability) and of class IV (low solubility and low permeability). Lipid properties (e.g. high solubilizing potential, biocompatibility, biotolerability, biodegradability and distinct route of absorption) contribute for the improvement of the bioavailability of these drugs for a set of administration routes. Their interest continues to grow, as translated by the number of patents being field worldwide. This paper discusses the recent advances on the use of SLN, NLC and lipid-polymer hybrid nanoparticles for the loading of lipophilic, poorly water-soluble and poorly permeable drugs, being developed for oral, topical, parenteral and ocular administration, also discussing the industrial applications of these systems. A review of the patents filled between 2014 and 2017, concerning the original inventions of lipid nanocarriers, is also provided.