The effects of pharmaceutical excipients on drug disposition

Stability of Protein Pharmaceuticals: Recent Advances

There have been significant advances in the formulation and stabilization of proteins in the liquid state over the past years since our previous review. Our mechanistic understanding of protein-excipient interactions has increased, allowing one to develop formulations in a more rational fashion. The field has moved towards more complex and challenging formulations, such as high concentration formulations to allow for subcutaneous administration and co-formulation. While much of the published work has focused on mAbs, the principles appear to apply to any therapeutic protein, although mAbs clearly have some distinctive features. In this review, we first discuss chemical degradation reactions. This is followed by a section on physical instability issues. Then, more specific topics are addressed: instability induced by interactions with interfaces, predictive methods for physical stability and interplay between chemical and physical instability. The final parts are devoted to discussions how all the above impacts (co-)formulation strategies, in particular for high protein concentration solutions.'

Plasma disposition and faecal excretion of eprinomectin following subcutaneous administration in Saanen and Alpine goats

Eprinomectin is extensively used in veterinary medicine, particularly in the treatment of internal and external parasites in livestock, including goats. The pharmacokinetic behavior of eprinomectin in plasma and faeces was studied after a single subcutaneous administration in two different goat breeds at a dose of 0.2 mg/kg body weight. The study was conducted on one-year-old female Saanen (n = 8) and Alpine (n = 8) goats in a parallel design. There were no significant differences between Saanen and Alpine goats on the peak plasma concentration (Cmax, 28.59 ± 7.46 ng/mL vs. 37.69 ± 14.89 ng/mL), area under the curve (AUC0-∞, 93.08 ± 11.66 ng.d/mL vs. 116.98 ± 48.36 ng.d/mL), area under the first moment curve (AUMC0-∞, 311.05 ± 67.23 ng.d2/mL vs. 348.25 ± 202.64 ng.d2/mL) and mean residence time (MRT, 3.24 ± 0.77 d vs. 2.74 ± 0.64 d) values. The plasma terminal half-life and the time to reach peak plasma concentration were significantly higher in Saanen goats (T1/2λz, 2.18 ± 0.43 d; Tmax, 1.21 ± 0.25 d) than in Alpine goats (T1/2λz, 1.66 ± 0.41 d; Tmax, 0.79 ± 0.25 d). The results revealed that the plasma concentration of eprinomectin did not differ depending on the breed in Saanen and Alpine goats. However, it was determined that the eprinomectin clearance from the body may vary depending on the breed in goats. The faecal eprinomectin concentration of Saanen and Alpine goats was 90 and 80 times higher than the plasma eprinomectin concentration, respectively. Although high faecal excretion of eprinomectin confers a high efficacy advantage against parasites in the gastrointestinal tract, it may pose an ecotoxicological risk to manure fauna and aquatic organisms with high susceptibility to this compound.

Tigecycline Absorption Improved by Selected Excipients

To investigate the effects of (2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD), (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD), tocopherol polyethylene glycol 1000 succinate (TPGS), sodium desoxycholate (SDOCH), trimethyl chitosan (TMC), and sodium caprate (C10) on the plasma concentration and the oral bioavailability of tigecycline in broiler chickens. To test the effects of the excipients on absorption of tigecycline, a tetracycline that is poorly absorbed from the gastrointestinal tract, broiler chickens were used as an animal model. Tigecycline (10 mg/kg body weight) was administered intravenously, orally, and orally with one of the excipients. Plasma samples were taken after administration. To measure tigecycline concentrations, high-performance liquid chromatography coupled with tandem mass spectrometry was used. Compartmental and non-compartmental analyses were used for pharmacokinetic analyses of mean plasma concentrations versus time. With the exception of sodium caprate, all the excipients significantly increased the area under the curve and bioavailability of tigecycline (p < 0.05). These parameters were approximately doubled by HP-β-CD, TPGS, and SDOCH, with 95% confidence intervals (95% CIs) for the difference that included only increases of 1.5-fold or higher (bioavailability: control, 1.67%; HP-β-CD, 3.24%; TPGS, 3.30%; and SDOCH, 3.24%). The increases in these parameters were smaller with DM-β-CD and TMC (DM-β-CD, 2.41%; TMC, 2.55%), and the 95% CIs ranged from close to no difference to nearly double the values in the control group. These results indicate that HP-β-CD, TPGS, and SDOCH substantially increase the area under the curve and oral bioavailability of tigecycline. They suggest that DM-β-CD and TMC may also substantially increase these parameters, but more research is needed for more precise estimates of their effects.

Development and evaluation emulgel for effective management of the imiquimod-induced psoriasis

Our main aim is in the present investigation, development and evaluation of seabuckthorn oil-based Emulgel formulation for psoriasis therapy. Anti-psoriatic activity of the SeaEmulgel was studied using Imiquimod-induced psoriasis-like inflammation model Balb/c mice and parameters such as PASI score, ear thickness, spleen to body weight index including histological staining studies, enzyme-linked immune sorbent assay (ELISA), skin compliance and safety evaluation of sea buckthorn oil was performed. The globule size and PDI of sea buckthorn oil emulsion were found to be 172.70 ± 1.73 nm and 0.117 ± 0.018, respectively. In-vivo animal studies performed on male Balb/c mice and emulgel showed a reduction in redness, scaling, inflammation in psoriasis-induced mice, which was analysed by PASI scoring, body weight, spleen weight index and ear thickness. The current investigation clearly revealed the better anti-psoriatic activity of SeaEmulgel formulation against imiquimod-induced psoriasis-like skin inflammation Balb/c mice model.

Amphotericin B Nano-Assemblies Circumvent Intrinsic Toxicity and Ensure Superior Protection in Experimental Visceral Leishmaniasis with Feeble Toxic Manifestation

In spite of its high effectiveness in the treatment of both leishmaniasis as well as a range of fungal infections, the free form of the polyene antibiotic amphotericin B (AmB) does not entertain the status of the most preferred drug of choice in clinical settings. The high intrinsic toxicity of the principal drug could be considered the main impedance in the frequent medicinal use of this otherwise very effective antimicrobial agent. Taking into consideration this fact, the pharma industry has introduced many novel dosage forms of AmB to alleviate its toxicity issues. However, the limited production, high cost, requirement for a strict cold chain, and need for parenteral administration are some of the limitations that explicitly compel professionals to look for the development of an alternate dosage form of this important drug. Considering the fact that the nano-size dimensions of drug formulation play an important role in increasing the efficacy of the core drug, we employed a green method for the development of nano-assemblies of AmB (AmB-NA). The as-synthesized AmB-NA manifests desirable pharmacokinetics in the treated animals. The possible mechanistic insight suggested that as-synthesized AmB-NA induces necrosis-mediated cell death and severe mitochondrial dysfunction in L. donovani promastigotes by triggering depolarization of mitochondrial membrane potential. In vivo studies demonstrate a noticeable decline in parasite burden in the spleen, liver, and bone marrow of the experimental BALB/c mice host. In addition to successfully suppressing the Leishmania donovani, the as-formed AmB-NA formulation also modulates the host immune system with predominant Th1 polarization, a key immune defender that facilitates the killing of the intracellular parasite.

Characterization of Boswellia rivae Engl Resin as a Potential Use for Pharmaceutical Excipient

Pharmaceutical excipients derived from natural sources like resins are nowadays meritoriously used in the formulation of drugs. Resins of natural origin have many advantages over chemically synthesized substances; they are safer, nontoxic, less expensive, biodegradable, and widely available. To our knowledge, resins from plants have been not sufficiently explored for application in pharmaceutical formulations. Thus, in the present study, a resin isolated from Boswellia rivae Engl was characterized for its potential use as a pharmaceutical excipient. Method. The resin was extracted from the oleo gum resin of Boswellia rivae Engl, which involved the removal of volatile oils, gum, and Boswellic acid contents. The dried resin powder was then characterized for its micromeritic properties, heavy metal contents, moisture content, moisture absorption power, pH, solubility, swelling property, and acute toxicity profile. Moreover, the crystal nature and the chemical functionality of the resin were evaluated by using X-ray diffraction and Fourier transform infrared spectrometry, respectively. Results. The yield of the neutral resin was 13.17%, and the powder was pale yellow and had irregular surfaces. The resin was freely soluble in organic solvents but almost insoluble in water. The moisture content of the dried extract was 2.5% while its moisture absorption capacity was 2.5%, 4%, and 5.47% at 40%, 60%, and 75% RH, respectively. Besides, the maximum swelling capacities of the resin observed were 40%, 37%, and 30% at 350C, 300C, and 250C, respectively. The bulk powder exhibited a 1.21 Hausner ratio, 36.497 angles of repose, and 17.03% Carr's index, indicating the fair flowability of the powder. Heavy metals such as zinc, chromium, and cobalt were detected at a low level while elements like copper, manganese, lead, and cadmium were absent. The X-ray diffraction study revealed that the crystallinity index of the powder was 42.7% with a crystal size of 994.5A. The Boswellia resin could be safe in mice up to 3 g/kg of their body weight. In conclusion, the physicochemical properties of the resin powder investigated reveal its potential application as pharmaceutical additives in the formulation of modified release solid dosages forms like tablets and microcapsules.

Micelles in Cancer Therapy: An Update on Preclinical and Clinical Status

BACKGROUND

In the recent years, Micelles represent a promising carrier for the treatment and diagnosis of cancer. Architecturally, micelles are self-assembled nanosized colloidal aggregates prepared from amphiphilic surfactant with a hydrophobic core and hydrophilic shell. Such a composition makes them a potential carrier for delivery of hydrophobic anticancer drugs with in their core.

METHODS

Micelles have received increasing interest as an enhanced permeability and retention (EPR) targeted drug delivery systems for cancer treatment. Micelles can be modified to contribute various attractive properties, for instance, active targeting, stimuli-responsiveness. They have also proven their ability in drug targeting to tumor tissue, enhanced drug accumulation, drug stabilization, tissue penetration, prolong circulation, in vivo biocompatibility, biodegradability and reduced side effects. Micelles have displayed a vital role in multidrug delivery for cancer therapy.

RESULTS AND DISCUSSION

The aim of the present review is to provide an overview on the status of micellar nanoformulations for anticancer agents, including their pre-clinical and clinical researches. Emphasis is placed on presenting the newer strategies to enhance the therapeutic efficacy of anticancer drug at the target site. The type of co-polymers used and methods for the preparation of micelles are also highlighted in the paper.

PharmDE: A new expert system for drug-excipient compatibility evaluation

Drug-excipient compatibility study is the essential basis for excipient selection at the pre-formulation stage. According to the pharmaceutical Quality by Design (QbD) principles, a comprehensive understanding of the ingredients' physicochemical properties and a theoretical evaluation of the interaction risk between the drugs and excipients are required for conducting rational compatibility experimental design. Currently, there is an urgent need to establish an artificial intelligence system for researchers to easily get through the problem because it is very inconvenient and hard to utilize those drug-excipient incompatibility data scattered in scientific literature. Here, we designed a knowledge-driven expert system named PharmDE for drug-excipient incompatibility risk evaluation. PharmDE firstly developed an information-rich database to store incompatibility data, covering 532 data items from 228 selected articles. Then, 60 drug-excipient interaction rules were created based on our knowledge and formulation research experiences. Finally, the expert system was developed by organically integrating the database searching and rule-based incompatibility risk prediction, which resulted in four main functionalities: basic search of incompatibility database, data matching by similarity search, drug incompatibility risk evaluation, and formulation incompatibility risk evaluation. PharmDE is expected to be a useful tool for drug-excipient compatibility study and accelerate drug formulation design. It is now freely available at https://pharmde.computpharm.org.

The biological fate of the polymer nanocarrier material monomethoxy poly(ethylene glycol)-block-poly(d,l-lactic acid) in rat

Monomethoxy poly(ethylene glycol)-block-poly(d,l-lactic acid) (PEG-PLA) is a typical amphiphilic di-block copolymer widely used as a nanoparticle carrier (nanocarrier) in drug delivery. Understanding the in vivo fate of PEG-PLA is required to evaluate its overall safety and promote the development of PEG-PLA-based nanocarrier drug delivery systems. However, acquiring such understanding is limited by the lack of a suitable analytical method for the bioassay of PEG-PLA. In this study, the pharmacokinetics, biodistribution, metabolism and excretion of PEG-PLA were investigated in rat after intravenous administration. The results show that unchanged PEG-PLA is mainly distributed to spleen, liver, and kidney before being eliminated in urine over 48 h mainly (>80%) in the form of its PEG metabolite. Our study provides a clear and comprehensive picture of the in vivo fate of PEG-PLA which we anticipate will facilitate the scientific design and safety evaluation of PEG-PLA-based nanocarrier drug delivery systems and thereby enhance their clinical development.

Three-dimensional aspects of formulation excipients in drug discovery: a critical assessment on orphan excipients, matrix effects and drug interactions

Formulation/pharmaceutical excipients play a major role in formulating drug candidates, with the objectives of ease of administration, targeted delivery and complete availability. Many excipients used in pharmaceutical formulations are orphanized in preclinical drug discovery. These orphan excipients could enhance formulatability of highly lipophilic compounds. Additionally, they are safe in preclinical species when used below the LD50 values. However, when the excipients are used in formulating compounds with diverse physico-chemical properties, they pose challenges by modulating study results through their bioanalytical matrix effects. Excipients invariably present in study samples and not in the calibration curve standards cause over-/under- estimation of exposures. Thus, the mechanism by which excipients cause matrix effects and strategies to nullify these effects needs to be revisited. Furthermore, formulation excipients cause drug interactions by moderating the pathways of drug metabolizing enzymes and drug transport proteins. Although it is not possible to get rid of excipient driven interactions, it is always advised to be aware of these interactions and apply the knowledge to draw meaningful conclusions from study results. In this review, we will comprehensively discuss a) orphan excipients that have wider applications in preclinical formulations, b) bioanalytical matrix effects and possible approaches to mitigating these effects, and c) excipient driven drug interactions and strategies to alleviate the impacts of drug interactions.

Impact of solvents on the in vitro genotoxicity of TMPTA in human HepG2 cells

Small hydrophobic chemical compounds require solvents to produce suitable solutions for toxicological studies. However, some solvents can modify the biological properties of substances and therefore their toxicity. This specific issue has been raised for PEG-400 as an anti-inflammatory and anti-oxidative compound. Recently, in the context of the REACH Regulation, PEG-400 was used to test the in vivo genotoxicity of trimethylolpropane triacrylate (TMPTA) in the comet assay. TMPTA failed to increase DNA damage whereas it induces genotoxicity in vitro in DMSO. Therefore, we questioned whether PEG-400 could modify the genotoxicity of TMPTA. The aim of this study was to determine the potential impact of PEG-400 on the in vitro genotoxicity of TMPTA, compared to DMSO. TMPTA was dissolved in either PEG-400 or DMSO, and the induction of γH2AX and Caspase-3 was analyzed in HepG2 cells. TMPTA induced γH2AX and Caspase-3 with both PEG-400 and DMSO. However, TMPTA induced effects at 4-fold lower concentrations when PEG-400 is used as the solvent compared to DMSO. While genotoxic effects are observed at much lower concentrations with PEG-400, it does not modify the in vitro genotoxicity of TMPTA. However, further in vitro studies with small hydrophobic compounds should be done to clarify the effect of PEG-400. Moreover, in vivo studies should be performed to confirm that PEG-400 remains suitable for in vivo genotoxicity tests.

Nanocrystal dispersion of DK-I-56-1, a poorly soluble pyrazoloquinolinone positive modulator of α6 GABAA receptors: Formulation approach toward improved in vivo performance

DK-I-56-1 (7‑methoxy‑2-(4‑methoxy‑d₃-phenyl)-2,5-dihydro-3H-pyrazolo[4,3-c]quinolin-3-one), a recently developed deuterated pyrazoloquinolinone, has been recognized as a lead candidate for treatment of various neuropsychiatric disorders. During preclinical investigation of poorly water-soluble compounds such as DK-I-56-1, the application of nanotechnology could be advantageous due to improved safety and possibly increased bioavailability of nanosized formulation. DK-I-56-1 nanosuspensions stabilized by polysorbate 80, alone or in combination with poloxamers 188 i.e. 407 or d-α-tocopheryl polyethylene glycol 1000 succinate, were prepared using a small-scale media milling device. With particle size 208.7-250.6 nm and polydispersity index <0.250, selected nanodiseprsions were stable for three weeks. Pharmacokinetic and biodistribution studies following intraperitoneal administration of three types of formulation in mice indicated high plasma DK-I-56-1 levels after solution (10,228.6 ± 1037.2 ngh/ml) and nanosuspension (6770.4 ± 770.7 ngh/ml) but not suspension administration (966.0 ± 58.1 ngh/ml). However, distribution of DK-I-56-1 after solution was heavily influenced by its composition, and brain availability of nanosuspension was superior to that of solution formulation. In spontaneous locomotor activity test, the expected hyperlocomotor effect was observed after nanosuspension administration, without compromising impact of the vehicle/excipients used. Therefore, nanonization of drug compound assembled with proper selection of stabilizers may seemingly contribute further thorough testing of DK-I-56-1 preclinical efficacy.

Lipid-Based Nanosystem As Intelligent Carriers for Versatile Drug Delivery Applications

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The contemporary drug discovery research shows that most of the drug candidates are highly potent, but showing poor aqueous solubility leads a variety of challenges for formulation scientists to develop a suitable formulation to improve the systemic bioavailability of such drugs. Lipid-based nanocarriers act as a major and most projecting approach overcoming the limitations which affect several physiochemical properties of drug such as the solubility, partition coefficient and bioavailability or absorption. This also fulfills a variety of product requirements and helps to overcome several limitations as decided by symptoms of the disease, various routes of administration of drug, price concern, increasing strength of product, noxious or harmful effect of drug, and dose efficacy. The lipidic nanosystem formulates aqueous drug in lipid base and is also a commercially feasible approach for the formulation of different dosage forms meant for topical or transdermal, oral, ocular, pulmonary, and parenteral delivery. This review provides a brief on lipid-based drug delivery nanocarrier and the mechanisms by which lipids and lipidic excipients improve the oral absorption of drugs with poor aqueous solubility and also provide a viewpoint on the promising applications of lipidic nanoparticulate systems.

Engineering of Long-Term Stable Transparent Nanoemulsion Using High-Gravity Rotating Packed Bed for Oral Drug Delivery

Background

Oil-in-water drug nanoemulsion forms drug delivery systems with high oral bioavailability. The conventional fabrication methods of nanoemulsion are low energy emulsification methods and high energy emulsification methods. However, both two methods are not ideal for industrial production. The problem of low energy emulsification methods is the high dosage of surfactant and co-surfactant which has potential biosecurity issues. What is more, high energy emulsification methods have some disadvantages, like the destruction of drug components, the price of equipment and the difficulties of industrial production. Hence, there have been a few commercial drug nanoemulsions so far.

Methods

In this work, we reported a novel method for the fabrication of stable and transparent drug nanoemulsion which contains hydrophilic drug rosuvastatin (ROS) calcium or hydrophobic drug silybinin (SYN) by using high-gravity rotating packed bed (RPB). The drug nanoemulsion was systematically characterized by droplet size, size distribution, stability and in vitro drug release as well as Caco-2 cells permeability.

Results

Compared with the self-emulsification method (SE), high-gravity technology could reduce 75% amount of mixed surfactants. The as-prepared nanoemulsion exhibited a very narrow droplet size distribution with a size of 13.53 ± 0.53 nm and a polydispersity index of 0.073 ± 0.018. Meanwhile, the drug nanoemulsion was physicochemically stable at 25°C and 4°C for one-year storage. Furthermore, both ROS and SYN nanoemulsion displayed higher cell permeability and in vitro dissolution than that of commercial formulations.

Conclusion

These results demonstrate that RPB can be a potential device to facilitate the industrial production of drug nanoemulsion.

Considerations for Determining Direct Versus Indirect Functional Effects of Solubilizing Excipients on Drug Transporters for Enhancing Bioavailability

Excipients used in drug formulations at clinically safe levels have been considered to be pharmacologically inert; however, numerous studies have suggested that many solubilizing agents may modulate drug transporter activities and intestinal absorption. Here, the reported interactions between various solubilizing excipients and drug transporters are evaluated to consider various potential underlying mechanisms. This forms the basis for debate in the field in regard to whether or not the effects are based on "direct" interactions or "indirect" consequences arising from the role of the excipients. For example, an increase in apparent drug solubility can give rise to saturation of transporters according to Michaelis-Menten kinetics. This is also drawing the attention of regulatory agencies as they seek to understand the role of formulation additives. The continued application of excipients as a tool in solubility enhancement is crucial in the drug development process, creating a need for additional data to verify the proposed mechanism behind these changes. A literature review is provided here with some guidance on other factors that should be considered to delineate the effects that arise from direct physiological interactions or indirect effects. The results of such studies may aid the rational design of bioavailability-enhancing formulations.

Temperature Effect on the Adsorption and Volumetric Properties of Aqueous Solutions of Kolliphor®ELP

Density, viscosity and surface tension of Kolliphor^® ELP, the nonionic surfactant aqueous solutions were measured at temperature T = 293–318 K and at 5K interval. Steady-state fluorescence measurements have been also made using pyrene as a probe. On the basis of the obtained results, a number of thermodynamic, thermo-acoustic and anharmonic parameters of the studied surfactant have been evaluated and interpreted in terms of structural effects and solute–solvent interactions. The results suggest that the molecules of studied surfactant at concentrations higher than the critical micelle concentration act as structure makers of the water structure.

Casein nanoparticles in combination with 2-hydroxypropyl-β-cyclodextrin improves the oral bioavailability of quercetin

The aim of this work was to optimize the preparative process of quercetin loaded casein nanoparticles as well as to evaluate the pharmacokinetics of this flavonoid when administered orally in Wistar rats. Nanoparticles were obtained by coacervation after the incubation of casein, 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and quercetin in an aqueous environment. Then, nanoparticles were purified and dried. The resulting nanoparticles displayed a size of 200 nm with a negative zeta potential and a payload of about 32 μg/mg. Release studies showed a zero-order kinetic, suggesting a mechanism based on erosion of the nanoparticle matrix. For the pharmacokinetic study, quercetin was orally administered to rats as a single dose of 25 mg/kg. Animals treated with quercetin-loaded casein nanoparticles displayed higher plasma levels than those observed in animals receiving the solution of the flavonoid (control). Thus, the relative oral bioavailability of quercetin when administered as casein nanoparticles (close to 37%) was found to be about 9-times higher than the oral solution of the flavonoid in a mixture of PEG 400 and water. In summary, the combination of casein and 2-hydroxypropyl-β-cyclodextrin produces nanoparticles that may be a good option to load quercetin for both nutraceutical and pharmaceutical purposes.

Polyethlyene Glycol 200 can Protect Rats against Drug-Induced Kidney Toxicity through Inhibition of the Renal Organic Anion Transporter 3

MK-7680, a cyclic nucleotide prodrug, caused significant kidney tubule injury in female rats when administered orally at 1000 mg/kg/day for 2 weeks using 10% Polysorbate 80 as vehicle. However, kidney injury was absent when MK-7680 was administered at the same dose regimen using 100% Polyethylene Glycol 200 (PEG 200) as the vehicle. Subsequent investigations revealed that MK-7680 triphosphate concentrations in kidney were much lower in rats treated with MK-7680 using PEG 200 compared to 10% Polysorbate 80 vehicle while plasma exposures of MK-7680 prodrug were similar. In vitro studies demonstrated that PEG 200 is an inhibitor of human renal uptake transporter organic anion transporter 3 (OAT3), of which MK-7680 is a substrate. Furthermore, PEG 200 and PEG 400 were found to interfere in vitro with human renal transporters OAT3, organic cation transporter (OCT) 2, multidrug resistance-associated protein (MRP) 2 and 4, and multidrug and toxin extrusion protein (MATE) 1 and 2K, but not OAT1. These results support a conclusion that PEG 200 may prevent MK-7680-induced kidney injury by inhibiting its active uptake into proximal tubular cells by OAT3. Caution should be exercised therefore when using PEGs as vehicles for toxicity assessment for compounds that are substrates of renal transporters.

Photochemically stabilized formulation of dacarbazine with reduced production of algogenic photodegradants

The present study aimed to develop a photochemically stabilized formulation of dacarbazine [5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide; DTIC] for reducing the production of algogenic photodegradant (5-diazoimidazole-4-carboxamide; Diazo-IC). Photochemical properties of DTIC were characterized by UV-visible light spectral analysis, reactive oxygen species (ROS) assay, and photostability testing. A pharmacokinetic study was conducted after intravenous administration of DTIC formulations (1 mg-DTIC/kg) to rats. DTIC exhibited strong absorption in the UVA range, and photoirradiated DTIC exhibited marked ROS generation. Thus, DTIC had high photoreactive potential. After exposure of DTIC (1 mM) to simulated sunlight (250 W/m²) for 3 min, remaining DTIC and yielded Diazo-IC were estimated to be ca. 230 μM and 600 μM, respectively. The addition of radical scavenger (1 mM), including l-ascorbic acid, l-cysteine (Cys), l-histidine, D-mannitol, l-tryptophan, or l-tyrosine, to DTIC (1 mM) could attenuate DTIC photoreactions, and in particular, the addition of Cys to DTIC brought ca. 34% and 86% inhibition of DTIC photodegradation and Diazo-IC photogeneration, respectively. There were no significant differences in the calculated pharmacokinetic parameters of DTIC between DTIC and DTIC with Cys (0.67 mg/kg). From these findings, the supplementary use of Cys would be an effective approach to improve the photostability of DTIC with less production of Diazo-IC.

In situ misemgel as a multifunctional dual-absorption platform for nasal delivery of raloxifene hydrochloride: formulation, characterization, and in vivo performance

BACKGROUND

Raloxifene hydrochloride (RLX) is approved by the US Food and Drug Administration for the treatment and prevention of osteoporosis, in addition to reducing the risk of breast cancer in postmenopausal women. RLX has the disadvantages of low aqueous solubility, extensive presystemic intestinal glucuronidation, and first-pass metabolism, resulting in a limited bio-availability of only 2%. The aim of this work was to enhance the bioavailability of RLX via the formulation of an in situ nasal matrix (misemgel) comprising micelles made of vitamin E and D-α-tocopheryl polyethylene glycol 1000 succinate and nanosized self-emulsifying systems (NSEMS).

MATERIALS AND METHODS

Optimization of the RLX-loaded NSEMS was performed using a mixture design. The formulations were characterized by particle size and then incorporated into an in situ nasal gel. Transmission electron microscopy, bovine nasal mucosa ex vivo permeation, and visualization using a fluorescence laser microscope were carried out on the RLX in situ misemgel comparing with raw RLX in situ gel. In addition, the in vivo performance was studied in rats.

RESULTS

The results revealed improved permeation parameters for RLX misemgel compared with control gel, with an enhancement factor of 2.4. In vivo studies revealed a 4.79- and 13.42-fold increased bioavailability for RLX in situ misemgel compared with control RLX in situ gel and commercially available tablets, respectively. The obtained results highlighted the efficacy of combining two different formulations to enhance drug delivery and the benefits of utilizing different possible paths for drug absorption.

CONCLUSION

The developed in situ misemgel matrix could be considered as a promising multifunctional platform for nasal delivery which works based on a dual-absorption mechanism.

Parenteral protein formulations: An overview of approved products within the European Union

The study presented is a comprehensive overview of commercial parenteral protein formulations, approved by the European Medicines Agency (EMA), 1995-2018. The objective of this overview was to analyse current trends in the design of commercial parenteral protein products and thereby support formulation scientists in the design of new formulations. The main data source was the publicly available European Public Assessment Reports (EPARs) published by the EMA for each authorised product. An analysis of the percentage of formulations in a liquid and lyophilised form was conducted. In addition, the number of products containing individual excipients, classified into functional categories is provided. Finally, the overview includes comprehensive details of product compositions obtained from EMA, US Food and Drug Administration (FDA) and product Marketing Authorisation Holder. Data analysis highlighted trends in the number of products approved, and the higher percentage of liquid parenteral protein formulations (66%) compared to lyophilised formulations (34%). This overview identifies the most commonly incorporated excipients employed as buffering agents, stabilisers/bulking agents, surfactants, preservatives and tonicifiers, including their concentration ranges of use in both liquid and lyophilised formulation approaches. Finally, antibody-based formulations were a particular focus of this overview. The relationship between parenteral routes of administration and antibody concentrations in approved products was also investigated.

Evaluation of Two Potent and Selective PET Radioligands to Image COX-1 and COX-2 in Rhesus Monkeys

This study assessed whether the newly developed PET radioligands ¹¹C-PS13 and ¹¹C-MC1 could image constitutive levels of cyclooxygenase (COX)-1 and COX-2, respectively, in rhesus monkeys. Methods: After intravenous injection of either radioligand, 24 whole-body PET scans were performed. To measure enzyme-specific uptake, scans of the 2 radioligands were also performed after administration of a nonradioactive drug preferential for either COX-1 or COX-2. Concurrent venous samples were obtained to measure parent radioligand concentrations. SUVs were calculated from 10 to 90 min. Results: ¹¹C-PS13 showed specific uptake in most organs, including spleen, gastrointestinal tract, kidneys, and brain, which was blocked by COX-1, but not COX-2, preferential inhibitors. Specific uptake of ¹¹C-MC1 was not observed in any organ except the ovaries and possibly kidneys. Conclusion: The findings suggest that ¹¹C-PS13 has adequate signal in monkeys to justify its extension to human subjects. In contrast, ¹¹C-MC1 is unlikely to show significant signal in healthy humans, though it may be able to do so in inflammatory conditions.

Pharmacokinetics of lipid-drug conjugates loaded into liposomes

Drugs that are neither lipophilic nor suitable for encapsulation via remote loading procedures are generally characterized by low entrapment efficiencies and poor retention in liposomes. One approach to circumvent this problem consists in covalently linking a lipid to the drug molecule in order to permit its insertion into the vesicle membrane. The nature of the conjugated lipid and linker, as well as the composition of the liposomal bilayer were found to have a profound impact on the pharmacokinetic properties and biodistribution of the encapsulated drugs as well as on their biological activity. This contribution reviews the past and recent developments on liposomal lipid-drug conjugates, and discusses important issues related to their stability and in vivo performance. It also provides an overview of the data that were generated during the clinical assessment of these formulations. The marketing authorization of the immunomodulating compound mifamurtide in several countries as well as the promising results obtained with the lipid prodrug of mitomycin C suggest that carefully designed liposomal formulations of lipid-drug conjugates is a valid strategy to improve a drug's pharmacokinetic profile and with that its therapeutic index and/or efficacy.

The Effect of Piperine Pro-Nano Lipospheres on Direct Intestinal Phase II Metabolism: The Raloxifene Paradigm of Enhanced Oral Bioavailability

Phase II biotransformation reactions have been gaining more attention due to their acknowledged significance in drug bioavailability, drug development, and drug-drug interactions. However, the predominant role of phase I metabolism has always overshadowed phase II metabolism, resulting in insufficient data regarding its mechanisms. In this paper, we investigate the effect of an advanced lipid based formulation on the phase II metabolism process of glucuronidation, occuring in the enterocytes monolayer. The investigated formulation is a self-emulsifying drug delivery system, termed pro-nano lipospheres, which contains the natural absorption enhancer piperine. To evaluate the effect of this formulation on direct glucuronidation we chose the model molecule raloxifene. First, glucuronidation is the main clearance pathway of this compound without involvement of preceding mechanisms. Second, raloxifene's extensive glucuronidation site is primarily at the intestine. Raloxifene's oral bioavailability was determined in a series of pharmacokinetic experiments using the freely moving rat model. In order to test the effect of the formulation on the relevant UGT enzymes reported in the clinic, we used the in vitro method of UGT-Glo Assay. Coadministration of raloxifene and piperine pro-nano lipospheres to rats resulted in a 2-fold increase in the relative oral bioavailability of raloxifene. However, coadministration of raloxifene with blank pro-nano lipospheres had no effect on its oral bioavailability. In contrast to the difference found in vivo between the two vehicles, both formulations extended an inhibitory effect on UGT enzymes in vitro. Ultimately, these findings prove the ability of the formulation to diminish intestinal direct phase II metabolism which serves as an absorption obstacle for many of today's marketed drugs. Pro-nano lipospheres is a formulation that serves as a platform for the simultaneous delivery of the absorption enhancer and a required drug. The discrepancy found between the in vivo and in vitro models demonstrates that the in vitro method may not be sensitive enough to distinguish the difference between the formulations.

Active intestinal drug absorption and the solubility-permeability interplay

The solubility-permeability interplay deals with the question: what is the concomitant effect on the drug's apparent permeability when increasing the apparent solubility with a solubility-enabling formulation? The solubility and the permeability are closely related, exhibit certain interplay between them, and ongoing research throughout the past decade shows that treating the one irrespectively of the other may be insufficient. The aim of this article is to provide an overview of the current knowledge on the solubility-permeability interplay when using solubility-enabling formulations for oral lipophilic drugs, highlighting active permeability aspects. A solubility-enabling formulation may affect the permeability in opposite directions; the passive permeability may decrease as a result of the apparent solubility increase, according to the solubility-permeability tradeoff, but at the same time, certain components of the formulation may inhibit/saturate efflux transporters (when relevant), resulting in significant apparent permeability increase. In these cases, excipients with both solubilizing and e.g. P-gp inhibitory properties may lead to concomitant increase of both the solubility and the permeability. Intelligent development of such formulation will account for the simultaneous effects of the excipients' nature/concentrations on the two arms composing the overall permeability: the passive and the active arms. Overall, thorough mechanistic understanding of the various factors involved in the solubility-permeability interplay may allow developing better solubility-enabling formulations, thereby exploiting the advantages analyzed in this article, offering oral delivery solution even for BCS class IV drugs.

Biomimetically engineered Amphotericin B nano-aggregates circumvent toxicity constraints and treat systemic fungal infection in experimental animals

Biomimetic synthesis of nanoparticles offers a convenient and bio friendly approach to fabricate complex structures with sub-nanometer precision from simple precursor components. In the present study, we have synthesized nanoparticles of Amphotericin B (AmB), a potent antifungal agent, using Aloe vera leaf extract. The synthesis of AmB nano-assemblies (AmB-NAs) was established employing spectro-photometric and electron microscopic studies, while their crystalline nature was established by X-ray diffraction. AmB-nano-formulation showed much higher stability in both phosphate buffer saline and serum and exhibit sustained release of parent drug over an extended time period. The as-synthesized AmB-NA possessed significantly less haemolysis as well as nephrotoxicity in the host at par with Ambisome®, a liposomized AmB formulation. Interestingly, the AmB-NAs were more effective in killing various fungal pathogens including Candida spp. and evoked less drug related toxic manifestations in the host as compared to free form of the drug. The data of the present study suggest that biomimetically synthesized AmB-NA circumvent toxicity issues and offer a promising approach to eliminate systemic fungal infections in Balb/C mice.

50years of oral lipid-based formulations: Provenance, progress and future perspectives

Lipid based formulations (LBF) provide well proven opportunities to enhance the oral absorption of drugs and drug candidates that sit close to, or beyond, the boundaries of Lipinski's 'rule-of-five' chemical space. Advantages in permeability, efflux and presystemic metabolism are evident; however, the primary benefit is in increases in dissolution and apparent intestinal solubility for lipophilic, poorly water soluble drugs. This review firstly details the inherent advantages of LBF, their general properties and classification, and provides a brief retrospective assessment of the development of LBF over the past fifty years. More detailed analysis of the ability of LBF to promote intestinal solubilisation, supersaturation and absorption is then provided alongside review of the methods employed to assess formulation performance. Critical review of the ability of simple dispersion and more complex in vitro digestion methods to predict formulation performance subsequently reveals marked differences in the correlative ability of in vitro tests, depending on the properties of the drug involved. Notably, for highly permeable low melting drugs e.g. fenofibrate, LBF appear to provide significant benefit in all cases, and sustained ongoing solubilisation may not be required. In other cases, and particularly for higher melting point drugs such as danazol, where re-dissolution of crystalline precipitate drug is likely to be slow, correlations with ongoing solubilisation and supersaturation are more evident. In spite of their potential benefits, one limitation to broader use of LBF is low drug solubility in the excipients employed to generate formulations. Techniques to increase drug lipophilicity and lipid solubility are therefore explored, and in particular those methods that provide for temporary enhancement including lipophilic ionic liquid and prodrug technologies. The transient nature of these lipophilicity increases enhances lipid solubility and LBF viability, but precludes enduring effects on receptor promiscuity and off target toxicity. Finally, recent efforts to generate solid LBF are briefly described as a means to circumvent the need to encapsulate in soft or hard gelatin capsules, although the latter remain popular with consumers and a proven means of LBF delivery.

The Effects of Pharmaceutical Excipients on Gastrointestinal Tract Metabolic Enzymes and Transporters-an Update

Accumulating evidence from the last decade has shown that many pharmaceutical excipients are not pharmacologically inert but instead have effects on metabolic enzymes and/or drug transporters. Hence, the absorption, distribution, metabolism, and elimination (ADME) of active pharmaceutical ingredients (APIs) may be altered due to the modulation of their metabolism and transport by excipients. The impact of excipients is a potential concern for Biopharmaceutics Classification System (BCS)-based biowaivers, particularly as the BCS-based biowaivers have been extended to class 3 drugs in certain dosage forms. The presence of different excipients or varying amounts of excipients between formulations may result in bio-inequivalence. The excipient impact may lead to significant variations in clinical outcomes as well. The aim of this paper is to review the recent findings of excipient effects on gastrointestinal (GI) absorption, focusing on their interactions with the metabolic enzymes and transporters in the GI tract. A wide range of commonly used excipients such as binders, diluents, fillers, solvents, and surfactants are discussed here. We summarized the reported effects of those excipients on GI tract phase I and phase II enzymes, uptake and efflux transporters, and relevant clinical significance. This information can enhance our understanding of excipient influence on drug absorption and is useful in designing pharmacokinetic studies and evaluating the resultant data.

Human Metabolites of Cannabidiol: A Review on Their Formation, Biological Activity, and Relevance in Therapy

Cannabidiol (CBD), the main nonpsychoactive constituent of Cannabis sativa, has shown a wide range of therapeutically promising pharmacological effects either as a sole drug or in combination with other drugs in adjunctive therapy. However, the targets involved in the therapeutic effects of CBD appear to be elusive. Furthermore, scarce information is available on the biological activity of its human metabolites which, when formed in pharmacologically relevant concentration, might contribute to or even account for the observed therapeutic effects. The present overview summarizes our current knowledge on the pharmacokinetics and metabolic fate of CBD in humans, reviews studies on the biological activity of CBD metabolites either in vitro or in vivo, and discusses relevant drug–drug interactions. To facilitate further research in the area, the reported syntheses of CBD metabolites are also catalogued.

Photochemical Mechanism of Riboflavin-Induced Degradation of Famotidine and a Suggested Pharmaceutical Strategy for Improving Photostability

The present study aimed to clarify the mechanism of photodegradation of famotidine with riboflavin (FMT/RF), and to develop a photochemically stabilized formulation of FMT/RF. Photochemical properties of RF were characterized by UV-VIS spectral analysis, reactive oxygen species (ROS) assay, and photostability testing. Pharmacokinetic study was conducted in rats after intravenous administration of FMT (1 mg/kg) formulation containing RF (0.01 mg/kg). The UV-VIS spectral pattern of RF partly overlapped with the sunlight spectrum, and ROS generation from photoirradiated RF was remarkable; thus, RF had high photoreactive potential. In the photostability testing, after irradiation (250 W/m(2)), degradation rate for FMT in FMT/RF was ca. 11-fold higher than that in FMT alone. The addition of radical scavengers to FMT/RF led to attenuated photodegradation of FMT/RF; in particular, the addition of L-ascorbic acid (vitamin C; VC) to FMT/RF showed ca. 86% inhibition of the photodegradation of FMT/RF. The pharmacokinetic study on FMT indicated that the addition of VC (1 mg/kg) to FMT/RF had no significant impact on the pharmacokinetic behavior of FMT. These findings suggest that ROS-mediated photochemical reaction would be involved in the photodegradation pathway of FMT/RF, and the complementary use of VC might be an attractive approach to improve the photostability of FMT/RF.

Effects of polyethylene glycols on intestinal efflux pump expression and activity in Caco-2 cells

The present study was planned to investigate the influence of polyethylene glycols (PEGs) on the activity and expression of P-glycoprotein (P-gp). Sub-toxic concentrations of PEGs in Caco-2 cells were determined using the MTT test assay. Then the measurement of Rhodamine-123 (Rho-123) uptake, a P-gp fluorescence substrate, in Caco-2 cells confronting PEG 400 (1% and 2% w/v), PEG 4000 (2% and 4% w/v), PEG 6000 (2% and 4% w/v), PEG 10000 (2% and 4% w/v), PEG 15000 (1% and 2% w/v), and PEG 35000 (2% and 4% w/v) overnight was taken to elucidate whether non-toxic concentrations of PEGs are able to impact P-gp activity. Furthermore, western blotting was carried out to investigate P-gp protein expression. The results showed that PEG 400 at concentrations of 1% (w/v) and 2% (w/v) and PEG 6000 at the concentration of 4% (w/v) are notably capable of blocking P-gp. Based on the obtained results it is concluded that the mentioned excipients could be used to obstruct P-gp efflux transporter in order to increase the bioavailability of co-administered substrate drug.

The effect of curcumin and its nanoformulation on adjuvant-induced arthritis in rats

Background

Rheumatoid arthritis (RA), induced by the prolonged inappropriate inflammatory responses, is one of the most prevalent of all chronic inflammatory joint diseases. Curcumin (CM), a yellow hydrophobic polyphenol derived from the herb turmeric, has various pharmacological activities against many chronic diseases and acts by inhibiting cell proliferation and metastasis and downregulating various factors, including nuclear factor kappa B, interleukin-1β and TNF-α. Given the pathogenesis of RA, we hypothesized that the drug also has antiarthritic effects. The aims of the present study included the following: 1) examining the therapeutic effect of CM administered via intravenous (iv) injection on RA and 2) formulating the drug into oil–water nanoemulsions (Ns) to overcome the low oral bioavailability of CM and achieve oral delivery of the drug.

Methods

The effect of CM administered through iv injection on adjuvant-induced arthritis in rats was studied in terms of paw swelling, weight indices of the thymus and spleen, and pathological changes in nuclear factor kappa B expression and inflammatory cytokines. Methotrexate was used as a positive control. The CM-Ns were prepared using a high-pressure homogenizing method and characterized with respect to the particle size and morphology. The stability of the CM-Ns in simulated gastrointestinal (GI) fluids and in vitro release were also investigated. A pharmacokinetic study of the CM-Ns and suspensions in which the plasma levels were determined using an high performance liquid chromatography method and the pharmacokinetic parameters were calculated based on a statistical moment theory was also performed in rats.

Results

CM administered via iv injection had a therapeutic effect on RA similar to methotrexate. CM-Ns with a diameter of approximately 150 nm were successfully prepared, and the drug was well encapsulated into the Ns without degradation in simulated GI conditions. The area under the curve (AUC) and C_max for the CM-Ns were more than threefold greater than those for the suspensions; moreover, similar decreases in the levels of TNF-α and interleukin-1β in both synovial fluid and blood serum were obtained from oral administration of CM-Ns and iv injection.

Conclusion

CM was an effective antiarthritic agent, and the present N formulation appeared to be a promising system that allowed RA therapy with CM to be converted from iv to oral administration.

Pharmacokinetics of cyclodextrins and drugs after oral and parenteral administration of drug/cyclodextrin complexes

Objectives

The objective of the present study was to shed some light on pharmacokinetics of cyclodextrins (CDs) and drugs after oral and parenteral administration of inclusion complexes.

Key findings

The complex binding constant in water can predict pharmacokinetics after parenteral administration, but it has to be considered in the context of the physiological environment, where plasma proteins compete with CDs for drug binding. Neither drug/CD nor drug/protein complexes can extravasate, but differently from proteins, CDs are readily cleared through glomerular filtration. In such intricate interrelationships, for complexes with low-to-mid binding constant, binding of drug to plasma proteins will mainly dictate the pharmacokinetics. Oppositely, for drugs showing large CD complex binding constant and low protein binding, significant decrease in distribution volume and enhanced excretion of unmetabolized drug are observed; thus, relevant changes in bioavailability can be predicted. In the case of oral administration, volume for dilution/dissolution of the complexes is relatively low and hence excess CD can hamper drug absorption from the gastrointestinal (GI) tract.

Summary

CDs are well-established multipurpose excipients for overcoming organoleptic and biopharmaceutical deficiencies of a variety of drugs. Balances between free and complexed drug in the GI tract and between drug–CD binding and drug–protein binding in plasma seem to play a relevant role in drug pharmacokinetics.

Formulation strategies to improve oral peptide delivery

Delivery of peptides by the oral route greatly appeals due to commercial, patient convenience and scientific arguments. While there are over 60 injectable peptides marketed worldwide, and many more in development, most delivery strategies do not yet adequately overcome the barriers to oral delivery. Peptides are sensitive to chemical and enzymatic degradation in the intestine, and are poorly permeable across the intestinal epithelium due to sub-optimal physicochemical properties. A successful oral peptide delivery technology should protect potent peptides from presystemic degradation and improve epithelial permeation to achieve a target oral bioavailability with acceptable intra-subject variability. This review provides a comprehensive up-to-date overview of the current status of oral peptide delivery with an emphasis on patented formulations that are yielding promising clinical data.

In vitro evaluation of the inhibitory potential of pharmaceutical excipients on human carboxylesterase 1A and 2

Two major forms of human carboxylesterase (CES), CES1A and CES2, dominate the pharmacokinetics of most prodrugs such as imidapril and irinotecan (CPT-11). Excipients, largely used as insert vehicles in formulation, have been recently reported to affect drug enzyme activity. The influence of excipients on the activity of CES remains undefined. In this study, the inhibitory effects of 25 excipients on the activities of CES1A1 and CES2 were evaluated. Imidapril and CPT-11 were used as substrates and cultured with liver microsomes in vitro. Imidapril hydrolase activities of recombinant CES1A1 and human liver microsomes (HLM) were strongly inhibited by sodium lauryl sulphate (SLS) and polyoxyl 40 hydrogenated castor oil (RH40) [Inhibition constant (Ki) = 0.04 ± 0.01 μg/ml and 0.20 ± 0.09 μg/ml for CES1A1, and 0.12 ± 0.03 μg/ml and 0.76 ± 0.33 μg/ml, respectively, for HLM]. The enzyme hydrolase activity of recombinant CES2 was substantially inhibited by Tween 20 and polyoxyl 35 castor oil (EL35) (K(i) = 0.93 ± 0.36 μg/ml and 4.4 ± 1.24 μg/ml, respectively). Thus, these results demonstrate that surfactants such as SLS, RH40, Tween 20 and EL35 may attenuate the CES activity; such inhibition should be taken into consideration during drug administration.