Bio-shielding <Emphasis Type="Italic">In Situ</Emphasis> Forming Gels (BSIFG) Loaded With Lipospheres for Depot Injection of Quetiapine Fumarate: <Emphasis Type="Italic">In Vitro</Emphasis> and <Emphasis Type="Italic">In Vivo</Emphasis> Evaluation

Quetiapine fumarate (QF), an anti-schizophrenic drug, suffers from rapid elimination and poor bioavailability due to extensive first-pass effect. Intramuscularly (IM) injected lipospheres were designed to enhance the drug’s bioavailability and extend its release. A central composite design was applied to optimize the liposphere preparation by a melt dispersion technique using Compritol® 888 ATO or glyceryl tristearate as lipid component and polyvinyl alcohol as surfactant. Lipospheres were evaluated for their particle size, entrapment efficiency, and in vitro release. The optimized QF lipospheres were prepared using a Compritol® 888 ATO fraction of 18.88% in the drug/lipid mixture under a stirring rate of 3979 rpm. The optimized lipospheres were loaded into a thermoresponsive in situ forming gel (TRIFG) and a liquid crystalline in situ forming gel (LCIFG) to prevent in vivo degradation by lipases. The loaded gels were re-evaluated for their in vitro release and injectability. Bioavailability of QF from liposphere suspension and bio-shielding in situ gels loaded with QF lipospheres were assessed in rabbits compared to drug suspension. Results revealed that the AUC_0–72 obtained from the liposphere-loaded TRIFG was ～3-fold higher than that obtained from the aqueous drug suspension indicating the bio-shielding effect of Poloxamer® 407 gel to inhibit the biodegradation of the lipospheres prolonging the residence of the drug in the muscle for higher absorption. Our results propose that bio-shielding in situ Poloxamer® 407 gels loaded with lipospheres is promising for the development of IM depot injection of drugs having extensive first-pass metabolism and rapid elimination.     

Lyotropic Liquid Crystalline Nanoparticles of Amphotericin B: Implication of Phytantriol and Glyceryl Monooleate on Bioavailability Enhancement

Implication of different dietary specific lipids such as phytantriol (PT) and glyceryl monooleate (GMO) on enhancing the oral bioavailability of amphotericin B (AmB) was examined. Liquid crystalline nanoparticles (LCNPs) were prepared using hydrotrope method, followed by in vitro characterization, Caco-2 cell monolayer uptake, and in vivo pharmacokinetic and toxicity evaluation. Optimized AmB-LCNPs displayed small particle size (<?210 nm) with a narrow distribution (~?0.2), sustained drug release and high gastrointestinal stability, and reduced hemolytic toxicity. PLCNPs presented slower release, i.e., ~?80% as compared to ~?90% release in case of GLCNPs after 120 h. Significantly higher uptake in Caco-2 monolayer substantiated the role of LCNPs in increasing the intestinal permeability followed by increased drug titer in plasma. Pharmacokinetic studies demonstrated potential of PT in enhancing the bioavailability (approximately sixfold) w.r.t. of its native counterpart with reduced nephrotoxicity as presented by reduced nephrotoxicity biomarkers and histology studies. These studies established usefulness of PLCNPs over GLCNPs and plain drug. It can be concluded that acid-resistant lipid, PT, can be utilized efficiently as an alternate lipid for the preparation of LCNPs to enhance bioavailability and to reduce nephrotoxicity of the drug as compared to other frequently used lipid, i.e., GMO.     

Development of Silymarin Self-Microemulsifying Drug Delivery System with Enhanced Oral Bioavailability

The objective of this work was to develop a self-microemulsifying drug delivery system (SMEDDS) for improving oral absorption of poorly water-soluble drug, silymarin. The pseudo-ternary phase diagrams were constructed using ethyl linoleate, Cremophor EL, ethyl alcohol, and normal saline to identify the efficient self-microemulsification region. The particle size and its distribution of the resultant microemulsions were determined using dynamic light scattering. The optimal formulation with the best self-microemulsifying and solubilization ability consisted of 10% (w/w) of ethyl linoleate, 30% of Cremophor EL, and 60% of ethyl alcohol. The release of silymarin from SMEDDS was significantly faster than that from the commercial silymarin preparation hard capsule (Legalon®). The bioavailability results indicated that the oral absorption of silymarin SMEDDS was enhanced about 2.2-fold compared with the hard capsule in fasted dogs. It could be concluded that SMEDDS would be a promising drug delivery system for poorly water-soluble drugs by the oral route.     

Naproxen Microparticulate Systems Prepared Using <Emphasis Type="Italic">In Situ</Emphasis> Crystallisation and Freeze-Drying Techniques

Poor drug solubility and dissolution rate remain to be one of the major problems facing pharmaceutical scientists, with approximately 40% of drugs in the industry categorised as practically insoluble or poorly water soluble. This in turn can lead to serious delivery challenges and poor bioavailability. The aim of this research was to investigate the effects of the surfactants, poloxamer 407 (P407) and caprol® PGE 860 (CAP), at various concentrations (0.1, 0.5, 1 and 3% w/v) on the enhancement of the dissolution properties of poorly water-soluble drug, naproxen, using in situ micronisation by solvent change method and freeze-drying. The extent at which freeze-drying influences the dissolution rate of naproxen microcrystals is investigated in this study by comparison with desiccant-drying. All formulations were evaluated and characterised using particle size analysis and morphology, in vitro dissolution studies, differential scanning calorimetry (DSC), and Fourier transform infra-red (FT-IR) spectroscopy. An increase in poloxamer 407 concentration in freeze-dried formulations led to enhancement of drug dissolution compared to desiccator-dried formulations, naproxen/caprol® PGE 860 formulations and untreated drug. DSC and FT-IR results show no significant chemical interactions between drug and poloxamer 407, with only very small changes to drug crystallinity. On the other hand, caprol® PGE 860 showed some interactions with drug components, alterations to the crystal lattice of naproxen, and poor dissolution profiles using both drying methods, making it a poor choice of excipient.     

Preparation and <Emphasis Type="Italic">In Vitro</Emphasis>–<Emphasis Type="Italic">In Vivo</Emphasis> Evaluation of Sustained-Release Matrix Pellets of Capsaicin to Enhance the Oral Bioavailability

Capsaicin has multiple pharmacological activities including antioxidant, anticancer, and anti-inflammatory activities. However, its clinical application is limited due to its poor aqueous solubility, gastric irritation, and low oral bioavailability. This research was aimed at preparing sustained-release matrix pellets of capsaicin to enhance its oral bioavailability. The pellets comprised of a core of solid-dispersed capsaicin mixed with microcrystalline cellulose (MCC) and hydroxypropyl cellulose (HPMC) and subsequently coating with ethyl cellulose (EC) were obtained by using the technology of extrusion/spheronization. The physicochemical properties of the pellets were evaluated through scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). Besides, the in vitro release, in vivo absorption, and in vitro–in vivo correlation were also assessed. More importantly, the relative bioavailability of the sustained-release matrix pellets was studied in fasted rabbits after oral administration using free capsaicin and solid dispersion as references. The oral bioavailability of the matrix pellets and sustained-release matrix pellets of capsaicin was improved approximately 1.98-fold and 5.34-fold, respectively, compared with the free capsaicin. A good level A IVIVC (in vitro–in vivo correlation) was established between the in vitro dissolution and the in vivo absorption of sustained-release matrix pellets. All the results affirmed the remarkable improvement in the oral bioavailability of capsaicin owing to the successful preparation of its sustained-release matrix pellets.     

Enhancement of Bioavailability and Pharmacodynamic Effects of Thymoquinone Via Nanostructured Lipid Carrier (NLC) Formulation

Thymoquinone (TQ), obtained from black cumin (Nigella sativa), is a natural product with anti-oxidant, anti-inflammatory, and hepatoprotective effects but unfortunately with poor bioavailability. Aiming to improve its poor oral bioavailability, TQ-loaded nanostructured lipid carriers (NLCs) were prepared by high-speed homogenization followed by ultrasonication and evaluated in vitro. Bioavailability and pharmacodynamic studies were also performed. The resultant NLCs showed poor physical homogeneity in Compritol 888 ATO Pluronic F127 system which consequently produced larger particle size and polydispersity index, smaller zeta potential values, and lower short-term (30 days) physical stability than other systems. Encapsulation efficiency percentage (EE%) lied between 84.6?±?5% and 96.2?±?1.6%. TQ AUC_0–t values were higher in animals treated with NLCs, with a relative bioavailability of 2.03- and 3.97-fold (for F9 and F12, respectively) higher than TQ suspension, indicating bioavailability enhancement by NLC formulation. Hepatoprotective effects of F12 showed significant (P?<?0.05) decrease in both serum alanine amino transferase and aspartate amino transferase to reach 305.0?±?24.88 and 304.7?±?23.55 U/ml, respectively, when compared with untreated toxic group. Anti-oxidant efficacy of F12 showed significant (P?<?0.05) decline of malondialdehyde and elevation of reduced glutatione. This improvement was also confirmed histopathologically.     

Development,Optimization, and Evaluation of Carvedilol-Loaded Solid Lipid Nanoparticles for Intranasal Drug Delivery

Carvedilol, a beta-adrenergic blocker, suffers from poor systemic availability (25%) due to first-pass metabolism. The aim of this work was to improve carvedilol bioavailability through developing carvedilol-loaded solid lipid nanoparticles (SLNs) for nasal administration. SLNs were prepared by emulsion/solvent evaporation method. A 2³ factorial design was employed with lipid type (Compritol or Precirol), surfactant (1 or 2% w/v poloxamer 188), and co-surfactant (0.25 or 0.5% w/v lecithin) concentrations as independent variables, while entrapment efficiency (EE%), particle size, and amount of carvedilol permeated/unit area in 24 h (Q ₂₄) were the dependent variables. Regression analysis was performed to identify the optimum formulation conditions. The in vivo behavior was evaluated in rabbits comparing the bioavailability of carvedilol after intravenous, nasal, and oral administration. The results revealed high drug EE% ranging from 68 to 87.62%. Carvedilol-loaded SLNs showed a spherical shape with an enriched core drug loading pattern having a particle size in the range of 66 to 352 nm. The developed SLNs exhibited significant high amounts of carvedilol permeated through the nasal mucosa as confirmed by confocal laser scanning microscopy. The in vivo pharmacokinetic study revealed that the absolute bioavailability of the optimized intranasal SLNs (50.63%) was significantly higher than oral carvedilol formulation (24.11%). Hence, we conclude that our developed SLNs represent a promising carrier for the nasal delivery of carvedilol.     

Oral fast-dissolving films containing lutein nanocrystals for improved bioavailability: formulation development, <Emphasis Type="Italic">in vitro</Emphasis> and <Emphasis Type="Italic">in vivo</Emphasis> evaluation

Lutein is widely used as diet supplement for prevention of age-related macular degeneration. However, the application and efficacy of lutein in food and nutritional products has been hampered due to its poor solubility and low oral bioavailability. This study aimed to develop and evaluate the formulation of oral fast-dissolving film (OFDF) containing lutein nanocrystals for enhanced bioavailability and compliance. Lutein nanocrystals were prepared by anti-solvent precipitation method and then encapsulated into the films by solvent casting method. The formulation of OFDF was optimized by Box-Behnken Design (BBD) as follows: HPMC 2.05% (w/v), PEG 400 1.03% (w/v), Cremophor EL 0.43% (w/v). The obtained films exhibited uniform thickness of 35.64 ± 1.64 μm and drug content of 0.230 ± 0.003 mg/cm² and disintegrated rapidly in 29 ± 8 s. The nanocrystal-loaded films with reconstituted particle size of 377.9 nm showed better folding endurance and faster release rate in vitro than the conventional OFDFs with raw lutein. The microscope images, thermograms, and diffractograms indicated that lutein nanocrystals were highly dispersed into the films. After administrated to SD rats, t _max was decreased from 3 h for oral solution formulation to less than 0.8 h for OFDF formulations, and C _max increased from 150 ng/mL for solution to 350 ng/mL for conventional OFDF or 830 ng/mL for nanocrystal OFDF. The AUC _0-24h of conventional or nanocrystal OFDF was 1.37 or 2.08-fold higher than that of the oral solution, respectively. These results suggested that drug nanocrystal-loaded OFDF can be applied as a promising approach for enhanced bioavailability of poor soluble drugs like lutein.     

Enhancement of the Oral Bioavailability of Felodipine Employing 8-Arm-Poly(Ethylene Glycol): <Emphasis Type="Italic">In Vivo</Emphasis>, <Emphasis Type="Italic">In Vitro</Emphasis> and <Emphasis Type="Italic">In Silico</Emphasis> Evaluation

Poor oral bioavailability is the single most important challenge in drug delivery. Prominent among the factors responsible for this is metabolic activity of the intestinal and hepatic cytochrome P450 (CYP450) enzymes. In preliminary studies, it was demonstrated that 8-arm-PEG was able to inhibit the felodipine metabolism. Therefore, this report investigated the oral bioavailability-enhancing property of 8-arm-PEG employing detailed in vitro, in vivo, and in silico evaluations. The in vitro metabolism of felodipine by cytochrome P450 3A4-expressed human liver microsomes (HLM) was optimized yielding a typical Michaelis–Menten plot through the application of Enzyme Kinetic Module software from where the enzyme kinetic parameters were determined. In vitro investigation of 8-arm-poly(ethylene glycol) against CYP3A4-catalyzed felodipine metabolism employing human liver microsomes compared closely with naringenin, a typical grapefruit flavonoid, yielding IC₅₀ values of 7.22 and 121.97 μM, respectively. The investigated potential of 8-arm-poly(ethylene glycol) in oral drug delivery yielded satisfactory in vitro drug release results. The in vivo studies of the effects of 8-arm-poly(ethylene glycol) on the oral bioavailability of felodipine as performed in the Large White pig model showed a >100% increase in plasma felodipine levels compared to controls, with no apparent effect on systemic felodipine clearance. The outcome of this research presents a novel CYP3A4 inhibitor, 8-arm-poly(ethylene glycol) for oral bioavailability enhancement.     

Preparation and Evaluation of Diosgenin Nanocrystals to Improve Oral Bioavailability

Diosgenin (DSG), a well-known steroid sapogenin derived from Dioscorea nipponica Makino and Dioscorea zingiberensis Wright, has a variety of bioactivities. However, it shows low oral bioavailability due to poor aqueous solubility and strong hydrophobicity. The present study aimed to develop DSG nanocrystals to increase the dissolution and then improve the oral bioavailability and biopharmaceutical properties of DSG. DSG nanocrystals were prepared by the media milling method using a combination of pluronic F127 and sodium dodecyl sulfate as surface stabilizers. The physicochemical properties of the optimal DSG nanocrystals were characterized using their particle size distribution, morphology, differential scanning calorimetry, powder X-ray diffraction, Fourier transform infrared spectroscopy data, and solubility and dissolution test results. Pharmacokinetic studies of the DSG coarse suspension and its nanocrystals were performed in rats. The particle size and polydispersity index of DSG nanocrystals were 229.0?±?3.7 nm and 0.163?±?0.064, respectively. DSG retained its original crystalline state during the manufacturing process, and its chemical structure was not compromised by the nanonizing process. The dissolution rate of the freeze-dried DSG nanocrystals was significantly improved in comparison with the original DSG. The pharmacokinetic studies showed that the AUC_0–72h and C _max of DSG nanocrystals increased markedly (p?<?0.01) in comparison with the DSG coarse suspension by about 2.55- and 2.01-fold, respectively. The use of optimized nanocrystals is a good and efficient strategy for oral administration of DSG due to the increased dissolution rate and oral bioavailability of DSG nanocrystals.     

<Emphasis Type="Italic">In Vitro</Emphasis>-<Emphasis Type="Italic">In Vivo</Emphasis> Evaluation of Novel Co-spray Dried Rifampicin Phospholipid Lipospheres for Oral Delivery

The objective of this study comprises of developing novel co-spray dried rifampicin phospholipid lipospheres (SDRPL) to investigate its influence on rifampicin solubility and oral bioavailability. Solid-state techniques were employed to characterize the liposphere formulation. SDRPL solubility was determined in distilled water. BACTEC 460TB System was employed to evaluate SDRPL antimycobacterial activity. The oral bioavailability of the lipospheres was evaluated in Sprague Dawley rats. Lipospheres exhibited amorphous, smooth spherical morphology with a significant increase (p?<?0.001) in solubility of SDRPL (2:1), 350.9?±?23 versus 105.1?±?12 μg/ml and SDRPL (1:1) 306.4?±?20 versus 105.1?±?12 μg/ml in comparison to rifampicin (RMP). SDRPL exhibited enhanced activity against Mycobacterium tuberculosis, H37Rv strain, with over twofolds less minimum inhibitory concentration (MIC) than the free drug. Lipospheres exhibited higher peak plasma concentration (109.92?±?25 versus 54.31?±?18 μg/ml), faster T _max (two versus four hours), and enhanced area under the curve (AUC_0–∞) (406.92?±?18 versus 147.72?±?15 μg h/L) in comparison to pure RMP. Thus, SDRPL represents a promising carrier system exhibiting enhanced antimycobacterial activity and oral bioavailability of rifampicin.     

Comparative pan genome analysis of oral <Emphasis Type="Italic">Prevotella</Emphasis> species implicated in periodontitis

Prevotella is part of the oral bacterial community implicated in periodontitis. Pan genome analyses of eight oral Prevotella species, P. dentalis, P. enoeca, P. fusca, P. melaninogenica, P. denticola, P. intermedia 17, P. intermedia 17-2 and P. sp. oral taxon 299 are presented in this study. Analysis of the Prevotella pan genome revealed features such as secretion systems, resistance to oxidative stress and clustered regularly interspaced short palindromic repeat (CRISPR)-Cas systems that enable the bacteria to adapt to the oral environment. We identified the presence of type VI secretion system (T6SS) in P. fusca and P. intermedia strains. For some VgrG and Hcp proteins which were not part of the core T6SS loci, we used gene neighborhood analysis and identified putative effector proteins and putative polyimmunity loci in P. fusca and polymorphic toxin systems in P. intermedia strains. Earlier studies have identified the presence of Por secretion system (PorSS) in P. gingivalis, P. melaninogenica and P. intermedia. We noted the presence of their homologs in six other oral Prevotella studied here. We suggest that in Prevotella, PorSS is used to secrete cysteine proteases such as interpain and C-terminal domain containing proteins with a “Por_secre_tail” domain. We identified subtype I-B CRISPR-Cas system in P. enoeca. Putative CRISPR-Cas system subtypes for 37 oral Prevotella and 30 non-oral Prevotella species were also predicted. Further, we performed a BLASTp search of the Prevotella proteins which are also conserved in the red-complex pathogens, against the human proteome to identify potential broad-spectrum drug targets. In summary, the use of a pan genome approach enabled identification of secretion systems and defense mechanisms in Prevotella that confer adaptation to the oral cavity.     

<Emphasis Type="Italic">In Vitro</Emphasis> and <Emphasis Type="Italic">Ex Vivo</Emphasis> Evaluations of Lipid Anti-Cancer Nanoformulations: Insights and Assessment of Bioavailability Enhancement

Lipid-based nanoformulations have been extensively investigated for improving oral efficacy of plethora of drugs. Chemotherapeutic agents remain a preferred option for effective management of cancer; however, most chemotherapeutic agents suffer from limitation of poor oral bioavailability that is associated with their physicochemical properties. Drug delivery via lipid-based nanosystems possesses strong rational and potential for improving oral bioavailability of such anti-cancer molecules through various mechanisms, viz. improving their gut solubilisation owing to micellization, improving mucosal permeation, improving lymphatic uptake, inhibiting intestinal metabolism and/or inhibiting P-glycoprotein efflux of molecules in the gastrointestinal tract. Various in vitro characterization techniques have been reported in literature that aid in getting insights into mechanisms of lipid-based nanodevices in improving oral efficacy of anti-cancer drugs. The review focuses on different characterization techniques that can be employed for evaluation of lipid-based nanosystems and their role in effective anti-cancer drug delivery.     

Albendazole Microcrystal Formulations Based on Chitosan and Cellulose Derivatives: Physicochemical Characterization and <Emphasis Type="Italic">In Vitro</Emphasis> Parasiticidal Activity in <Emphasis Type="Italic">Trichinella spiralis</Emphasis> Adult Worms

The oral route has notable advantages to administering dosage forms. One of the most important questions to solve is the poor solubility of most drugs which produces low bioavailability and delivery problems, a major challenge for the pharmaceutical industry. Albendazole is a benzimidazole carbamate extensively used in oral chemotherapy against intestinal parasites, due to its extended spectrum activity and low cost. Nevertheless, the main disadvantage is the poor bioavailability due to its very low solubility in water. The main objective of this study was to prepare microcrystal formulations by the bottom-up technology to increase albendazole dissolution rate, in order to enhance its antiparasitic activity. Thus, 20 novel microstructures based on chitosan, cellulose derivatives, and poloxamer as a surfactant were produced and characterized by their physicochemical properties and in vitro biological activity. To determine the significance of type and concentration of polymer, and presence or absence of surfactant in the crystals, the variables area under the curve, albendazole microcrystal solubility, and drug released (%) at 30 min were analyzed with a three-way ANOVA. This analysis indicated that the microcrystals made with hydroxyethylcellulose or chitosan appear to be the best options to optimize oral absorption of the active pharmaceutical ingredient. The in vitro evaluation of anthelmintic activity on adult forms of Trichinella spiralis identified system S10A as the most effective, of choice for testing therapeutic efficacy in vivo.     

Pharmacokinetic Evaluation of Improved Oral Bioavailability of Valsartan: Proliposomes <Emphasis Type="Italic">Versus</Emphasis> Self-Nanoemulsifying Drug Delivery System

The objective of this study was to develop proliposomes and self-nanoemulsifying drug delivery system (SNEDDS) for a poorly bioavailable drug, valsartan, and to compare their in vivo pharmacokinetics. Proliposomes were prepared by thin-film hydration method using different lipids such as soy phosphatidylcholine (SPC), hydrogenated soy phosphatidylcholine (HSPC), distearyl phosphatidylcholine (DSPC), dimyristoylphosphatidylcholine (DMPC), and dimyristoyl phosphatidylglycerol sodium (DMPG) and cholesterol in various ratios. SNEDDS formulations were prepared using varying concentrations of capmul MCM, labrafil M 2125, and Tween 80. Both proliposomes and SNEDDS were evaluated for particle size, zeta potential, in vitro drug release, in vitro permeability, and in vivo pharmacokinetics. In vitro drug release was carried out in purified water and 0.1 N HCl using USP type II dissolution apparatus. In vitro drug permeation was studied using parallel artificial membrane permeation assay (PAMPA) and everted rat intestinal permeation techniques. Among the formulations, the proliposomes with drug/DMPG/cholesterol in the ratio of 1:1:0.5 and SNEDDS with capmul MCM (16.0% w/w), labrafil M 2125 (64.0% w/w), and Tween 80 (18.0% w/w) showed the desired particle size and zeta potential. Enhanced drug release was observed with proliposomes and SNEDDS as compared to pure valsartan. Valsartan permeability across PAMPA and everted rat intestinal permeation models was significantly higher with proliposomes and SNEDDS. Following single oral administration of proliposomes and SNEDDS, a relative bioavailability of 202.36 and 196.87%, respectively, was achieved compared to pure valsartan suspension. The study results indicated that both proliposomes and SNEDDS formulations are comparable in improving the oral bioavailability of valsartan.     

Enhancement of Dissolution and Skin Permeability of Pentazocine by Proniosomes and Niosomal Gel

Proniosomes (PN) are the dry water-soluble carrier systems that may enhance the oral bioavailability, stability, and topical permeability of therapeutic agents. The low solubility and low oral bioavailability due to extensive first pass metabolism make Pentazocine as an ideal candidate for oral and topical sustained release delivery. The present study was aimed to formulate the PNs by quick slurry method that are converted to niosomes (liquid dispersion) by hydration, and subsequently formulated to semisolid niosomal gel. The PNs were found in spherical shape in the SEM and stable in the physicochemical and thermal analysis (FTIR, TGA, and XRD). The quick slurry method produced high recovery (>?80% yield) and better flow properties (θ?=?28.1–37.4°). After hydration, the niosomes exhibited desirable entrapment efficiency (44.45–76.23%), size (4.98–21.3 μm), and zeta potential (??9.81 to ??21.53 mV). The in vitro drug release (T_100%) was extended to more than three half-lives (2–4 h) and showed good fit to Fickian diffusion indicated by Korsmeyer-Peppas model (n?=?0.136–0.365 and R²?=?0.9747–0.9954). The permeation of niosomal gel was significantly enhanced across rabbit skin compared to the pure drug-derived gel. Therefore, the PNs are found promising candidates for oral as dissolution enhancement and sustained release for oral and topical delivery of pentazocine for the management of cancer pain.     

Phylogenetic relationships of Sakhalin taimen <Emphasis Type="Italic">Parahucho perryi</Emphasis> inferred from PCR-RFLP analysis of mitochondrial DNA

RFLP analysis of three amplified mtDNA fragments (Cytb/D-loop, ND1/ND2, and ND3/ND4L/ND4) was performed in the following taxa: Parahucho perryi, Hucho taimen, Brachymystax lenok, B. tumensis, Salmo salar, Salvelinus leucomaenis, and S. levanidovi. For mtDNA of P. perryi, a substantial decrease in the haplotype and nucleotide diversity was observed as a result of random genetic drift, caused by a reduction in the effective population size. Nucleotide divergence estimates between the mtDNA haplotypes were determined. Sakhalin taimen P. perryi was found to be approximately equally diverged from S. salar and from the charrs of the genus Salvelinus, by 11.0 and 10.0%, respectively. The divergence between P. perryi and H. taimen constituted 14.6%, between P. perryi and lenoks of the genus Brachymystax, 14.2%, and between H. taimen and Brachymystax, 7.7%. The analysis of possible phylogenetic relationships of the mtDNA from P. perryi among the group of taxa examined confirmed validity of the genus Parahucho. Phylogenetic reconstructions performed showed that robustness of the trees constructed for the complex of phylogenetically informative characters over three mtDNA fragments was considerably higher than that of the trees constructed for individual genes.     

Coamorphous Loratadine-Citric Acid System with Enhanced Physical Stability and Bioavailability

Coamorphous systems using citric acid as a small molecular excipient were studied for improving physical stability and bioavailability of loratadine, a BCS class II drug with low water solubility and high permeability. Coamorphous loratadine-citric acid systems were prepared by solvent evaporation technique and characterized by differential scanning calorimetry, X-ray powder diffraction, and Fourier transform infrared spectroscopy. Solid-state analysis proofed that coamorphous loratadine-citric acid system (1:1) was amorphous and homogeneous, had a higher T _g over amorphous loratadine, and the intermolecular hydrogen bond interactions between loratadine and citric acid exist. The solubility and dissolution of coamorphous loratadine-citric acid system (1:1) were found to be significantly greater than those of crystalline and amorphous form. The pharmacokinetic study in rats proved that coamorphous loratadine-citric acid system (1:1) could significantly improve absorption and bioavailability of loratadine. Coamorphous loratadine-citric acid system (1:1) showed excellently physical stability over a period of 3 months at 25°C under 0% RH and 25°C under 60% RH conditions. The improved stability of coamorphous loratadine-citric acid system (1:1) could be related to an elevated T _g over amorphous form and the intermolecular hydrogen bond interactions between loratadine and citric acid. These studies demonstrate that the developed coamorphous loratadine-citric acid system might be a promising oral formulation for improving solubility and bioavailability of loratadine.     

<Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>-mediated transformation: an efficient tool for targeted gene disruption in <Emphasis Type="Italic">Talaromyces marneffei</Emphasis>

Talaromyces marneffei causes life-threatening infections in immunocompromised hosts. An efficient tool for genetic manipulation of T. marneffei will allow for increased understanding of this thermally dimorphic fungus. Agrobacterium tumefaciens-mediated transformation (ATMT) was optimized for targeted gene disruption in T. marneffei using the plasmid pDHt/acuD::pyrG. Molecular analyses of transformants were performed by PCR, Southern blot and semi-quantitative RT-PCR. A. tumefaciens strain EHA105 was more efficient at transformation than strain AGL-1 in ATMT via solid co-cultivation. An A. tumefaciens:T. marneffei ratio of 1000:1 in an ATMT liquid co-cultivation led to a relatively high transformation efficiency of 90 transformants per 10⁶ yeast cells. Using ATMT-mediated knockout mutagenesis, we successfully deleted the acuD gene in T. marneffei. PCR and Southern blot analysis confirmed that acuD was disrupted and that the foreign pyrG gene was integrated into T. marneffei. Semi-quantitative RT-PCR analysis further confirmed that pyrG was expressed normally. These results suggest that ATMT can be a potential platform for targeted gene disruption in T. marneffei and that liquid co-cultivation may provide new opportunities to develop clinical treatments.