A Novel Antibiotic, Rhodomyrtone: Pharmacokinetic Studies in a Murine Model and Optimization and Validation of High-Performance Liquid Chromatographic Method for Plasma Analysis.

Rhodomyrtone has indisputable and undeniable potential as a new antibiotic for antibiotic-resistant Gram-positive bacteria. Therefore, the main objective of this study was to determine the pharmacokinetics profiles of orally administered rhodomyrtone in rats. A reverse-phase HPLC-UV method was developed, optimized and validated for the analysis of rhodomyrtone concentrations in rat plasma. The retention time of papaverine and rhodomyrtone was 3.928 and 5.937 min, with no interference with the excipients used. The lower limit of quantification (LLOQ) of rhodomyrtone in the plasma sample was 0.04 µg/mL, the accuracy of rhodomyrtone at the LLOQ level ranged from 93.64 to 106.36%, precision was 6.59%, 80-120% for accuracy and <20% CV for precision. The calibration curve was linear at concentrations ranging from 0.04 to 128 µg/mL with a correlation coefficient (r) value of equal to or greater than 0.999. Sprague Dawley rats received a single dose of rhodomyrtone at 50 and 100 mg/kg. Blood samples were collected from tail veins. The peak plasma concentration was observed at 2 h, and the area under the curve of rhodomyrtone at 50 mg/kg and 100 mg/kg was 3.41 ± 1.04 and 7.82 ± 1.53 µg·h/mL, respectively. The results demonstrated linear pharmacokinetics characteristics at the studied dosage range. The plasma concentration of rhodomyrtone was above the minimal inhibition concentrations of several common pathogenic bacteria of medical importance. The proposed HPLC-UV method is fast, cost-effective, reliable and reproducible, and it is proposed for the routine analysis of rhodomyrtone.

Safety and Biocompatibility of Mupirocin Nanoparticle-Loaded Hydrogel on Burn Wound in Rat Model.

Mupirocin nanoparticle-loaded hydrogel (MLH) was successfully developed. This study focused on the safety of cell lines and the biocompatibility of MLH for wound healing in rat models. MLH was assessed by an analysis of cytotoxicity and the secretion of inflammatory cytokines in cell lines. The cytocompatibility of MLH was compared with mupirocin ointment on full-thickness burn wounds in rats. The results indicated that MLH and blank hydrogel had no toxicity to human epidermal keratinocytes and human fibroblast cells. MLH inhibited lipopolysaccharide (LPS) activity in macrophage-like cells resulting in low nitric oxide production and reduced inflammatory cytokine production (interleukin (IL)-1ß) compared with a positive control (LPS only). In burn wounds, MLH and hydrogel healed the wound better than the other groups determined by wound contraction, reduced secretion, and the generation of new blood vessels, as well as promotion of hair follicle cells. Better granulation tissue proliferation, less necrosis, and a lower degree of inflammation were found in the MLH and blank hydrogel than in the mupirocin ointment. The hydrogel group reduced the macrophages (CD68) on day 14 at the edge of the wound. On day 28, T cells (CD3), B cells (CD20), and CD68+ cells were concentrated in the deeper subcutaneous tissue. Additionally, the transforming growth factor ß1 (TGF-ß1) concentration and matrix prometalloproteinase-2/tissue inhibitor of metalloproteinases-2 ratio in the MLH and hydrogel groups were less than those in the other groups. The MLH formulation was safe and effective in burn wound healing. Therefore, MLH formulations are promising candidates for further evaluation in clinical trials.

Deposition Pattern of Polydisperse Dry Powders in Andersen Cascade Impactor - Aerodynamic Assessment for Inhalation Experimentally and In Silico.

OBJECTIVES: An impactor is a standard instrument that applied for particle deposition assessment in the pharmaceutical aerosols. It provides data comparison between inhaler formulations. However, the deposition pattern in the impactor is not clearly understood. In practice monodisperse aerosols were employed to calibrate the impactor. MATERIALS AND METHODS: This study used polydisperse aerosols together with the computer simulation to track the particles in the impactor to understand the deposition pattern. Particles deposited on each stage of the Andersen cascade impactor were compared with its stage cut-off diameter using polydisperse aerosols by three particle sizing techniques. The relationship of cut-off diameter with particle size distribution was established for each stage. Also, the computational verification was used to complement the real experiments. RESULTS: Projected diameters from microscope images showed that the size of particles varied on the stage's collection plate, and the median size of each stage decreased along the lower stages from 8.53 to 0.92 µm. The median sizes measured by laser diffraction were close to the impactor's cut-off diameters. In silico data showed that the outlet mass fractions gradually changed in size towards the lower stages. CONCLUSION: Polydisperse aerosols and in silico computer fluid dynamics may compliment to standard calibration method.

Formulation Development of Albendazole-Loaded Self-Microemulsifying Chewable Tablets to Enhance Dissolution and Bioavailability.

Albendazole is an anthelmintic agent with poor solubility and absorption. We developed a chewable tablet (200 mg drug equivalent), containing a self-microemulsifying drug delivery system (SMEDDS), with oral disintegrating properties. The emulsion was developed using sesame and soybean oils along with surfactant/co-surfactants, and the tablets were prepared by wet granulation using superdisintegrants and adsorbents. Infra-red (IR) spectral studies revealed no interaction between the drug and excipients, and all physical and chemical parameters were within acceptable limits. Stability studies for the formulation indicated no significant change over time. An in vitro release study indicated 100% drug release within 30 min, and in vivo plasma concentrations indicated that the area under the curve (AUC) of albendazole in rats administered SMEDDS chewable tablets was significantly higher than in those administered commercial tablets or powder (p-value < 0.05). The systemic bioavailability of albendazole achieved through the SMEDDS tablets was 1.3 times higher than that achieved by the administration of comparable quantities of albendazole commercial tablets. This was due to the higher dissolution of albendazole SMEDDS in the chewable tablets. We conclude that the SMEDDS chewable formulation can be used to improve the dissolution and systemic availability of poorly water-soluble drugs.

Host-guest interactions between sildenafil and cyclodextrins: Spectrofluorometric study and molecular dynamic modeling.

Sildenafil (SF) was included in cyclodextrins (CD) to enhance its solubility. Spectrofluorometry was used to confirm the complexation constant (stability constant). The orientations of SF inside the ß-CDs and γ-CDs were fully illustrated. Molecular dynamics simulations were performed on two inclusion complexes (ß-CD/SF and γ-CD/SF) in the aqueous system. The polar methylpiperazine group was found to locate inside the ß-CD cavity, both in the wide and narrow side and was positioned 2°A from the center. In contrast, the methylpiperazine group did not fit well within the γ-CD cavity. Moreover, these results also confirmed hydrogen bonding that the highest number of bonding formed between the polar methylpiperazine sulfonyl structure and the hydroxyl group of ß-CD. The simulated binding free energy of the methylpiperazine-ß-CD inclusion complex (-6.01kcal/mol), featured a large contribution from electrostatic and van der Waals forces, which was the most stable complex. The association constant of ß-CD/SF (12.3) was higher than γ-CD/SF (3.3) and confirmed with in silico measurements of binding free energy. In summary, SF forms a stable complex with ß-CD.

Evidences for salbutamol metabolism by respiratory and liver cell lines.

This study aimed to investigate the enantiomeric biotransformation of salbutamol in the human respiratory and liver cells. The cells from the different cell growth cycles were treated with various concentrations of salbutamol sulfate. Salbutamol and its metabolites were analyzed using chiral liquid chromatography and mass spectrometry. There were no metabolites of salbutamol found in the extracellular medium, intracellular, and cell lysate of respiratory cell lines. The S/R ratios of salbutamol were found to be 0.99-1.10 in all cell lines, cell cycles, and salbutamol concentrations in this study. Salbutamol metabolites were found only in intracellular HepG2 cells. The S/R ratios of the salbutamol inside the liver cells were 10 times greater than the S/R ratios of the salbutamol in the liver extracellular medium (0.99-1.10). It is important to note that the S/R ratios of salbutamol in liver cell lysate enzyme were 0.99-1.10 whereas the S/R salbutamol metabolites inside the liver cell were around 1.91-2.14. Both salbutamol and sulfate conjugation metabolites were detected in MS chromatograms with an m/z of 239.2 and 317.6, respectively. Hence, the delivery of salbutamol directly to the respiratory system is a right target that can avoid first-pass metabolism.

Evaluation of Proinflammatory Cytokines and Adverse Events in Healthy Volunteers upon Inhalation of Antituberculosis Drugs.

Inhalation therapy is a promising drug delivery approach for tuberculosis treatment. However, there is always concern about the safety of the dosage form by inhalation as it may induce inflammation. Developing a new dosage form for inhalation must include tests for its safety especially for the tumor necrosis factor (TNF)-α and interleukine (IL)-1ß. The safety of four anti-tuberculosis (anti-TB) drugs administered via inhalation was assessed in healthy volunteers. Four anti-TB drugs; isoniazid, rifampicin, pyrazinamide and levofloxacin were prepared as dry powder and evaluated for uniformity of delivered dose and in vitro drug deposition. These four anti-TB dry powder formulations for inhalation met the criteria of uniformity of delivered dose and exhibited suitable size for lung delivery. Forty healthy volunteers were recruited and each was sequentially challenged with isoniazid, rifampicin, pyrazinamide and levofloxacin in different orders. Safety was monitored by measuring the pro-inflammatory cytokines in their sputum, lung function test, blood chemistry and adverse events. This study proves that all four anti-TB dry powders did not provoke inflammatory cytokines and are safe to healthy volunteers.

Factors Affecting Enhanced Permeation of Amphotericin B Across Cell Membranes and Safety of Formulation.

The aim of this study was to determine amphotericin B (AmB) permeation across lipid bilayer membranes mounted on Transwell® and to observe the phagocytosis of the AmB and the AmB-lipid formulations by alveolar macrophage (AM) cell lines using a fluorescence microscope. The lipid bilayer membranes were prepared from phospholipid and ergosterol as well as phospholipid and cholesterol in a ratio (67:33 mol%). AmB-lipid formulations were prepared from AmB incorporated with four lipid derivatives during a lyophilization process. In vitro cytotoxicity studies were carried out on kidney cells by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The levels of nitric oxide production by AMs exposed to these AmB-lipid formulations were determined by the Griess reaction. Phagocytosis of the AmB-lipid formulations was carried out using AM cells. The lipid bilayer membranes and AmB-lipid formulations were successfully prepared. In vitro cytotoxicity results showed less toxicity to kidney cells than pure AmB, and a 1,000-fold less production of nitric oxide by NR8383 cell lines was obtained when compared to lipopolysaccharide. Permeation results were two- to fivefold higher than for pure AmB in the ergosterol containing lipid bilayer and two- to fourfold higher than AmB in the cholesterol containing compositions, both of which were enough to kill the fungi according to their MICs and MFCs. AM phagocytosed the AmB-lipid formulations. We suggest that these products especially the AmB-sodium deoxycholate sulfate are potential candidates for targeting AM cells for the treatment of invasive pulmonary aspergillosis.

Computer-aided design of dry powder inhalers using computational fluid dynamics to assess performance.

Dry powder inhalers (DPIs) are gaining popularity for the delivery of drugs. A cost effective and efficient delivery device is necessary. Developing new DPIs by modifying an existing device may be the simplest way to improve the performance of the devices. The aim of this research was to produce a new DPIs using computational fluid dynamics (CFD). The new DPIs took advantages of the Cyclohaler® and the Rotahaler®. We chose a combination of the capsule chamber of the Cyclohaler® and the mouthpiece and grid of the Rotahaler®. Computer-aided design models of the devices were created and evaluated using CFD. Prototype models were created and tested with the DPI dispersion experiments. The proposed model 3 device had a high turbulence with a good degree of deagglomeration in the CFD and the experiment data. The %fine particle fraction (FPF) was around 50% at 60 L/min. The mass median aerodynamic diameter was around 2.8-4 µm. The FPF were strongly correlated to the CFD-predicted turbulence and the mechanical impaction parameters. The drug retention in the capsule was only 5-7%. In summary, a simple modification of the Cyclohaler® and Rotahaler® could produce a better performing inhaler using the CFD-assisted design.

The comparison of fluid dynamics parameters in an Andersen cascade impactor equipped with and without a preseparator.

The fluid dynamic data in Andersen cascade impactor (ACI) are still lacking. Airflows and those affected parameters can be predicted in a preseparator and Andersen cascade impactor (ACI) by computational modeling. This study developed a validated computational fluid dynamic (CFD) model of an ACI and investigated the effects of the preseparator on the CFD parameters. Validation of the computational nozzle velocity for each of the stage 0 to stage 5 of the ACI stages was found to be within a 3.56% error. The flow field indicated that the preseparator accelerated the airflow velocity at the induction tube from 1.13 to 3.71 ± 0.09 m/s and 2.40 to 8.68 ± 0.16 m/s (at 28.3 and 60 L/min of flow rate, respectively). The preseparator produced a nozzle's wall shear stress ranged from 0.08 to 0.34 Pa on a collection plate, while the ex-preseparator spread wall shear from the plate's center was in a range of 0.11 to 0.37 Pa (at 28.3 L/min of flow rate). Moreover, the nozzle velocities increased along the distance from the middle of the collection plate to the periphery. The CFD explained the airflow of the preseparator equipped model by accelerating the airflow along the inlet port to maximize the trapping of desirable particles and the generation of a smooth wall shear stress at the collection plate to reduce the particle re-entrainment. While, the ex-preseparator generated an airflow that resulted in a higher wall shear stress occurring on the lower stages.