Permeability of thermoplastic polyurethanes for aviation kerosene storage tanks

The permeability of thermoplastic polyurethanes of various grades for aviation kerosene is investigated. A model is proposed for predicting the decrease in fuel mass at different temperatures and the duration of storage in tanks. The composition of the used thermoplastic polyurethanes has a minor effect on the duration of tightness preservation, but it determines the rate of reduction of the fuel mass in the diffusion cell.

Determination of the through-plane profile of vanadium species in hydrated Nafion studied with micro X-ray absorption near-edge structure spectroscopy – proof of concept

Vanadium-ion transport through the polymer membrane results in a significant decrease in the capacity of vanadium redox flow batteries. It is assumed that five vanadium species are involved in this process. Micro X-ray absorption near-edge structure spectroscopy (micro-XANES) is a potent method to study chemical reactions during vanadium transport inside the membrane. In this work, protocols for micro-XANES measurements were developed to enable through-plane characterization of the vanadium species in Nafion 117 on beamline P06 of the PETRA III synchrotron radiation facility (DESY, Hamburg, Germany). A Kapton tube diffusion cell with a diameter of 3 mm was constructed. The tube diameter was chosen in order to accommodate laminar flow for cryogenic cooling while allowing easy handling of the cell components by hand. A vertical step size of 2.5 µm and a horizontal step size of 5 µm provided sufficient resolution to resolve the profile and good statistics after summing up horizontal rows of scan points. The beam was confined in the horizontal plane to account for the waviness of the membrane. The diffusion of vanadium ions during measurement was inhibited by the cryogenic cooling. Vanadium oxidation, e.g. by water radiolysis (water percentage in the hydrated membrane ∼23 wt%), was mitigated by the cryogenic cooling and by minimizing the dwell time per pixel to 5 ms. Thus, the photo-induced oxidation of V3+ in the focused beam could be limited to 10%. In diffusion experiments, Nafion inside the diffusion cell was exposed on one side to V3+ electrolyte and on the other side to VO2 +. The ions were allowed to diffuse across the through-plane orientation of the membrane during one of two short defrost times (200 s and 600 s). Subsequent micro-XANES measurements showed the formation of VO2+ from V3+ and VO2 + inside the water body of Nafion. This result proves the suitability of the experimental setup as a powerful tool for the determination of the profile of vanadium species in Nafion and other ionomeric membranes.

DEVELOPMENT OF METRONIDAZOLE MICROSPONGE INCORPORATED INTO CARBOMER-BASED VAGINAL GEL

Bacterial vaginosis (BV) is a vaginal infection caused by excessive bacterial growth, thus disrupting the natural balance of bacteria inside the vagina. Metronidazole becomes a drug of choice and a widely prescribed drug for the treatment of BV. However, when applied topically, metronidazole has a low vaginal residence time because of the natural washing mechanism of the vagina. This study aimed to improve the retention time of metronidazole inside the vagina and control its release profile. This study was prepared 4 formulas of gel for metronidazole microsponges with some concentration ratio of carbomer and triethanolamine. The evaluations carried out to test the efficacy of the developed formulation included organoleptic, pH measurement, spreadability, viscosity, mucoadhesive properties, permeation test using Franz diffusion cell and retention test. The results showed that the gel appearance was white, odourless and homogenous. The characteristics of all prepared gel for pH, viscosity, spreadability, and mucoadhesive ability were appropriate to the required standard for vaginal delivery. The permeation and retention test showed that F3 with the carbomer and triethanolamine concentration of 1.25%: 1.75% was able to retain and controlled the drug release locally in the vaginal mucosa. This study provides an alternative strategy in drug formulation for the treatment of BV.

THE EVALUATION OF ACTIVITY AND STABILITY OF ISOLATED BROMELAIN FROM PINEAPPLE CORES (ANANAS COMOSUS [L.] MERR) AND IN VITRO PENETRATION TEST OF NANOEMULSION TOPICAL BASE

Objective: Oral administration of bromelain as an anti-inflammation therapy still faces several challenges, such as the risk of contact with the gastric fluid and its low absorption rate. Therefore, bromelain isolated from the pineapple core will be formulated as a topical base in a nanoemulsion to increase its stability, activity, and ability to penetrate the skin. Methods: Bromelain was isolated from pineapple core using ammonium sulfate precipitation and dialysis, and then the isolated fraction was loaded into topical nanoemulsion for subsequent evaluation of its characteristics, stability, enzymatic activity, and for in vitro study of penetration using Franz diffusion cell. Results: The highest specific activity of bromelain fractions found in ammonium sulfate concentration is around 20–50%. After being dialyzed, the bromelain fraction showed an increase in specific activity 2.78-fold as compared to crude extract. The characteristics of bromelain nanoemulsion showed a globule size of 21.37±1.8 nm with a polydispersity index (pdI) 0.323±0.049, oil in water (o/w) type, and the type of rheology was plastic flow. The nanoemulsion stability base was observed, and there was no phase separation after centrifugation. Bromelain in nanoemulsion base showed a proteolytic activity of 5.00 U/ml with a protein content of 154.28 mg/l. In vitro penetration studies using Franz diffusion cell for 8 h showed isolated bromelain in nanoemulsion base has a total cumulative number value of 1386.94 μg/cm2 with penetrated velocity/flux (J) of 45.93 μg/cm2 h. Conclusion: The results showed promise for bromelain loaded into nanoemulsion as a vehicle for topically administered therapeutic enzymes.

ASSESSMENT OF PERMEABILITY BEHAVIOR OF BERBERINE CHLORIDE ACROSS GOAT INTESTINAL MEMBRANE IN PRESENCE OF NATURAL BIOPOTENTIATOR CURCUMIN

The present study investigates the influence of co-administration of different concentrations (2, 6, and 10 mg) of curcumin on goat intestinal permeability of berberine chloride (BBC) using Franz diffusion cell. Data obtained in triplicate from permeability studies were used to calculate percentage cumulative drug release (% CDR), apparent permeability (Papp), flux (J) and enhancement ratio (ER). Co-administration of 6 mg concentration of curcumin with BBC was found to be optimum to enhance the permeability of BBC up to 23.92 ± 0.78 % CDR, over control (8.49 ± 1.45 % CDR). At the optimized concentration of curcumin, permeability characteristics were improved significantly compared to control. The present study reveals the beneficial effect of co-administration of curcumin (6 mg) to promote membrane permeability of BBC which would be expected to improve its bioavailability, thereby therapeutic efficacy. The effect could be attributed to curcumin-mediated inhibition of intestinal efflux pump P-gp, acting as an absorption barrier for BBC.

Effects of Transcutol P and Precirol ATO-5 on Percutaneous Absorption of Flutamide from Emulgels

Background: Flutamide is a non-steroidal anti-androgenic agent which is not only used in treating prostate cancer but also can be effective in some disorders such as androgenic alopecia and male pattern baldness. Several serious side effects for systemic administration of flutamide can be overcome by emulgel dosage form. Absorption enhancers can promote permeation of flutamide through skin. Percutaneous absorption of Flutamide emulgels with different concentrations of Transcutol P and Precirol ATO5 was studied. Methods: Various emulgel formulations using different concentration of Transcutol P and Precirol ATO5 with 0.5 to 5 % w/w were prepared. Percutaneous absorption was tested with standard Franz Diffusion Cell equipment using full thickness rat skin. Drug concentrations in the samples were analyzed by High-Performance Liquid Chromatography (HPLC) equipped with UV-Vis detector at 305 nm. Results: The percutaneous absorption of flutamide emulgels formulated with enhancers was higher than control formulations. Enhancement ratio increased from 1.218 to 3.670 and 1.346 to3.900 for Precirol ATO5 and Transcutol P, respectively. Area under the Curve (AUC) increased by increase the enhancers’ concentration and a significant upsurge was seen in the concentration 1% for both enhancers. Conclusion: The flutamide emulgel containing 1% Transcutol P showed more appropriate percutaneous absorption through the skin compared to others.

The Development of an In Vitro Horizontal Diffusion Cell to Monitor Nasal Powder Penetration Inline

The development of in vitro investigation models could be important using sensitive and fast methods during formulation. Intranasal applied drugs (meloxicam, lamotrigine, and levodopa) avoid the gastrointestinal tract and can achieve higher bioavailability, therefore a penetration extent is a key property. In this study, the in vitro adaptability of a modified horizontal diffusion cell was tested by using these model active pharmaceutical ingredients (APIs). The special factors consisted of the volume of the chambers, the arrangement of the stirrers, the design of probe input for real-time analysis and decreased membrane area. Membranes were impregnated by isopropyl myristate and by using phosphate buffer to evaluate the effect of API hydrophilicity on the diffusion properties. The lipophilicity of the API was proportional to the penetration extent through isopropyl myristate-impregnated membranes compared with buffer-soaked membranes. After evaluating the arithmetic mean of standard relative deviations and the penetrated extent of APIs at 15 min, Metricel® could be suggested for levodopa and meloxicam, and Whatman™ for lamotrigine. The modified model is suitable for inline, real-time detection, at nasal conditions, using small volumes of phases, impregnated membrane, to monitor the diffusion of the drug and to determine its concentration in the acceptor and donor phases.

Influence of Vertical Diffusion Cell Set-Up on In Vitro Silver Sulfadiazine Drug Release from Thermo-Responsive Cellulose Hydrogel

In-vitro drug release is used to measure the release of the silver sulfadiazine (SSD) from thermo-responsive cellulose hydrogel using a vertical diffusion cell (VDC). However, selected VDC set-up used by researchers are random, and the studies are lacking in information on the challenging sink conditions during in-vitro drug release study. The objective of this study is to examine the influence of VDC set-up on the in-vitro SSD drug release from thermo-responsive cellulose hydrogel. VDC set-up including receptor medium composition, membrane type, and stirring speed were studied. The results depicted that SSD release rate increased with increasing ammonia percentage in phosphate buffer solution. On the other hand, membrane type do not influence SSD release rate. While, increasing stirring speed results in forming vortex or air bubble entrapment underneath the membrane. 0.25 v/v% ammonia receptor medium, cellulose membrane or polysulfone membrane, and 600 rpm stirring speed are the optimum VDC set-up, confirming sink condition and discriminating ability of this optimum VDC set-up. This work has successfully studied the influence of VDC set-up on in-vitro SSD drug release from thermo-responsive cellulose hydrogel, and the optimum VDC set-up was selected.