Absorption Window Research Articles

Improved gastric residence time of famotidine by raft-forming drug delivery system using DOE.

This study investigated the raft-forming suspension of famotidine as an anti-reflux formulation to improve the oral bioavailability of narrow absorption window drugs by enhancing gastric residence time (GRT) and preventing gastro-esophageal reflux disease (GERD). Various combinations of raft-forming agents, such as Tragacanth gum (TG), guar gum (GG), and xanthan gum (XG), were evaluated alongside sodium alginate (SA) to develop an effective raft. Preformulation studies and preliminary screening were conducted to identify the most suitable raft-forming agent, and GG was chosen due to its mucilaginous properties. The formulation was optimized using a 32 full factorial design, with the quantities of GG and SA as independent factors and apparent viscosity and in-vitro drug release (%) as dependent factors. The in vivo floating behavior study was performed for optimized and stabilized formulation. Among the tested batches, F6 was selected as the optimized formulation. It exhibited desirable characteristics such as adequate raft weight for extended floating in gastric fluid, improved apparent viscosity, and a significant percentage of drug release at 12h. A mathematical model was applied to the in-vitro data to gain insights into the drug release mechanism of the formulation. The stability of the suspension was assessed under accelerated conditions, and it demonstrated satisfactory stability. The formulation remains floating in the Rabbit stomach for more than 12h. It concludes that the developed formulation has enhanced bioavailability in the combination of GG and SA. The floating layer of the raft prevents acid reflux, and the famotidine is retained for an extended period of time in the gastric region, preventing excess acid secretion. The developed formulations are effective for stomach ulcers and GERD, with the effect of reducing acid secretion by H2 receptor antagonists.

Extending the absorption of Cs2AgBiCl6 double perovskite to the near infra-red region by copper doping

In this study, we establish the synthesis of Cu doped Cs2AgBiCl6 lead-free double perovskite using three different methods. Cu doping results in extending the absorption window of high bandgap Cs2AgBiCl6 double perovskite to NIR region.

Gastro Retentive Drug Delivery System: Latest Approach towards Novel Drug Delivery

Various efforts have been undertaken to enhance the bioavailability and clinical performance of oral drug formulations. In pursuit of improving the therapeutic effectiveness of medications that are susceptible to degradation in alkaline pH environments, possess a limited window for absorption within the stomach, and readily dissolve under acidic conditions, a diverse range of gastro-retentive drug delivery systems (GRDDS) have been innovatively designed and developed. As a result, the stomach’s physiological state and the various factors that influence GRDDS will be discussed. As a rule, this survey will enlighten and coordinate enumerating scientists in arranging, plan, and planning the GRDDS.

Development of a multi-component gastroretentive expandable drug delivery system (GREDDS) for personalized administration of metformin

ABSTRACT Objectives Efficacy and compliance of type II diabetes treatment would greatly benefit from dosage forms providing controlled release of metformin in the upper gastrointestinal tract. In this respect, the feasibility of a new system ensuring stomach-retention and personalized release of this drug at its absorption window for multiple days was investigated. Methods The system proposed comprised of a drug-containing core and a viscoelastic umbrella-like skeleton, which were manufactured by melt-casting and 3D printing. Prototypes, alone or upon assembly and insertion into commercially-available capsules, were characterized for key parameters: thermo-mechanical properties, accelerated stability, degradation, drug release, deployment performance, and resistance to simulated gastric contractions. Results Each part of the system was successfully manufactured using purposely-selected materials and the performance of final prototypes matched the desired one. This included: i) easy folding of the skeleton against the core in the collapsed administered shape, ii) rapid recovery of the cumbersome configuration at the target site, even upon storage, and iii) prolonged release of metformin. Conclusions Composition, geometry, and performance of the system developed in this work were deemed acceptable for stomach-retention and prolonged as well as customizable release of metformin in its absorption window, laying promising bases for further development steps.

Single crystals and optical ceramics based on solid solutions of AgCl – AgBr – AgI system

The development of infrared (IR) and terahertz (THz) optical materials is work, that is connected with prospective applications in wide-spectral systems, medicine, IR and THz techniques. This work is focused on the development of new optical materials based on silver halides in the AgCl – AgBr – AgI system, selection of technological modes, preparation of single crystals and optical ceramics and investigation of their optical properties. The phase diagram of the AgCl – AgI system was refined, and a new phase diagram of AgCl – AgBr0.7I0.3 was investigated and constructed. In both diagrams, homogeneity and heterogeneity regions were found. In the AgCl – AgI diagram, the homogeneity region covers the concentration range from 0 to 7 mol. % AgI in AgCl, and the heterogeneity region from 7 to 98 mol. % AgI in AgCl. The phase diagram of AgCl – AgBr0.7I0.3 shows two regions of homogeneity in the concentration ranges of 0–49 and 78–100 mol. % AgBr0.7I0.3 in AgCl and one heterogeneous region from 47 to 87 mol. % AgBr0.7I0.3 in AgCl. In both systems in the regions of homogeneity it is possible to grow single crystals of the cubic NaCl crystal structure, space group Fm3m. For compositions of heterogeneous regions, it is possible to synthesize two-phase optical ceramics based on the cubic phase Fm3m and the hexagonal β-modification of AgI of wurtzite type (P63mc). The results of studies of phase diagrams of AgCl – AgI and AgCl – AgBr0.7I0.3 allowed us to determine the concentration ranges in the quasi three-component isothermal section of the AgCl – AgBr – AgI system. The obtained results allowed us to determine the compositions and select optimal technological modes, according to which single crystals of AgCl0.85Br0.10I0.05, AgCl0.72Br0.19I0.09, AgCl0.58Br0.29I0.13, AgCl0.97I0.03 and AgCl0.94I0.06 compositions were grown and optical ceramics of AgCl0.14Br0.60I0.26 composition were synthesized. The structure of the materials was determined by SEM analysis. The studied transmission ranges showed that single crystals and optical ceramics transmit radiation in the range from 0.48 to 41.7 μm and more with a maximum transparency level of up to 83 %. There are no absorption windows in the transmission spectra of the materials, which allows the developed optical materials to be used in the specified spectral ranges as transmission optics.

Preparation and evaluation of floating drug delivery system (fdds) containing an antiviral drug

Acyclovir, an antiviral drug has low oral bioavailability of about 15-30%. It shows more absorption in the upper gastro intestinal tract. The main objective is to evaluate the potential of floating alginate beads as a drug carrier for acyclovir to prolong gastric residence time of drug in its absorption window. Floating beads were prepared from sodium alginate solution containing CaCO3 as gas-forming agent using Ionotropic gelation method. To overcome the limitation of drug leaching during preparation and to have improved sustained release characteristics, alginate beads were prepared with the addition of polymers like Hydroxy propyl methyl cellulose (HPMC K4M), Eudragit RL 100 and Xanthan gum. Beads were also prepared by using Pectin (polyelectrolyte) containing cross linking solution. The compatibility of drug with the polymer was confirmed through the FT-IR studies. The prepared beads were evaluated for percentage drug loading, entrapment efficiency, surface morphology and in vitro release characteristics to know the effect of addition of these polymers to alginate solution and the addition of Pectin to cross linking solution. Pectin treated beads prepared with Xanthan gum & Pectin not only showed improved percentage drug loading but also exhibited sustained drug release in the pH 1.2. So these floating alginate beads may act as a promising carrier for acyclovir to improve its oral bioavailability.

Formulation and Evaluation of Azithromycin Dihydrate Based In situ Gel as Floating Drug Delivery System

Floating Drug Delivery Systems have been used to overcome some of the problems like low oral absorption of drugs with narrow absorption window as it has an advantage of sustained release of drugs over a prolonged period of time. In-situ gels are the novel approach in the context of floating drug delivery systems. The aim of this present study was to develop an oral stomach specific floating in-situ gel of Azithromycin dihydrate. In-situ gelling system was prepared by dissolving different concentrations of polymers like sodium alginate, xanthan gum in the de-ionized water already prepared with sodium citrate at 60°C to 90°C. After the heating with continuous stirring the formulation was cooled below the temperature of 40°C with the addition of certain amount of drug and calcium carbonate which acts as gas generating agent. All the formulations showed pH in the range of 6.1 to 6.7, drug content was found to be in the range of 97.29% to 99.27%. Floating lag time was less than 1 minute for all the formulations and the duration of floatation was more than 24 hours for the combination of polymers. Appearance and measurement of water uptake by the gel was also good. Stability studies were also done and was found to be at normal phase at different temperatures and at interval of times. Although, F9 showed the maximum properties of an in-situ gel with increased gastric retention time with low slowly release of the drug. Drug release was found to be decreasing as the concentration of polymer increases. However, it was concluded that the in-situ gelling system of Azithromycin dihydrate could be prepared in various concentrations of different polymers and the combination of polymers to increase the patient compliance and reduction in the frequency of dosing of the drug with the increased gastric residence time for the drug in the stomach.

Numerical analysis of the Brewster-electrical duo-effect for multi-resonance tuning in THz absorber

The excitation and tuning of multiple resonances with narrow spectral width based on Brewster's effect is possible in an ultrathin dual-band terahertz absorber. The angular variation establishes a monotonic relation with the frequency of some generated resonances offering tunability. Moreover, burying a graphene ring resonator beneath the metallic ring splits the resonance for providing the triple narrow absorption windows. The electrical modulation offers the feature of independent tunability in the generated third absorption band. Thus, the frequency ratio of the upper to lower spectral absorption peak can be modulated by the electrically tunable Fermi energy of graphene. Engraving the graphene resonator also enhances the incident angle based tunability by affecting a greater number of Brewster generated resonance peaks. The narrow line shape of the triple band absorption can enable refractive index sensing and the detection of extraneous elements in localized analyte samples. The detection of imidacloprid pesticide in wheat flour is performed by the implemented sensor. The numerical analysis is done for the design and analysis of the absorber structures to report the above facts.

Development and assessment of gastro retentive floating tablets of celiprolol using natural polymers

Gastro retentive floating tablets are a promising drug delivery system for improving the bioavailability and therapeutic efficacy of orally administered drugs, particularly those with a narrow absorption window in the gastrointestinal tract. In this study, we aimed to develop and evaluate gastro retentive floating tablets of Celiprolol using natural polymers. The tablets were formulated by incorporating a combination of natural polymers, including hydroxypropyl methylcellulose (HPMC) and sodium alginate, to achieve buoyancy and sustained drug release. Various formulation parameters, such as polymer concentration, drug-to-polymer ratio, and effervescent agents, were optimized to attain desired tablet characteristics. The prepared tablets were evaluated for their physical characteristics, floating behavior, drug release profile, and drug stability. The optimized formulation demonstrated excellent floating properties, with a floating lag time of less than 60 seconds and a floating duration of more than 12 hours. In vitro drug release studies revealed sustained release of Celiprolol from the tablets over a period of 12 hours. The drug release kinetics followed the Higuchi model, suggesting diffusion as the predominant mechanism. Stability studies indicated that the floating tablets maintained their physical and drug release characteristics over a period of six months under accelerated storage conditions. Overall, the developed gastro retentive floating tablets of Celiprolol using natural polymers showed promising characteristics in terms of floating behavior, sustained drug release, and stability. This formulation has the potential to improve the therapeutic outcomes of Celiprolol by enhancing its bioavailability and ensuring prolonged drug exposure in the gastrointestinal tract. Further in vivo studies are warranted to validate the efficacy and pharmacokinetic profile of these tablets for potential clinical applications in the treatment of hypertension and other cardiovascular condition.

Facts and Features of Gastroretentive Drug Delivery System

Oral drug delivery has gained a lot of popularity because of patient compliance and the simplicity of administration. It only provides a small number of benefits for medications with poor bioavailability because of inadequate digestion and absorption in the latter stages of the GI tract. In this scenario, GRDDS have emerged as a preferred choice for drug administration with unique qualities such as a narrow absorption window, avoiding metabolism, instability in high alkaline pH, and improved solubility in low pH. In this present review, we discuss the Merits and demerits, the physiology of the stomach, and factors affecting the grdds. Various gastrointestinal technologies, including floating, non-floating, expandable, superporous hydrogel; Bioadhesive, magnetic, and raft system, as well as their applications, is outlined. In addition, potential future developments on this technology to minimise stomach emptying rate in both fasting and fed stages are highlighted. In the end, this review might assist formulation scientists and researchers in designing the GRDDS.

Unleashing the power of solar light: WO3 nanorods decorated onto BiVO4 dendrites for tetracycline detoxification and water splitting.

The coupling of different oxide materials in a nanohybrid enables the customization of their optical and charge transport properties, leading to improved interfacial charge segregation and migration. In this study, BiVO4/WO3 (BVW), a sunlight-driven photocatalyst with distinct mole ratios was synthesized via a facile hydrothermal approach. The resultant catalyst exhibits a nanorods shape morphology decorated onto dendrite-like matrix and is studied for photocatalytic elimination of tetracycline (TC) and photoelectrocatalytic (PEC) H2 production. The effect of illumination time, solution pH, photocatalyst concentration, and mole ratios of BiVO4 to WO3 on the photocatalytic abatement of TC were tested sequentially as effective operating factors. Under optimal condition, 3:1 BiVO4:WO3 (31BVW) nanohybrid demonstrated a maximum degradation efficacy of 96.2% (rate constant ~0.0241 min-1), which is much better than its individual components and commercial TiO2-P25 (50.9%). The resultant by-products of TC decomposition were analyzed using GC-MS to explain the degradation mechanism. Moreover, as a photoanode, 31BVW showed a high photocurrent density of 0.64 mA/cm2 at 1.23 V vs RHE and a steady photocurrent for ~6 h under chronoamperometry study at1.23 V vs RHE. However, bare BiVO4 and WO3 exhibited the photocurrent density of 0.001 mA/cm2, and 0.015 mA/cm2, respectively at 1.23 V vs RHE. The Mott-Schottky analysis of 31BVW confirms their n-type behavior, with a calculated flat band potential of -0.067 V. The hydrogen production rate was theoretically calculated as 4.56 mmolcm-2 s-1 from chronoamperometric measurements. The photocatalyst's efficacy in TC degradation was further established via its reusability upto 7 cycles. Post degradation characterization of catalyst confirms its stability in lieu of practical usage. Comparative studies with existing literature revealed the superiority of reported photocatalysts in both applications. Overall, the binary BVW photocatalyst shows great potential for removing detrimental contaminants as well as H2 production via PEC water splitting due to efficient charge separation, reduced recombination, high surface area, and widen absorption window of the nanohybrid.

Model-based optimization of controlled release formulation of levodopa for Parkinson’s disease

Levodopa is currently the standard of care treatment for Parkinson’s disease, but chronic therapy has been linked to motor complications. Designing a controlled release formulation (CRF) that maintains sustained and constant blood concentrations may reduce these complications. Still, it is challenging due to levodopa’s pharmacokinetic properties and the notion that it is absorbed only in the upper small intestine (i.e., exhibits an “absorption window”). We created and validated a physiologically based mathematical model to aid the development of such a formulation. Analysis of experimental results using the model revealed that levodopa is well absorbed throughout the entire small intestine (i.e., no “absorption window”) and that levodopa in the stomach causes fluctuations during the first 3 h after administration. Based on these insights, we developed guidelines for an improved CRF for various stages of Parkinson’s disease. Such a formulation is expected to produce steady concentrations and prolong therapeutic duration compared to a common CRF with a smaller dose per day and a lower overall dose of levodopa, thereby improving patient compliance with the dosage regime.

Artificial neural network-based inverse design of metasurface absorber with tunable absorption window

Although the development of graphene broadband terahertz (THz) absorbers is relatively mature, studies focusing on modulating the absorption window remain limited. Existing research has mainly concentrated on achieving absorption window switching via the phase transition of materials like vanadium dioxide (VO2). However, this method typically allows for switching within two specific windows, lacking the capacity for arbitrary and flexible regulation. This study introduces a novel approach involving a bilayer graphene metasurface absorber (BGMA) to address this limitation, which allows arbitrary manipulation of the absorption windows. To facilitate rapid and accurate selection of the structural parameters, an artificial neural network (ANN)-based inverse design method is employed, which achieves a tunable absorption bandwidth of 6.70 THz with an error amount to 0.59%. Through in-depth mechanistic analyses, it is demonstrated that the BGMA can achieve tunable absorption between a low-frequency broadband absorption (L-FBA) mode and a high-frequency broadband absorption (H-FBA) mode. This tunability arises from the transition between graphene localized surface plasmon resonance and graphene surface plasmon resonance. Overall, the outcomes of this study underscore the remarkable tunable performance of the BGMA achieved through ANN-based inverse design. This innovation holds significant promise for applications in security detection, and object stealth.

Controlling optical bistability, multistability and all-optical switching through multi-photon excitation process

We present a theoretical study on optical bistability (OB), optical multistability (OM) and tunable all-optical switching in a four-level cascade type atomic system. The density matrix formalism is used to find out the response of the probe laser field. We explore OB and OM under unidirectional optical ring cavity configuration. A comparison between the effects of electromagnetically induced transparency and electromagnetically induced absorption windows on OB is presented. The threshold of OB and the hysteresis width can be tuned effectively by adjusting the applied coherent fields. A transition from OB to OM and vice-versa can be easily achieved by tuning the field parameters and the atomic cooperation parameter. Dynamic control of the probe laser propagating through the medium has been investigated. We also demonstrate conversion of a continuous wave input probe field into output switched pulse. The ON/OFF time of the switched probe pulse can also be controlled by tuning the field parameters.

Effects of greenhouse gases on Earth, Venus, and Mars: Beyond the one-blanket model

I present a discussion of the effect of increasing carbon dioxide on planetary climate, at a level suitable for insertion as a module into an upper-level Physics course. The treatment includes two key ingredients that are often missing from more elementary discussions, yet are amenable to analytic methods: First, that convection implies a dependence of surface temperature on the height of the outermost infrared-thick layer; and second, that increasing the level of CO2 closes spectral windows of absorption. These themes are applicable not only to an industrializing Earth but also to our neighboring planets.

Optical materials for IR fiber optics based on solid solutions of AgCl0.25Br0.75 – TlCl0.74Br0.26, AgCl0.25Br0.75 – TlBr0.46I0.54 systems

The development of optical materials, that are transparent from the visible to the far IR without absorption windows, including fiber optics materials, continues to be an urgent scientific problem, which is associated with high prospects for their application in wide-spectrum systems, IR and THz technology. This article is devoted to the development of materials based on the AgCl0.25Br0.75 – TlCl0.74Br0.26 and AgCl0.25Br0.75 – TlBr0.46I0.54 systems from constructing phase diagrams to synthesis of single crystals and optical ceramics and their transmission properties investigation. According to the results of studying the phase diagram of the AgCl0.25Br0.75 – TlCl0.74Br0.26 system, homogeneity regions of 0–7 mol. % and 95–100 mol. % TlCl0.74Br0.26 in AgCl0.25Br0.75, in which there are single-phase solid solutions with the structure Fm3m and Pm3 m, respectively, were obtained. In this diagram, regions of heterogeneity with a composition of 7–79 mol. % and 79–95 mol. % TlCl0.74Br0.26 in AgCl0.25Br0.75 and a mixture of two phases in the first region Fm3m and R-3, and in the second region Pm3 m and R-3 were found. Within the AgCl0.25Br0.75 – TlBr0.46I0.54 system's phase diagram, homogeneity regions with compositions of 0–15 mol. % and 92–100 mol. % TlBr0.46I0.54 in AgCl0.25Br0.75 and similar structures Fm3m and Pm3 m, respectively, were determined. This system also contains regions of heterogeneity with compositions of 15–36 mol. %. and 69–92 mol. % TlBr0.46I0.54 in AgCl0.25Br0.75 with phase composition Fm3m and R-3, and Pm3 m and R-3. In each system, compositions were selected from the homogeneity and heterogeneity regions, and samples of single crystals and two-phase ceramics were synthesized. For the AgCl0.25Br0.75 – TlCl0.74Br0.26 system, a single crystal with a composition of 3 mol. % TlCl0.74Br0.26 in AgCl0.25Br0.75 and two-phase ceramics of 7, 31, 86, 92 mol. % TlCl0.74Br0.26 in AgCl0.25Br0.75 were obtained. Single crystals 3, 6, 9, 92 mol. % TlBr0.46I0.54 in AgCl0.25Br0.75 and ceramics 32, 76 mol. % TlBr0.46I0.54 in AgCl0.25Br0.75 were synthesized in AgCl0.25Br0.75 – TlBr0.46I0.54 system. The samples are 35 ± 5 mm high and 10 ± 0.1 mm in diameter, and their color varies from yellow to orange depending on the composition. The transmittance ranges of all synthesized samples were investigated. The study was carried out on polycrystalline plates with a diameter of 15 ± 5 mm, thickness of 400 ± 5 μm, and surface roughness Ra = 0.2 μm. The crystallite size of the alloying phase R-3 in the optical ceramics was less than 100 nm. For AgCl0.25Br0.75 – TlCl0.74Br0.26 system materials, the transmission spectra covered the region from 0.4 to 55.0 μm. Materials based on the AgCl0.25Br0.75 – TlBr0.46I0.54 system showed transmission in the wavelength range of 0.49–60.0 μm. All materials are transparent in the wide region without absorption windows with a transparency level up to 79%. Thus, new optical materials based on the AgCl0.25Br0.75 – TlCl0.74Br0.26 and AgCl0.25Br0.75 – TlBr0.46I0.54 systems have been developed, which have a wide transmission range from the visible to the IR. This opens broad prospects for their use as an optical material for wide-spectrum devices, as well as IR fiber optics.

Sub-Bandgap Sensitization of Perovskite Semiconductors via Colloidal Quantum Dots Incorporation.

By taking advantage of the outstanding intrinsic optoelectronic properties of perovskite-based photovoltaic materials, together with the strong near-infrared (NIR) absorption and electronic confinement in PbS quantum dots (QDs), sub-bandgap photocurrent generation is possible, opening the way for solar cell efficiencies surpassing the classical limits. The present study shows an effective methodology for the inclusion of high densities of colloidal PbS QDs in a MAPbI3 (methylammonium lead iodide) perovskite matrix as a means to enhance the spectral window of photon absorption of the perovskite host film and allow photocurrent production below its bandgap. The QDs were introduced in the perovskite matrix in different sizes and concentrations to study the formation of quantum-confined levels within the host bandgap and the potential formation of a delocalized intermediate mini-band (IB). Pronounced sub-bandgap (in NIR) absorption was optically confirmed with the introduction of QDs in the perovskite. The consequent photocurrent generation was demonstrated via photoconductivity measurements, which indicated IB establishment in the films. Despite verifying the reduced crystallinity of the MAPbI3 matrix with a higher concentration and size of the embedded QDs, the nanostructured films showed pronounced enhancement (above 10-fold) in NIR absorption and consequent photocurrent generation at photon energies below the perovskite bandgap.

Fabrication of Novel Floating 3D-Printed Devices with Adjustable Releasing Channels for Controlled Release

Gastro-retentive drug delivery systems (GRDDS) have been used to improve the therapeutic efficacy of drugs with narrow absorption windows, unstable in alkaline pH, soluble in acidic conditions, and active locally in the stomach. This study aimed to produce a novel floating three-dimensional (3D)-printed device (F3D) from polylactic acid filaments using a fused deposition modeling 3D printer. There were two parts of F3D: a cap with an air chamber for floating property and a body with 6 channels for controlled release. The device was designed to have adjustable channels for the releasing control and gastric retention of Bromhexine, carvedilol, and theophylline. The releasing channels could be adjusted by rotating the base to open or close the number of releasing channels as 3 levels (2, 4, and 6 channels). Morphology, weight variation, ex vivo floating time, and drug release characteristics were examined. The F3D had a smooth texture with a narrow SD value of weight variation and actual size, suggesting that the F3D had high accuracy and consistent fabrication using 3D printing technology. All tablets incorporated F3D was able to float for at least 24 h. Decreasing the number of channels on the devices led to the sustained release of drugs following 2> 4> 6 channels. Hence, F3D could be useful in controlling drug release for various commercial tablets. Keywords: 3D-printed device, Floating device, Fused deposition modeling, Gastroretentive drug delivery systems, controlled release dosage form

A Tunable Frequency Selective Rasorber with Broad Passband and Low Transmission Loss at X-Band.

In this paper, we propose a dual-mode frequency selective rasorber (FSR) with tunable transmission and absorption windows at the X-band, which shows a broad passband in each transmission window. The proposed tunable FSR consists of a lossy absorption layer, a lossless transmission layer, and an air gap between them. The top frequency selective surface (FSS) layer is a cross-shaped meandering line with resistors and varactors for tunable absorption, and the bottom layer is a cross-shaped gap with varactors to achieve tunable bandpass. The equivalent circuit model (ECM) is investigated, and the 3D full wave simulation is performed. The results are based on simulations, and the simulation results show that the passband can be tuned from 12 to 8 GHz with an insertion loss between 0.5 and 1.4 dB by sweeping the capacitance of the varactors. The proposed design decreases the chances of detection by adversary devices and assures spectrum-safe communication, thereby creating new avenues for radar stealth and target concealment.

Optimizing Absorption for Intranasal Delivery of Drugs Targeting the Central Nervous System Using Alkylsaccharide Permeation Enhancers.

Intranasal delivery of drugs offers several potential benefits related to ease of delivery, rapid onset, and patient experience, which may be of particular relevance to patients with central nervous system (CNS) conditions who experience acute events. Intranasal formulations must be adapted to address anatomical and physiological characteristics of the nasal cavity, including restricted dose volume, limited surface area, and barriers to mucosal absorption, in addition to constraints on the absorption window due to mucociliary clearance. Development of an effective formulation may utilize strategies including the addition of excipients to address the physicochemical properties of the drug within the constraints of nasal delivery. Dodecyl maltoside (DDM) and tetradecyl maltoside are alkylsaccharide permeation enhancers with well-established safety profiles, and studies have demonstrated transiently improved absorption and favorable bioavailability of several compounds in preclinical and clinical trials. Dodecyl maltoside is a component of three US Food and Drug Administration (FDA)-approved intranasal medications: diazepam for the treatment of seizure cluster in epilepsy, nalmefene for the treatment of acute opioid overdose, and sumatriptan for the treatment of migraine. Another drug product with DDM as an excipient is currently under FDA review, and numerous investigational drugs are in early-stage development. Here, we review factors related to the delivery of intranasal drugs and the role of alkylsaccharide permeation enhancers in the context of approved and future intranasal formulations of drugs for CNS conditions.