In Vitro and In Vivo Evaluation of Dark Chocolate as Age-appropriate Oral Matrix.

Swallowing difficulties encountered by geriatric patients who undergo polypharmacy represent a significant challenge that hampers patient compliance and therapeutic management. As an appealing and sensory-pleasing, chocolate-based formulations have emerged as a potential alternative oral dosage form suitable for both the elderly and paediatric populations. However, the extent to which the incorporation of drugs into a chocolate matrix affects their oral availability remains unclear. Therefore, the objective of this investigation was to explore the in vitro and in vivo performance of an ibuprofen-based chocolate dosage form. A matrix based on dark chocolate and the model drug was prepared at two distinct temperatures: 50 and 80 °C. In vitro release studies revealed that ibuprofen formulated through co-melting at 80 °C exhibited a statistically significant slower drug release (p < 0.05) compared to formulations prepared at 50 °C in both FaSSGF (fasted-state simulated gastric fluid) and lipolysis media. The enzymatic degradation of chocolate in the presence of lipase accelerated in vitro ibuprofen release from chocolate matrices. To delve deeper into the bioavailability of ibuprofen within the chocolate formulations, we conducted an in vivo assessment, comparing the pharmacokinetic profiles of ibuprofen in its conventional suspension form with our chocolate-based dosage forms. A notable drop (p < 0.05) in the maximum serum concentration of ibuprofen when incorporated into co-melted or solid-suspension chocolate matrices. However, no significant differences in plasma exposure were observed between the two formulations. These findings shed a light on the potential of chocolate to extend of ibuprofen when integrated into various chocolate matrices, showcasing the potential held by these innovative formulations.

Authentication of Covid-19 Vaccines Using Synchronous Fluorescence Spectroscopy.

The present study demonstrates the potential of synchronous fluorescence spectroscopy and multivariate data analysis for authentication of COVID-19 vaccines from various manufacturers. Synchronous scanning fluorescence spectra were recorded for DNA-based and mRNA-based vaccines obtained through the NHS Central Liverpool Primary Care Network. Fluorescence spectra of DNA and DNA-based vaccines as well as RNA and RNA-based vaccines were identical to one another. The application of principal component analysis (PCA), PCA-Gaussian Mixture Models (PCA-GMM)) and Self-Organising Maps (SOM) methods to the fluorescence spectra of vaccines is discussed. The PCA is applied to extract the characteristic variables of fluorescence spectra by analysing the major attributes. The results indicated that the first three principal components (PCs) can account for 99.5% of the total variance in the data. The PC scores plot showed two distinct clusters corresponding to the DNA-based vaccines and mRNA-based vaccines respectively. PCA-GMM clustering complemented the PCA clusters by further classifying the mRNA-based vaccines and the GMM clusters revealed three mRNA-based vaccines that were not clustered with the other vaccines. SOM complemented both PCA and PCA-GMM and proved effective with multivariate data without the need for dimensions reduction. The findings showed that fluorescence spectroscopy combined with machine learning algorithms (PCA, PCA-GMM and SOM) is a useful technique for vaccination verification and has the benefits of simplicity, speed and reliability.

Preparation and Characterisation of Zinc Diethyldithiocarbamate-Cyclodextrin Inclusion Complexes for Potential Lung Cancer Treatment.

Zinc diethyldithiocarbamate (Zn (DDC)2), a disulfiram metabolite (anti-alcoholism drug), has shown a strong anti-cancer activity in vitro. However, its application was limited by its low aqueous solubility and rapid metabolism. In this study, the solubility enhancement of Zn (DDC)2 is investigated by forming inclusion complexes with cyclodextrins. The inclusion complexes were prepared using two different types of beta-cyclodextrins, SBE-CD and HP-CD. Phase solubility diagrams for the resulting solutions were assessed; subsequently, the solutions were freeze-dried for further characterisation studies using DSC, TGA, XRD, and FTIR. The cytotoxic activity of the produced inclusion complexes was evaluated on human lung carcinoma cells using the MTT assay. The solubility of Zn (DDC)2 increased significantly upon adding beta-cyclodextrins, reaching approximately 4 mg/mL for 20% w/w CD solutions. The phase solubility diagram of Zn (DDC)2 was of the Ap-type according to the Higuchi and Connors model. Characterisation studies confirmed the inclusion of the amorphous drug in the CD-Zn (DDC)2 complexes. The cytotoxicity of Zn (DDC)2 was enhanced 10-fold by the inclusion complexes compared to the free drug. Overall, the resulting CD-Zn (DDC)2 inclusion complexes have a potential for treatment against lung cancer.

Preparation and Characterization of Disulfiram and Beta Cyclodextrin Inclusion Complexes for Potential Application in the Treatment of SARS-CoV-2 via Nebulization.

Disulfiram (DS), known as an anti-alcoholism drug, has shown a potent antiviral activity. Still, the potential clinical application of DS is limited by its low water solubility and rapid metabolism. Cyclodextrins (CDs) have been widely used to improve the solubility of drugs in water. In this study, five concentrations of hydroxypropyl ß-cyclodextrin (HP) and sulfobutyl ether ß-cyclodextrin (SBE) were used to form inclusion complexes of DS for enhanced solubility. Solutions were freeze-dried, and the interaction between DS and CD was characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). In addition, the nebulization properties of the DS-CD solutions were studied. The aqueous solubility of DS increased significantly when loaded to either of both CDs. The phase solubility of both complexes was a linear function of the CD concentration (AL type). Furthermore, physicochemical characterization studies showed a potent inclusion of the drug in the CD-DS complexes. Aerosolization studies demonstrated that these formulations are suitable for inhalation. Overall, the CD inclusion complexes have great potential for the enhancement of DS solubility. However, further studies are needed to assess the efficacy of DS-CD inclusion complexes against SARS-CoV-2 via nebulization.

Evaluation of portable near-infrared spectroscopy for authentication of mRNA based COVID-19 vaccines.

Since its identification in 2019, Covid-19 has spread to become a global pandemic. Until now, vaccination in its different forms proves to be the most effective measure to control the outbreak and lower the burden of the disease on healthcare systems. This arena has become a prime target to criminal networks that spread counterfeit Covid-19 vaccines across the supply chain mainly for profit. Counterfeit vaccines provide false sense of security to individuals, heightens the risk of exposure and outbreak of the virus, and increase the risk of harm linked to Covid-19 infection. Moreover, the increase in counterfeit vaccines feeds hesitancy towards vaccination and erodes the trust in mass immunisation programmes. It is therefore of paramount importance to work on rapid and reliable methods for vaccine authentication. Subsequently this work utilised a portable and non-destructive near infrared (NIR) spectroscopic method for authentication of Covid-19 vaccines. A total of 405 Covid-19 vaccines samples, alongside their main constituents, were measured as received through glass vials. Spectral quality and bands were inspected by considering the raw spectra of the vaccines. Authentication was explored by applying principal component analysis (PCA) to the multiplicative scatter correction-first derivative spectra. The results showed that NIR spectra of the vaccine featured mainly bands corresponding to the mRNA active ingredient. Fewer bands corresponded to the excipients and protein spectra. The vaccines NIR spectra were strongly absorbing with maximum absorbances up to 2.7 absorbance units and that differentiated them from samples containing normal saline only (constituent reported for counterfeit Covid-19 vaccines). Clustering based on PCA offered optimal authentication of Covid-19 vaccines when applied over the range of 9000-4000 cm-1These findings shed light on the potential of using NIR for analysing Covid-19 vaccines and presents a rapid and effective initial technique for Covid-19 vaccine authentication.

Authentication of Antibiotics Using Portable Near-Infrared Spectroscopy and Multivariate Data Analysis.

Counterfeit medicines represent a global public health threat warranting the development of accurate, rapid, and nondestructive methods for their identification. Portable near-infrared (NIR) spectroscopy offers this advantage. This work sheds light on the potential of combining NIR spectroscopy with principal component analysis (PCA) and soft independent modelling of class analogy (SIMCA) for authenticating branded and generic antibiotics. A total of 23 antibiotics were measured "nondestructively" using a portable NIR spectrometer. The antibiotics corresponded to six different active pharmaceutical ingredients being: amoxicillin trihydrate and clavulanic acid, azithromycin dihydrate, ciprofloxacin hydrochloride, doxycycline hydrochloride, and ofloxacin. NIR spectra were exported into Matlab R2018b where data analysis was applied. The results showed that the NIR spectra of the medicines showed characteristic features that corresponded to the main excipient(s). When combined with PCA, NIR spectroscopy could distinguish between branded and generic medicines and could classify medicines according to their manufacturing sources. The PCA scores showed the distinct clusters corresponding to each group of antibiotics, whereas the loadings indicated which spectral features were significant. SIMCA provided more accurate classification over PCA for all antibiotics except ciprofloxacin which products shared many overlapping excipients. In summary, the findings of the study demonstrated the feasibility of portable NIR as an initial method for screening antibiotics.

High performance liquid chromatography - Mass spectrometric bioanalytical method for the determination of dapoxetine in human plasma: Application for bioequivalence study.

Dapoxetine is an oral medication used for treatment of premature ejaculation (PE) in men aged (18-64 years). In this study, we present a validated, precise and sensitive method for determination of dapoxetine in human plasma by liquid chromatography/ electrospray ionization-tandem mass spectrometry. Dapoxetine and the internal standard (Dapoxetine- d6) were extracted from plasma via liquid-liquid extraction (LLE). The LC separation was performed utilizing ACE C8 (4.6 X50) mm, 5 µm column. The mobile phase was composed of acetonitrile and buffer (0.01 M Ammonium acetate +0.02% Formic acid solution) (85:15, v/v). The method was linear within the concentration range of 5.0-600 ng/mL for Dapoxetine in human plasma. Short analytical run was achieved with 1.6 min run time. Intra-day and inter-day accuracy was between 97 and 106% with precision (CV, %) of ≤ 5% achieved across all the quality control samples. Dapoxetine was stable in several conditions with recovery rates > 90%. This method was utilized successfully in clinical pharmacokinetic study following oral administration of 60 mg Dapoxetine tablets in 36 healthy male subjects. The result for all 90% confidence intervals were within the preset ranges. The method proved to be highly reproducible and sensitive and thus can be employed in bioequivalence studies and large scale sample analysis of Dapoxetine.

Development, characterization and stability evaluation of ciprofloxacin-loaded parenteral nutrition nanoemulsions.

In this study, two licensed total parenteral nanoemulsion formulations (Clinoleic® and Intralipid®) were loaded with ciprofloxacin (CP). The physicochemical characteristics and stability profiles of the formulations were investigated using a range of drug concentrations. Furthermore, formulation stability was evaluated over a period of six months at room temperature (RT) or 4 °C. Loading CP into nanoemulsions resulted in no significant differences in their measured droplet size, polydispersity index (PI), zeta potential, and pH. Drug entrapment efficiency (EE) was relatively high for all formulations, regardless of nanoemulsion type, and the drug release was sustained over 24 h. Stability studies of all formulations were performed at 4 °C and RT for 180 and 60 days, respectively. At 4 °C for 180 days, both Clinoleic® and Intralipid® formulations at a range of drug concentrations (1-10 mg/ml) showed high stabilities measured periodically by the average droplet sizes, PI, pH, and zeta potential values. Similar results, but pH values, were shown when the formulations for both nanoemulsion stored at RT for 60 days. Overall, this study has shown that CP was successfully loaded into clinically licensed TPN lipid nanoemulsions. The resultant CP-loaded nanoemulsion formulations demonstrated desirable physicochemical properties and were stable upon storage at 4 °C for up to six months.

Embedded 3D Printing of Novel Bespoke Soft Dosage Form Concept for Pediatrics.

Embedded three-dimensional printing (e-3DP) is an emerging method for additive manufacturing where semi-solid materials are extruded within a solidifying liquid matrix. Here, we present the first example of employing e-3DP in the pharmaceutical field and demonstrate the fabrication of bespoke chewable dosage forms with dual drug loading for potential use in pediatrics. LegoTM-like chewable bricks made of edible soft material (gelatin-based matrix) were produced by directly extruding novel printing patterns of model drug ink (embedded phase) into a liquid gelatin-based matrix (embedding phase) at an elevated temperature (70 °C) to then solidify at room temperature. Dose titration of the two model drugs (paracetamol and ibuprofen) was possible by using specially designed printing patterns of the embedded phase to produce varying doses. A linearity [R2 = 0.9804 (paracetamol) and 0.9976 (ibuprofen)] was achieved between percentage of completion of printing patterns and achieved doses using a multi-step method. The impact of embedded phase rheological behavior, the printing speed and the needle size of the embedded phase were examined. Owning to their appearance, modular nature, ease of personalizing dose and geometry, and tailoring and potential inclusion of various materials, this new dosage form concept holds a substantial promise for novel dosage forms in pediatrics.

Tailored on demand anti-coagulant dosing: An in vitro and in vivo evaluation of 3D printed purpose-designed oral dosage forms.

Coumarin therapy has been associated with high levels of inter- and intra-individual variation in the required dose to reach a therapeutic anticoagulation outcome. Therefore, a dynamic system that is able to achieve accurate delivery of a warfarin dose is of significant importance. Here we assess the ability of 3D printing to fabricate and deliver tailored individualised precision dosing using in-vitro and in-vivo models. Sodium warfarin loaded filaments were compounded using hot melt extrusion (HME) and further fabricated via fused deposition modelling (FDM) 3D printing to produce capsular-ovoid-shaped dosage forms loaded at 200 or 400 µg dose. The solid dosage forms and comparator warfarin aqueous solutions were administered by oral gavage to Sprague-Dawley rats. A novel UV imaging approach indicated that the erosion of the methacrylate matrix was at a rate of 16.4 and 15.2 µm/min for horizontal and vertical planes respectively. In vivo, 3D printed forms were as proportionately effective as their comparative solution form in doubling plasma exposure following a doubling of warfarin dose (184% versus 192% respectively). The 3D printed ovoids showed a lower Cmax of warfarin (1.51 and 3.33 mg/mL versus 2.5 and 6.44 mg/mL) and a longer Tmax (6 and 3.7 versus 4 and 1.5 h) in comparison to liquid formulation. This work demonstrates for the first time in vivo, the potential of FDM 3D printing to produce a tailored specific dosage form and to accurately titrate coumarin dose response to an individual patient.

Tablet fragmentation without a disintegrant: A novel design approach for accelerating disintegration and drug release from 3D printed cellulosic tablets.

Fused deposition modelling (FDM) 3D printing has shown the most immediate potential for on-demand dose personalisation to suit particular patient's needs. However, FDM 3D printing often involves employing a relatively large molecular weight thermoplastic polymer and results in extended release pattern. It is therefore essential to fast-track drug release from the 3D printed objects. This work employed an innovative design approach of tablets with unique built-in gaps (Gaplets) with the aim of accelerating drug release. The novel tablet design is composed of 9 repeating units (blocks) connected with 3 bridges to allow the generation of 8 gaps. The impact of size of the block, the number of bridges and the spacing between different blocks was investigated. Increasing the inter-block space reduced mechanical resistance of the unit, however, tablets continued to meet pharmacopeial standards for friability. Upon introduction into gastric medium, the 1 mm spaces gaplet broke into mini-structures within 4 min and met the USP criteria of immediate release products (86.7% drug release at 30 min). Real-time ultraviolet (UV) imaging indicated that the cellulosic matrix expanded due to swelling of hydroxypropyl cellulose (HPC) upon introduction to the dissolution medium. This was followed by a steady erosion of the polymeric matrix at a rate of 8 µm/min. The design approach was more efficient than a comparison conventional formulation approach of adding disintegrants to accelerate tablet disintegration and drug release. This work provides a novel example where computer-aided design was instrumental at modifying the performance of solid dosage forms. Such an example may serve as the foundation for a new generation of dosage forms with complicated geometric structures to achieve functionality that is usually achieved by a sophisticated formulation approach.

Channelled tablets: An innovative approach to accelerating drug release from 3D printed tablets.

Conventional immediate release dosage forms involve compressing the powder with a disintegrating agent that enables rapid disintegration and dissolution upon oral ingestion. Among 3D printing technologies, the fused deposition modelling (FDM) 3D printing technique has a considerable potential for patient-specific dosage forms. However, the use of FDM 3D printing in tablet manufacturing requires a large portion of polymer, which slows down drug release through erosion and diffusion mechanisms. In this study, we demonstrate for the first time the use of a novel design approach of caplets with perforated channels to accelerate drug release from 3D printed tablets. This strategy has been implemented using a caplet design with perforating channels of increasing width (0.2, 0.4, 0.6, 0.8 or 1.0mm) and variable length, and alignment (parallel or at right angle to tablet long axis). Hydrochlorothiazide (BCS class IV drug) was chosen as the model drug as enhanced dissolution rate is vital to guarantee oral bioavailability. The inclusion of channels exhibited an increase in the surface area/volume ratio, however, the release pattern was also influenced by the width and the length of the channel. A channel width was ≥0.6mm deemed critical to meet the USP criteria of immediate release products. Shorter multiple channels (8.6mm) were more efficient at accelerating drug release than longer channels (18.2mm) despite having comparable surface area/mass ratio. This behaviour may be linked to the reduced flow resistance within the channels and the faster fragmentation during dissolution of these tablets. In conclusion, the width and length of the channel should be carefully considered in addition to surface area/mass when optimizing drug release from 3D printed designs. The incorporation of short channels can be adopted in the designs of dosage forms, implants or stents to enhance the release rate of eluting drug from polymer-rich structures.

Fabricating a Shell-Core Delayed Release Tablet Using Dual FDM 3D Printing for Patient-Centred Therapy.

PURPOSE: Individualizing gastric-resistant tablets is associated with major challenges for clinical staff in hospitals and healthcare centres. This work aims to fabricate gastric-resistant 3D printed tablets using dual FDM 3D printing. METHODS: The gastric-resistant tablets were engineered by employing a range of shell-core designs using polyvinylpyrrolidone (PVP) and methacrylic acid co-polymer for core and shell structures respectively. Filaments for both core and shell were compounded using a twin-screw hot-melt extruder (HME). CAD software was utilized to design a capsule-shaped core with a complementary shell of increasing thicknesses (0.17, 0.35, 0.52, 0.70 or 0.87 mm). The physical form of the drug and its integrity following an FDM 3D printing were assessed using x-ray powder diffractometry (XRPD), thermal analysis and HPLC. RESULTS: A shell thickness ≥0.52 mm was deemed necessary in order to achieve sufficient core protection in the acid medium. The technology proved viable for incorporating different drug candidates; theophylline, budesonide and diclofenac sodium. XRPD indicated the presence of theophylline crystals whilst budesonide and diclofenac sodium remained amorphous in the PVP matrix of the filaments and 3D printed tablets. Fabricated tablets demonstrated gastric resistant properties and a pH responsive drug release pattern in both phosphate and bicarbonate buffers. CONCLUSIONS: Despite its relatively limited resolution, FDM 3D printing proved to be a suitable platform for a single-process fabrication of delayed release tablets. This work reveals the potential of dual FDM 3D printing as a unique platform for personalising delayed release tablets to suit an individual patient's needs.

Adaptation of pharmaceutical excipients to FDM 3D printing for the fabrication of patient-tailored immediate release tablets.

This work aims to employ fused deposition modelling 3D printing to fabricate immediate release pharmaceutical tablets with several model drugs. It investigates the addition of non-melting filler to methacrylic matrix to facilitate FDM 3D printing and explore the impact of (i) the nature of filler, (ii) compatibility with the gears of the 3D printer and iii) polymer: filler ratio on the 3D printing process. Amongst the investigated fillers in this work, directly compressible lactose, spray-dried lactose and microcrystalline cellulose showed a level of degradation at 135°C whilst talc and TCP allowed consistent flow of the filament and a successful 3D printing of the tablet. A specially developed universal filament based on pharmaceutically approved methacrylic polymer (Eudragit EPO) and thermally stable filler, TCP (tribasic calcium phosphate) was optimised. Four model drugs with different physicochemical properties were included into ready-to-use mechanically stable tablets with immediate release properties. Following the two thermal processes (hot melt extrusion (HME) and fused deposition modelling (FDM) 3D printing), drug contents were 94.22%, 88.53%, 96.51% and 93.04% for 5-ASA, captopril, theophylline and prednisolone respectively. XRPD indicated that a fraction of 5-ASA, theophylline and prednisolone remained crystalline whilst captopril was in amorphous form. By combining the advantages of thermally stable pharmaceutically approved polymers and fillers, this unique approach provides a low cost production method for on demand manufacturing of individualised dosage forms.

A Lower Temperature FDM 3D Printing for the Manufacture of Patient-Specific Immediate Release Tablets.

PURPOSE: The fabrication of ready-to-use immediate release tablets via 3D printing provides a powerful tool to on-demand individualization of dosage form. This work aims to adapt a widely used pharmaceutical grade polymer, polyvinylpyrrolidone (PVP), for instant on-demand production of immediate release tablets via FDM 3D printing. METHODS: Dipyridamole or theophylline loaded filaments were produced via processing a physical mixture of API (10%) and PVP in the presence of plasticizer through hot-melt extrusion (HME). Computer software was utilized to design a caplet-shaped tablet. The surface morphology of the printed tablet was assessed using scanning electron microscopy (SEM). The physical form of the drugs and its integrity following an FDM 3D printing were assessed using x-ray powder diffractometry (XRPD), thermal analysis and HPLC. In vitro drug release studies for all 3D printed tablets were conducted in a USP II dissolution apparatus. RESULTS: Bridging 3D printing process with HME in the presence of a thermostable filler, talc, enabled the fabrication of immediate release tablets at temperatures as low as 110°C. The integrity of two model drugs was maintained following HME and FDM 3D printing. XRPD indicated that a portion of the loaded theophylline remained crystalline in the tablet. The fabricated tablets demonstrated excellent mechanical properties, acceptable in-batch variability and an immediate in vitro release pattern. CONCLUSIONS: Combining the advantages of PVP as an impeding polymer with FDM 3D printing at low temperatures, this approach holds a potential in expanding the spectrum of drugs that could be used in FDM 3D printing for on demand manufacturing of individualised dosage forms.

Emergence of 3D Printed Dosage Forms: Opportunities and Challenges.

The recent introduction of the first FDA approved 3D-printed drug has fuelled interest in 3D printing technology, which is set to revolutionize healthcare. Since its initial use, this rapid prototyping (RP) technology has evolved to such an extent that it is currently being used in a wide range of applications including in tissue engineering, dentistry, construction, automotive and aerospace. However, in the pharmaceutical industry this technology is still in its infancy and its potential yet to be fully explored. This paper presents various 3D printing technologies such as stereolithographic, powder based, selective laser sintering, fused deposition modelling and semi-solid extrusion 3D printing. It also provides a comprehensive review of previous attempts at using 3D printing technologies on the manufacturing dosage forms with a particular focus on oral tablets. Their advantages particularly with adaptability in the pharmaceutical field have been highlighted, which enables the preparation of dosage forms with complex designs and geometries, multiple actives and tailored release profiles. An insight into the technical challenges facing the different 3D printing technologies such as the formulation and processing parameters is provided. Light is also shed on the different regulatory challenges that need to be overcome for 3D printing to fulfil its real potential in the pharmaceutical industry.

Extraction and RP-HPLC determination of taxol in rat plasma, cell culture and quality control samples.

A rapid, sensitive, selective and validated reverse phase high-performance liquid chromatography (RP-HPLC) method for the estimation of paclitaxel in micro-sample of rat plasma and in culture of cancer cells was performed in this study. The mobile phase consisted of an optimized mixture of methanol:water: trifluroacetic acid (80: 20: 0.1, v/v/v). Column elution at a flow rate of 1 mL/minute with UV detection at 225 nm at room temperature was used. The RP-HPLC method was successfully applied for the determination of paclitaxel in plasma samples and in culture of cancer cells with nano-quantity of estimation. The validation studies were performed in accordance with the International Conference on Harmonization (ICH) guidelines. The intra- and inter-day precision showed that the coefficients of variation ranged from 1.07% to 4.27% at different levels of concentrations. To the best of our knowledge, this study also reported for the first time the optimization of different solvents for effective extraction of paclitaxel wherein tert.-butyl methyl ether (TBME): diethyl ether (DEE) in 50: 50 v/v composition was found most efficient with extraction efficiency ranging between 77.99% and 91.74% and between 76.14 and 93.66% in the plasma and cell culture, respectively. This proposed method was successfully applied to study the pharmacokinetics of paclitaxel and the influence of verapamil and all-trans retinoic acid (atRA) on paclitaxel pharmacokinetics in rat models. This proposed method might emerge as a valuable aid in the laboratory monitoring of paclitaxel in a variety of in vitro as well as in vivo scenarios.

A study of the effects of sodium halides on the performance of air-jet and vibrating-mesh nebulizers.

The influence of sodium halide electrolytes on aerosols generated from the Aeroneb Pro vibrating mesh nebulizer and the Sidestream air-jet nebulizer has been evaluated. Fluids with a range of concentrations of Na halides (i.e. NaF, NaCl, NaBr and NaI) were used as nebulizer solutions and their effect on aerosol properties such as total aerosol output, fine particle fraction (FPF), volume median diameter (VMD) and predicted regional airway deposition were investigated. For both nebulizers, the inclusion of electrolyte significantly enhanced the aerosol properties compared with HPLC grade (deionized) water. Aerosol output, FPF and aerosol fraction less than 2.15 µm were directly proportional to electrolyte concentration. Furthermore, the proportion of aerosols that are likely to deposit in the oropharyngeal region, and the VMD of the droplets were inversely related to the electrolyte concentration for both nebulizers. In general, the inclusion of electrolytes had a greater impact on the aerosol properties of the vibrating-mesh nebulizer. In the Aeroneb Pro, NaI 2.0% (w/v) was the optimum solution as it generated the highest aerosol output, FPF and output fraction below 2.15 µm with the lowest VMD and minimal predicted oropharyngeal deposition. This was attributed to the polarizing ability of iodide ions present in the largest quantity at the air-water interface. This study has shown that the Aeroneb Pro vibrating-mesh device demonstrated greatly enhanced aerosol properties when halides were included in the nebulizer solutions.

Physiological bicarbonate buffers: stabilisation and use as dissolution media for modified release systems.

Bicarbonate media are reflective of the ionic composition and buffer capacity of small intestinal luminal fluids. Here we investigate methods to stabilise bicarbonate buffers which can be readily applied to USP-II dissolution apparatus. The in vitro drug release behaviour of three enteric coated mesalazine (mesalamine) products is investigated. Asacol 400 mg and Asacol 800 mg (Asacol HD) and the new generation, high dose (1200 mg) delayed and sustained release formulation, Mezavant (Lialda), are compared in pH 7.4 Krebs bicarbonate and phosphate buffers. Bicarbonate stabilisation was achieved by: continuous sparging of the medium with 5% CO(2)(g), application of a layer of liquid paraffin above the medium, or a specially designed in-house seal device that prevents CO(2)(g) loss. Each of the products displayed a delayed onset of drug release in physiological bicarbonate media compared to phosphate buffer. Moreover, Mezavant displayed a zero-order, sustained release profile in phosphate buffer; in bicarbonate media, however, this slow drug release was no longer apparent and a profile similar to that of Asacol 400 mg was observed. These similar release patterns of Asacol 400 mg and Mezavant displayed in bicarbonate media are in agreement with their pharmacokinetic profiles in humans. Bicarbonate media provide a better prediction of the in vivo behaviour of the mesalazine preparations investigated.