Bahijja Tolulope Raimi-Abraham

Formation of protein and protein-gold nanoparticle stabilized microbubbles by pressurized gyration.

A one-pot single-step novel process has been developed to form microbubbles up to 250 μm in diameter using a pressurized rotating device. The microbubble diameter is shown to be a function of rotational speed and working pressure of the processing system, and a modified Rayleigh-Plesset equation has been derived to explain the bubble-forming mechanism. A parametric plot is constructed to identify a rotating speed and working pressure regime, which allows for continuous bubbling. Bare protein (lysozyme) microbubbles generated in this way exhibit a morphological change, resulting in microcapsules over a period of time. Microbubbles prepared with gold nanoparticles at the bubble surface showed greater stability over a time period and retained the same morphology. The functionalization of microbubbles with gold nanoparticles also rendered optical tunability and has promising applications in imaging, biosensing, and diagnostics.

Generation of poly(N-vinylpyrrolidone) nanofibres using pressurised gyration

The ability to generate nanofibres useful for biomedical applications at bench and at a larger scale is a significant manufacturing challenge. In this study, we demonstrate that it is possible to generate nanofibre meshes of poly(N-vinylpyrrolidone) (PVP) using pressurised gyration. The effects of altering polymer molecular weight and concentration on fibre morphology and size have been investigated, with identification of minimum values for both parameters for successful fibre fabrication. In addition, we note that changing the molecular weight may result in changes to the Fourier Transform Infrared (FTIR) spectra associated with changes in fibre intramolecular bond strength and arrangement. Overall the study has demonstrated that pressure gyration represents a feasible means of producing nanofibres (470-970nm) on a scale commensurate with commercial viability and have identified key parameters that influence mesh structure.

Development and Characterization of Amorphous Nanofiber Drug Dispersions Prepared Using Pressurized Gyration

Nanofibrous systems are attracting increasing interest as a means of drug delivery, although a significant limitation to this approach has been manufacture on a scale commensurate with dosage form production. However, recent work has suggested that nanofibers may be successfully manufactured on a suitable scale using the novel process of pressurized gyration (PG). In this study, we explore the potential of PG as a novel means of generating amorphous solid dispersions of poorly water-soluble drugs with enhanced dissolution performance. We examine the effect of increasing drug loading on fiber properties including size, surface characteristics, and the physical state of both components. Dispersions of ibuprofen in poly(vinylpyrrolidone) (PVP) were prepared (up to 50% w/w loading) and characterized using a range of imaging, thermal, diffraction, and spectroscopic techniques, while the release profiles were studied using sink and non-sink (pH 1.0) conditions. The drug was found to be dispersed on a molecular basis within the fibers; attenuated total reflection FTIR indicated evidence for a direct interaction between the drug and polymer at lower drug loading by the identification of a strong single band in the carbonyl region and amide region of ibuprofen and PVP respectively. Dissolution studies under sink conditions indicated a substantial increase in release rate, while non-sink studies showed evidence for supersaturation. It is concluded that PG presents a viable method for the production of drug-loaded nanofibers for oral administration with enhanced in vitro dissolution rate enhancement.

Development of micro-fibrous solid dispersions of poorly water-soluble drugs in sucrose using temperature-controlled centrifugal spinning

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Taking the guesswork out of supplying multicompartment compliance aids: do pharmacists require further guidance on medication stability?

The purpose of this article is to identify information that is currently available to pharmacists concerning the stability of medications repackaged into multicompartment compliance aids (MCAs). This article explores the potential risks associated with repackaging medications into MCAs for pharmacists who supply and patients who use them.

Solid microcrystalline dispersion films as a new strategy to improve the dissolution rate of poorly water soluble drugs: a case study using olanzapine

In this study, we evaluate the dissolution rate enhancement of solid microcrystalline dispersion (SMD) films of olanzapine (OLZ) formulated with four water-soluble polymers namely poly(N-vinylpyrrolidone) (PVP), poloxamer 188 (P188), poloxamer 407 (P407) and Soluplus(®) (SLP). Prepared formulations were characterised to determine particle size, morphology, hydrogen bonding interactions, thermal characteristics as well as in vitro dissolution studies conducted under sink conditions (pH 6.8). Particle size of OLZ in all formulations ranged between 42 and 58μm. Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), Differential Scanning Calorimetry (DSC) and Hot-Stage Microscopy (HSM) studies confirmed OLZ was well maintained in its crystalline state during the formulation process. In vitro dissolution studies showed immediate drug release from all formulation when compared to the drug alone. The greatest increase in in vitro dissolution rate was observed in formulations containing P188 most likely due to its enhanced hydrophilic and surfactant properties compared to the other agents used. Overall, this study successfully generated OLZ loaded SMD films with improved in vitro dissolution rates which is highly likely to result in improved oral bioavailability in vivo.

The development of progesterone-loaded nanofibers using pressurized gyration: A novel approach to vaginal delivery for the prevention of pre-term birth

Recent evidence has continued to support the applicability of progesterone in preventing preterm birth, hence the development of an appropriate vaginal delivery system for this drug would be of considerable interest. Here, we describe the development of progesterone-loaded bioadhesive nanofibers using pressurized gyration for potential incorporation into a vaginal insert, with a particular view to addressing the challenges of incorporating a poorly water-soluble drug into a hydrophilic nanofiber carrier. Polyethylene oxide and carboxymethyl cellulose were chosen as polymers to develop the carrier systems, based on previous evidence of their yielding mucoadhesive nanofibers using the pressurized gyration technique. The fabrication parameters such as solvent system, initial drug loading and polymer composition were varied to facilitate optimisation of fiber structure and efficiency of drug incorporation. Such studies resulted in the formation of nanofibers with satisfactory surface appearance, diameters in the region of 400 nm and loading of up to 25% progesterone. Thermal and spectroscopic analyses indicated that the drug was incorporated in a nanocrystalline state. Release from the drug-loaded fibers indicated comparable rates of progesterone dissolution to that of Cyclogest, a commercially available progesterone pessary, allowing release over a period of hours. Overall, the study has shown that pressurized gyration may produce bioadhesive progesterone-loaded nanofibers which have satisfactory loading of a poorly water-soluble drug as well as having suitable structural and release properties. The technique is also capable of producing fibers at a yield commensurate with practical applicability, hence we believe that the approach shows considerable promise for the development of progesterone dosage forms for vaginal application.

Mucoadhesion of Progesterone-Loaded Drug Delivery Nanofiber Constructs

Mucoadhesive delivery systems have attracted remarkable interest recently, especially for their potential to prolong dosage form resident times at sites of application such as the vagina or nasal cavity, thereby improving convenience and compliance as a result of less frequent dosage. Mucoadhesive capabilities need to be routinely quantified during the development of these systems. This is however logistically challenging due to difficulties in obtaining and preparing viable mucosa tissues for experiments. Utilizing artificial membranes as a suitable alternative for quicker and easier analyses of mucoadhesion of these systems is currently being explored. In this study, the mucoadhesive interactions between progesterone-loaded fibers (with varying carboxymethyl cellulose (CMC) content) and either artificial (cellulose acetate) or mucosa membranes are investigated by texture analysis and results across models are compared. Mucoadhesion to artificial membrane was about 10 times that of mucosa, though statistically significant ( p = 0.027) association between the 2 data sets was observed. Furthermore, a hypothesis relating fiber-mucosa interfacial roughness (and unfilled void spaces on mucosa) to mucoadhesion, deduced from some classical mucoadhesion theories, was tested to determine its validity. Points of interaction between the fiber and mucosa membrane were examined using atomic force microscopy (AFM) to determine the depths of interpenetration and unfilled voids/roughness, features crucial to mucoadhesion according to the diffusion and mechanical theories of mucoadhesion. A Kendalls tau and Goodman-Kruskals gamma tests established a monotonic relationship between detaching forces and roughness, significant with p-values of 0.014 and 0.027, respectively. A similar relationship between CMC concentration and interfacial roughness was also confirmed. We conclude that AFM analysis of surface geometry following mucoadhesion can be explored for quantifying mucoadhesion as data from interfacial images correlates significantly with corresponding detaching forces, a well-established function of mucoadhesion.

Microfibrous Solid Dispersions of Poorly Water-Soluble Drugs Produced via Centrifugal Spinning: Unexpected Dissolution Behavior on Recrystallization

Temperature-controlled, solvent-free centrifugal spinning may be used as a means of rapid production of amorphous solid dispersions in the form of drug-loaded sucrose microfibers. However, due to the high content of amorphous sucrose in the formulations, such microfibers may be highly hygroscopic and unstable on storage. In this study, we explore both the effects of water uptake of the microfibers and the consequences of deliberate recrystallization for the associated dissolution profiles. The stability of sucrose microfibers loaded with three selected BCS class II model drugs (itraconazole (ITZ), olanzapine (OLZ), and piroxicam (PRX)) was investigated under four different relative humidity conditions (11, 33, 53, and 75% RH) at 25 °C for 8 months, particularly focusing on the effect of the highest level of moisture (75% RH) on the morphology, size, drug distribution, physical state, and dissolution performance of microfibers. While all samples were stable at 11% RH, at 33% RH the ITZ-sucrose system showed greater resistance against devitrification compared to the OLZ- and PRX-sucrose systems. For all three samples, the freshly prepared microfibers showed enhanced dissolution and supersaturation compared to the drug alone and physical mixes; surprisingly, the dissolution advantage was largely maintained or even enhanced (in the case of ITZ) following the moisture-induced recrystallization under 75% RH. Therefore, this study suggests that the moisture-induced recrystallization process may result in considerable dissolution enhancement compared to the drug alone, while overcoming the physical stability risks associated with the amorphous state.

Benefits of enhancing international mobility of pharmacy students

Academics at University College London (UCL) School of Pharmacy have recognized the benefits of enhancing the international mobility of undergraduate pharmacy students and have a history of providing research experience to visiting international students with the expectation that it will contribute