Development of a method to measure regional perfusion of the lung in anesthetized ponies using computed tomography angiography and the maximum slope model

OBJECTIVE To develop a method based on CT angiography and the maximum slope model (MSM) to measure regional lung perfusion in anesthetized ponies. ANIMALS 6 ponies. PROCEDURES Anesthetized ponies were positioned in dorsal recumbency in the CT gantry. Contrast was injected, and the lungs were imaged while ponies were breathing spontaneously and while they were mechanically ventilated. Two observers delineated regions of interest in aerated and atelectatic lung, and perfusion in those regions was calculated with the MSM. Measurements obtained with a computerized method were compared with manual measurements, and computerized measurements were compared with previously reported measurements obtained with microspheres. RESULTS Perfusion measurements obtained with the MSM were similar to previously reported values obtained with the microsphere method. While ponies were spontaneously breathing, mean ± SD perfusion for aerated and atelectatic lung regions were 4.0 ± 1.9 and 5.0 ± 1.2 mL/min/g of lung tissue, respectively. During mechanical ventilation, values were 4.6 ± 1.2 and 2.7 ± 0.7 mL/min/g of lung tissue at end expiration and 4.1 ± 0.5 and 2.7 ± 0.6 mL/min/g of lung tissue at peak inspiration. Intraobserver agreement was acceptable, but interobserver agreement was lower. Computerized measurements compared well with manual measurements. CLINICAL RELEVANCE Findings showed that CT angiography and the MSM could be used to measure regional lung perfusion in dorsally recumbent anesthetized ponies. Measurements are repeatable, suggesting that the method could be used to determine efficacy of therapeutic interventions to improve ventilation-perfusion matching and for other studies for which measurement of regional lung perfusion is necessary.

FORMULATION AND EVALUATION OF CAPTOPRIL BIOADHESIVE MICROSPHERES

In the present work, captopril microspheres using HPMCK100M, HPMCK15M and Carbopol 934 as copolymers were formulated by ionic cross linking technique (ionotropic gelation method) to deliver captopril via oral route. The technique was successfully employed to fabricate captopril microspheres and provides characteristic advantage over conventional microsphere method, which involves an “all-aqueous” system and thus avoids residual solvents in microspheres. Other methods utilize larger volume of organic solvents are costly and hazardous. Micromeritic studies revealed that the mean particle size was in the range of 512-903 μm. Increase in the polymer concentration led to increase in % yield, % drug entrapment effi ciency, particle size, % swelling and % mucoadhesion. The in vitro mucoadhesive study demonstrated that captopril microspheres using sodium alginate along with HPMCK100M as copolymer adhered to the mucus to a greater extent than the microspheres of captopril using albumin along with HPMCK15M and Carbopol 934 as copolymers.

Formulation and invitro evaluation of oral extended release microspheres of aceclofenac using various natural polymers

In the present work, bioadhesive microspheres of Aceclofenac using Sodium alginate along with Carbopol 934, Carbopol 971, HPMC K4M as copolymers were formulated to deliver Aceclofenac via oral route. The results of this investigation indicate that ionic cross-linking technique Ionotropic gelation method can be successfully employed to fabricate Aceclofenac microspheres. The technique provides characteristic advantage over conventional microsphere method, which involves an “all-aqueous” system, avoids residual solvents in microspheres. FT-IR spectra of the physical mixture revealed that the drug is compatible with the polymers and copolymers used. Micromeritic studies revealed that the mean particle size of the prepared microspheres was in the size range of 512-903µm and are suitable for bioadhesive microspheres for oral administration. The in-vitro mucoadhesive study demonstrated that microspheres of Aceclofenac using sodium alginate along with Carbopol934 as copolymer adhered to the mucus to a greater extent than the microspheres of Aceclofenac using sodium alginate along with Carbopol 971 and HPMC K4M as copolymers. The invitro drug release decreased with increase in the polymer and copolymer concentration. Analysis of drug release mechanism showed that the drug release from the formulations followed non-Fickian diffusion and the best fit model was found to be Korsmeyer-Peppas. Based on the results of evaluation tests formulation coded T4 was concluded as best formulation.

A new anti-biofilm strategy of enabling arbitrary surfaces of materials and devices with robust bacterial anti-adhesion via a spraying modified microsphere method

Despite adopting diverse strategies and fabrication methods to prevent biofilm formation, the existing sophisticated fabrication methods for sole wettable or smart surfaces and their unsatisfactory anti-adhesive durability need to be improved for their practical applications.

MUCOADHESIVE AND MICROSPHERE: A SHORT REVIEW

Microsphere constitutes an important part of novel drug delivery system by virtue of their small size and efficient carrier capacity. Due to their short residence time, bioadhesive characteristics can be coupled to microsphere to develop mucoadhesive microsphere. Bioadhesion defined as state in which two materials, at least one of which is biological in nature, are held together for a prolonged time by the way of interfacial forces. Microsphere are the carrier around drug delivery system in which particle size in ranges from 1-1000 μm range in diameter having a core of drug and entirely outer layers of polymers as coating material. Mucoadhesive microsphere have advantages like efficient absorption and enhanced bioavailability of drugs due to high surface of volume ratio, a much more intimate contact with mucus layer, controlled and sustained release of drug from dosage form and specific targeting of drug to absorption site. This study aim to provide an overview of various aspects of mucoadhesive microsphere based on various polymers, method of preparation of mucoadhesive microsphere, method of evaluation and their applications in drug delivery system.Keywords: Mucoadhesive, microsphere, bioavailability.

The history of the microsphere method for measuring blood flows with special reference to myocardial blood flow: a personal memoir

We use many types of equipment and technologies to make our measurements but give little thought to how they developed. Evolution was once described as a series of recoils from blind alleys, and this is exemplified by the gradual development of the microsphere method of measuring blood flows. The microsphere method is one of the most frequently used methods for measuring blood flow to organs and portions of organs. The method can measure myocardial blood flow with reasonable accuracy (within 10%) down to samples weighing >50 mg but probably will not do so for samples weighing 1–10 mg. Microspheres with diameters from 10 to 15 μm provide the best compromise between accurate flow measurement and retention in tissue. Radioactive labels have been almst entirely replaced by fluorescent labels, but colored microspheres and neutron-activated labels are also used. NEW & NOTEWORTHY The contributions of the various individuals who developed the microsphere method of measuring regional blood flows and how these advances took place are brought to light in this paper.

Formulation and Technology Study on the Taste Masking Granules

Objective: To investigate the formulation and technology for taste-masking granules. Methods: Clarithromycin was used as a model active pharmaceutical ingredient with bitter taste. Four preparation processes were compared, which were gelatin mono-condensation microcapsule method, calcium alginate microcapsule method, gelatin microsphere method and resin matrix granulation method. With taste masking effect and dissolution rate as evaluation indexes, the optimal preparation technology was studied. The orthogonal experiment was used to investigate the optimal formulation. Results: Clarithromycin granules prepared by the resin matrix granulation method had good taste masking effects and suitable dissolution rate. The optimal formulation was following: polyacrylic acid resin IV 0.85 g, PEG4000 0.30 g, sodium bicarbonate 0.10 g. The prepared clarithromycin granules have good taste masking effect and its dissolution in 45 min can reach 80.5%. Conclusion: The optimal formulation and technology can satisfy the request for taste masking and dissolution rate of clarithromycin granules.