We report a study of self-assembled beta-pleated sheets in B. mori silk fibroin films using thermal analysis and infrared spectroscopy. B. mori silk fibroin may stand as an exemplar of fibrous proteins containing crystalline beta-sheets. Materials were prepared from concentrated solutions (2−5 wt % fibroin in water) and then dried to achieve a less ordered state without beta-sheets. Crystallization of beta-pleated sheets was effected either by heating the films above the glass transition temperature (Tg) and holding isothermally or by exposure to methanol. The fractions of secondary structural components including random coils, alpha-helices, beta-pleated sheets, turns, and side chains were evaluated using Fourier self-deconvolution (FSD) of the infrared absorbance spectra. The silk fibroin films were studied thermally using temperature-modulated differential scanning calorimetry (TMDSC) to obtain the reversing heat capacity. The increment of the reversing heat capacity ΔCp0(Tg) at the glass transition fo...

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Determining Beta Sheet Crystallinity in Fibrous Proteins by Thermal Analysis and Infrared Spectroscopy

Manufacturing of solid dispersions of poorly water soluble drugs by spray drying: formulation and process considerations.

https://uhra.herts.ac.uk/bitstream/handle/2299/6166/905436.pdf;sequence=1

Advances in oral transmucosal drug delivery.

Thin films as an emerging platform for drug delivery

Transdermal patches are now widely used as cosmetic, topical and transdermal delivery systems. These patches represent a key outcome from the growth in skin science, technology and expertise developed through trial and error, clinical observation and evidence-based studies that date back to the first existing human records. This review begins with the earliest topical therapies and traces topical delivery to the present-day transdermal patches, describing along the way the initial trials, devices and drug delivery systems that underpin current transdermal patches and their actives. This is followed by consideration of the evolution in the various patch designs and their limitations as well as requirements for actives to be used for transdermal delivery. The properties of and issues associated with the use of currently marketed products, such as variability, safety and regulatory aspects, are then described. The review concludes by examining future prospects for transdermal patches and drug delivery systems, such as the combination of active delivery systems with patches, minimally invasive microneedle patches and cutaneous solutions, including metered-dose systems.

https://bpspubs.onlinelibrary.wiley.com/doi/epdf/10.1111/bph.13059

Transdermal patches: history, development and pharmacology

A focus on mucoadhesive polymers and their application in buccal dosage forms

Introduction: Transdermal patches and medicated plasters (patch) represent well-established prolonged release dosage forms. Even if satisfactory adhesion to the skin is strictly linked to the efficacy and safety of the therapeutic treatment, nowadays numerous reports of in vivo ‘adhesion lacking’ are still addressed to regulatory agencies. The adhesive properties of a patch should be characterized considering i) the ability to form a bond with the surface of another material on brief contact and under light pressure (tack); ii) the resistance of the adhesive to flow (shear adhesion); and iii) the force required to peel away a patch from a surface (peel adhesion). Areas covered: In this manuscript, the most widely used methods to measure adhesive properties during development studies are described, along with the quality control of patches. The influence of formulative variables on patch adhesive properties, and their possible relationship with the in vivo adhesion performances, is also discussed. Expert o...

Adhesive properties: a critical issue in transdermal patch development.

This work aimed to develop a fast-dissolving film made of low dextrose equivalent maltodextrins (MDX) containing nicotine hydrogen tartrate salt (NHT). Particular attention was given to the selection of the suitable taste-masking agent (TMA) and the characterisation of the ductility and flexibility under different mechanical stresses. MDX with two different dextrose equivalents (DEs), namely DE 6 and DE 12, were selected in order to evaluate the effect of polymer molecular weight on film tensile properties. The bitterness and astringency intensity of NHT and the suppression effect of several TMA were evaluated by a Taste-Sensing System. The films were characterised in term of NHT content, tensile properties, disintegration time and drug dissolution test. As expected, placebo films made of MDX DE 6 appeared stiffer and less ductile than film prepared using MDX DE 12. The films disintegrated within 10 s. Among the tested TMA, the milk and mint flavours resulted particularly suitable to mask the taste of NHT. The addition of NHT and taste-masking agents affected film tensile properties; however, the effect of the addition of these components can be counterweighted by modulating the glycerine content and/or the MDX molecular weight. The feasibility of NHT loaded fast-dissolving films was demonstrated.

/pdf/nicotine-fast-dissolving-films-made-of-maltodextrins-a-4qy86i8daq.pdf

Nicotine Fast Dissolving Films Made of Maltodextrins: A Feasibility Study

Context: The selection of a proper taste-masking agent (TMA) is a critical issue in the development of fast‐dissolving films containing bitter drugs. Objective: This work is aimed to evaluate the suppression of the bitter taste of a maltodextrin fast-dissolving film loaded with 13.4 mg sodium diclofenac (DS) by adding TMAs. Methods: The films were prepared by casting and drying aqueous mixtures of maltodextrin (DE = 6), glycerin, sorbitan oleate, and DS. Films were characterized in terms of thickness, tensile properties, film disintegration time, and drug dissolution time. The bitterness intensity of DS and the masking effect of TMAs were evaluated by an electronic tongue. Results: The ‘mint’ and ‘licorice’ flavors and sucralose mixture resulted appropriate to mask DS bitterness as confirmed by a panel of volunteers. The addition of these TMAs did not significantly affect the film disintegration time (15–20 seconds) and DS dissolution rate (about 5 minutes). Conclusion: The electronic tongue was allowed t...

Diclofenac fast-dissolving film: suppression of bitterness by a taste-sensing system

This work aims to elucidate the mechanism by which N-methylpyrrolidone (NMP) enhances the skin permeation of a compound by combining experimental data with molecular dynamic (MD) simulations. The addition of 10% NMP significantly increased the propranolol (PR) permeation through the human epidermis (∼ 15 μg/cm(2) vs ∼ 30 μg/cm(2)) while resulting inefficacious on hydrocortisone (HC) diffusion. No significant alterations in the stratum corneum structure were found after the in vitro treatment of human epidermis with NMP dispersed in mineral oil or water by attenuated total reflectance Fourier transform infrared (ATR-FTIR) analyses. MD simulations revealed the formation of a complex by H-bonds and the π-π stacking interactions between the NMP's amido group and the drug's aromatic systems. The size of the depicted NMP/PR clusters was in line with the hydrodynamic radius derived by dynamic light scattering analyses (∼ 2.00 nm). Conversely, no interaction, and consequently cluster formation, between NMP and HC occurred. These results suggest that NMP is effective in enhancing the drug permeation through human epidermis by a cotransport mechanism when NMP/drug interaction occurs.

Chiara G.M. Gennari

Papers

A focus on mucoadhesive polymers and their application in buccal dosage forms

Adhesive properties: a critical issue in transdermal patch development.

Nicotine Fast Dissolving Films Made of Maltodextrins: A Feasibility Study

Diclofenac fast-dissolving film: suppression of bitterness by a taste-sensing system

An insight into the skin penetration enhancement mechanism of n-methylpyrrolidone