Hyaluronic Acid Hydrogels for Controlled Pulmonary Drug Delivery-A Particle Engineering Approach

Hydrogels warrant attention as a potential material for use in sustained pulmonary drug delivery due to their swelling and mucoadhesive features. Herein, hyaluronic acid (HA) is considered a promising material due to its therapeutic potential, the effect on lung inflammation, and possible utility as an excipient or drug carrier. In this study, the feasibility of using HA hydrogels (without a model drug) to engineer inhalation powders for controlled pulmonary drug delivery was assessed. A combination of chemical crosslinking and spray-drying was proposed as a novel methodology for the preparation of inhalation powders. Different crosslinkers (urea; UR and glutaraldehyde; GA) were exploited in the hydrogel formulation and the obtained powders were subjected to extensive characterization. Compositional analysis of the powders indicated a crosslinked structure of the hydrogels with sufficient thermal stability to withstand spray drying. The obtained microparticles presented a spherical shape with mean diameter particle sizes from 2.3 ± 1.1 to 3.2 ± 2.9 μm. Microparticles formed from HA crosslinked with GA exhibited a reasonable aerosolization performance (fine particle fraction estimated as 28 ± 2%), whereas lower values were obtained for the UR-based formulation. Likewise, swelling and stability in water were larger for GA than for UR, for which the results were very similar to those obtained for native (not crosslinked) HA. In conclusion, microparticles could successfully be produced from crosslinked HA, and the ones crosslinked by GA exhibited superior performance in terms of aerosolization and swelling.

Mannitol Polymorphs as Carrier in DPIs Formulations: Isolation Characterization and Performance

The search for best performing carriers for dry powder inhalers is getting a great deal of interest to overcome the limitations posed by lactose. The aerosolization of adhesive mixtures between a carrier and a micronized drug is strongly influenced by the carrier solid-state properties. This work aimed at crystallizing kinetically stable D-mannitol polymorphs and at investigating their aerosolization performance when used in adhesive mixtures with two model drugs (salbutamol sulphate, SS, and budesonide, BUD) using a median and median/high resistance inhaler. A further goal was to assess in vitro the cytocompatibility of the produced polymer-doped mannitol polymorphs toward two lung epithelial cell lines. Kinetically stable (up to 12 months under accelerate conditions) α, and δ mannitol forms were crystallized in the presence of 2% w/w PVA and 1% w/w PVP respectively. These solid phases were compared with the β form and lactose as references. The solid-state properties of crystallized mannitol significantly affected aerosolization behavior, with the δ form affording the worst fine particle fraction with both the hydrophilic (9.3 and 6.5%) and the lipophilic (19.6 and 32%) model drugs, while α and β forms behaved in the same manner (11–13% for SS; 53–58% for BUD) and better than lactose (8 and 13% for SS; 26 and 39% for BUD). Recrystallized mannitol, but also PVA and PVP, proved to be safe excipients toward lung cell lines. We concluded that, also for mannitol, the physicochemical properties stemming from different crystal structures represent a tool for modulating carrier-drug interaction and, in turn, aerosolization performance.

Repurposing Melt Degradation for the Evaluation of Mixed Amorphous-Crystalline Blends

Medicine regulators require the melting points for crystalline drugs, as they are a test for chemical and physical quality. Many drugs, especially salt-forms, suffer concomitant degradation during melting; thus, it would be useful to know if the endotherm associated with melt degradation may be used for characterising the crystallinity of a powder blend. Therefore, the aim of this study was to investigate whether melt-degradation transitions can detect amorphous content in a blend of crystalline and amorphous salbutamol sulphate. Salbutamol sulphate was rendered amorphous by freeze and spray-drying and blended with crystalline drug, forming standards with a range of amorphous content. Crystalline salbutamol sulphate was observed to have a melt-degradation onset of 198.2±0.2°C, while anhydrous amorphous salbutamol sulphate prepared by either method showed similar glass transition temperatures of 119.4±0.7°C combined. Without the energy barrier provided by the ordered crystal lattice, the degradation endotherm for amorphous salbutamol sulphate occurred 50°C below the melting point, with an onset of 143.6±0.2°C. The enthalpies for this degradation transition showed no significant difference between freeze- and spray-dried samples (p>0.05). Distinct from convention, partial integration of the crystalline melt-degradation endotherm was applied to the region 193–221°C which had no contribution from the degradation of amorphous salbutamol sulphate. The linear correlation of these partial areas with amorphous content, R²=0.994, yielded limits of detection and quantification of 0.13% and 0.44% respectively, independent of drying technique. Melt-degradation transitions may be re-purposed for the measurement of amorphous content in powder blends, and they have potential for evaluating disorder more generally.

Understanding Carrier Performance in Low-Dose Dry Powder Inhalation: An In Vitro-In Silico Approach

The use of physiologically based pharmacokinetic (PBPK) models to support drug product development has become increasingly popular. The in vitro characterization of the materials of the formulation provides valuable descriptors for the in silico prediction of the drug’s pharmacokinetic profile. Thus, the application of an in vitro–in silico framework can be decisive towards the prediction of the in vivo performance of a new medicine. By applying such an approach, this work aimed to derive mechanistic based insights into the potential impact of carrier particles and powder bulk properties on the in vivo performance of a lactose-based dry powder inhaler (DPI). For this, a PBPK model was developed using salbutamol sulphate (SS) as a model drug and the in vitro performance of its low-dose blends (2% w/w) with different types of lactose particles was investigated using different DPI types (capsule versus reservoir) at distinct airflows. Likewise, the influence of various carrier’s particle and bulk properties, device type and airflow were investigated in silico. Results showed that for the capsule-based device, low-dose blends of SS had a better performance, when smaller carrier particles (Dv_0.5 ≈ 50 μm) with about 10% of fines were used. This resulted in a better predicted bioavailability of the drug for all the tested airflows. For the reservoir type DPI, the mean particle size (Dv_0.5) was identified as the critical parameter impacting performance. Shear cell and air permeability or compressibility measurements, particle size distribution by pressure titration and the tensile strength of the selected lactose carrier powders were found useful to generate descriptors that could anticipate the potential in vivo performance of the tested DPI blends.

Orally-disintegrating Tablets in Fixed-dose Combination Containing Ambroxol Hydrochloride and Salbutamol Sulphate Prepared by Direct Compression: Formulation Design, Development and In Vitro Evaluation

Objectives

To design a formulation and develop ODTs of AMB hydrochloride and salbutamol sulphate in combination for the treatment of respiratory disorders and perform an in vitro evaluation using superdisintegrants in combination with a suitable binder and excipients. Direct compression was used to prepare the tablets.

Materials and Methods

In the present research work, different concentrations of SSG as a superdisintegrant were used to optimize the concentration of SSG in the formulation of ODTs. Different concentrations of MCC and PVP K-30 were also studied along with the optimized SSG concentration. The tablets were evaluated for hardness, friability, weight variation, wetting time, in vitro DT, and percentage drug content uniformity. The optimized formulation was further evaluated in an in vitro release study, and drug-excipient compatibility and accelerated stability study.

Results

The optimized concentration of SSG was found as 4% on the basis of the lowest DT. The 1% concentration of MCC was selected as the optimum binder concentration on the basis of the lowest DT. ODTs passed all the quality control tests viz., weight variation, hardness, friability, in vitro DT, drug content (%) and wetting time. The formulation satisfied the requirements of the FDA for rapid-dissolving tablets and allowed more than 85% drug to be released within 30 min. The fourier transform infrared spectroscopy study revealed that there was no interaction between the drug and excipients. The accelerated stability study shows that formulation is quite stable at normal temperature and humidity conditions as well as at extreme temperature conditions.

Conclusion

By adopting a systematic formulation approach, ODTs of AMB hydrochloride and salbutamol sulphate in fixed-dose combination can be formulated using superdisintegrants in combination with appropriate binder and excipients; this was found to be economical and industrially feasible.

Chronomodulated drug delivery system of salbutamol sulphate for the treatment of nocturnal asthma

A time dependent pulsed release system consisting of an effervescent core surrounded by consecutive layers of swelling and rupturable polymers was prepared and evaluated. The cores containing salbutamol sulphate as bioactive agent were prepared by direct compression method using different ratios of microcrystalline cellulose and effervescent agent and then coated sequentially with an inner swelling layer containing a hydrocolloid, hydroxypropylmethylcellulose E5 and an outer rupturable layer having Eudragit RL/RS (1:1). The effects of various processing and formulative parameters on the performance of system were studied. The rupture and dissolution tests were studied using the USP paddle method at 50 rpm in 0.1 N HCl and phosphate buffer pH 6.8. The lag time of the drug release decreased by increasing the inner swelling layer and increased by increasing the rupturing layer level. All the results obtained in the present study suggest that osmotic pumping effect was involved which eventually lead to the drug release.

The effect of alkylpolyglycoside surfactants on the crystallization of spray-dried salbutamol sulphate: a GravimetricNear-Infrared Spectroscopy Study

This study monitored the effect of a series of structurally related surfactants on the crystallization of amorphous salbutamol sulphate. Amorphous salbutamol sulphate was prepared by spray drying from a solution in water and in the presence of various alkylpolyglycosides (APGs) at different concentrations. The particles were then analyzed using isothermal microcalorimetry and water vapor sorption (Dynamic Vapour Sorption, DVS) analysis combined with near-infrared spectroscopy (DVS-NIR). Both isothermal microcalorimetry and DVS-NIR were able to detect the transition from the amorphous to the crystalline state. The presence of APG surfactants modified the shape of the crystallization peak obtained using isothermal microcalorimetry. The gravimetric study combined with NIR revealed that while the crystallization was similar for the particles with or without surfactant, there was a great difference in the release of water from the newly formed crystal. In the presence of some of the surfactants tested, salbutamol sulphate released the water much faster than in the absence of surfactant. These results helped to explain the differences found in the isothermal microcalorimeter data. Differences were observed in the shapes of the NIR water peaks related to water due to the presence of the surfactant. In conclusion, the use of DVS combined with NIR has helped to analyze and understand the effect of APGs on the crystallization of amorphous salbutamol sulphate.