Candidate drugs against SARS-CoV-2 and COVID-19.

Outbreak and pandemic of coronavirus SARS-CoV-2 in 2019/2020 will challenge global health for the future. Because a vaccine against the virus will not be available in the near future, we herein try to offer a pharmacological strategy to combat the virus. There exists a number of candidate drugs that may inhibit infection with and replication of SARS-CoV-2. Such drugs comprise inhibitors of TMPRSS2 serine protease and inhibitors of angiotensin-converting enzyme 2 (ACE2). Blockade of ACE2, the host cell receptor for the S protein of SARS-CoV-2 and inhibition of TMPRSS2, which is required for S protein priming may prevent cell entry of SARS-CoV-2. Further, chloroquine and hydroxychloroquine, and off-label antiviral drugs, such as the nucleotide analogue remdesivir, HIV protease inhibitors lopinavir and ritonavir, broad-spectrum antiviral drugs arbidol and favipiravir as well as antiviral phytochemicals available to date may limit spread of SARS-CoV-2 and morbidity and mortality of COVID-19 pandemic.

Freeze drying of orally disintegrating tablets containing taste masked naproxen sodium granules in blisters.

Orally disintegrating tablets (ODTs) were freeze dried in blisters using the Lyostar® II SMART™ Freeze Dryer Technology. ODT formulations either without non-water soluble particles (placebo) or containing large fractions (717 mg) of taste-masked naproxen sodium (NaS) granules were freeze dried. The process data revealed differences between ODTs with and without embedded granules in the pressure rise curves as well as in the shelf (inlet) temperature adjustments during freeze-drying. Pressure rise curves of the placebo ODTs from eight hours process time showed no distinct temperature-dominated part, and the last optimization step of the shelf temperature to achieve -24.4 °C might be prone to errors. The final shelf temperature of ODTs containing granules was -23.3 °C. The detection of primary drying endpoints using SMART™ Technology or comparative pressure measurements was reliable for both ODT formulations, whereas the application of thermocouples resulted in premature endpoint indication. Product resistance of ODTs containing granules was generally elevated in comparison to ODTs without granules, but increased only slightly over the course of the drying process. In summary, the developed freeze-drying cycle was found applicable for production of elegant ODTs with incorporated taste masked NaS granules.

Taste masking of naproxen sodium granules by fluid-bed coating.

The taste of oral dosage forms is an important argument regarding patient's compliance and acceptability. For this reason, it is often necessary to mask an undesirable and unpleasant taste of an active pharmaceutical ingredient. The purpose of this study was to mask the taste of naproxen sodium by a new fluid-bed coating approach. Different compositions of coating suspensions were used to coat naproxen sodium granules. It was found that products with the addition of a plasticizer were not stable at 40 °C and tended to agglomerate. Subsequently, formulations without plasticizer were used and the ratio between water and Eudragit® E was varied. Increasing the fraction of water in the suspension from 3% to 14% reduced the effective release of naproxen sodium. An optimum ratio between naproxen sodium granules and Eudragit® E was found to be 1:1.576, where less naproxen sodium was released than the threshold bitter value and an appropriate taste masking for more than 5 min was guaranteed. Investigation of the particle size distribution revealed a d(10) of 138.35 ± 21.52 µm, a d(50 )= 256.40 ± 11.27 µm and a d(90 )= 500.85 ± 69.08 µm, which guarantees an acceptable mouthfeel for patients.

Formulation, preparation, and evaluation of novel orally disintegrating tablets containing taste-masked naproxen sodium granules and naratriptan hydrochloride.

The purpose of this study was to develop and manufacture novel freeze-dried orally disintegrating tablets (ODTs) for migraine therapy containing taste-masked naproxen sodium and naratriptan hydrochloride. The formulation was optimized based on freeze-drying of sucrose solutions with different binders (hydroxyethylstarch, sodium alginate, methylcellulose, and gelatin) and varying amounts of Eudragit® E-coated naproxen sodium granules. Excellent product performance of the ODTs in terms of hardness and disintegration time (<10 s) independent of the mass of particles embedded was found for the solution consisting of sucrose and hydroxyethylstarch. Poloxamer 188, menthol flavor, naratriptan hydrochloride, and taste-masked naproxen sodium granules corresponding to 200 mg of naproxen were then added, and the final batches of ODTs for migraine therapy were produced. The ODTs were fully characterized, and subsequently stored for 1 month at room temperature and at 40°C. The amount of free naproxen sodium after freeze-drying and storage was below the threshold bitterness value, and the coating remained intact. Additionally, the particle size distribution of taste-masked granules was preserved, and more than 90 % naproxen sodium was released after 30 min. Naratriptan hydrochloride was dissolved immediately after disintegration, hence facilitating buccal absorption of the active pharmaceutical ingredient.

Application of gas pycnometry for the density measurement of freeze-dried products.

Gas pycnometry is applied to determine the density of solid materials. The analysis of lyophilisates is particularly challenging because of their porous structure. In this study, the density of raw materials and freeze-dried products was determined using different pycnometric methodologies and gases [helium (He), nitrogen (N2 ), sulfur hexafluoride]. The number of purges was set to 60 independent of the gas used. Intact and ground lyophilisates were examined, and major differences were found between use of He and N2 . For example, the density of sucrose lyophilisates measured using He remained almost constant before (1.51 g/cm(3) ) and after (1.52 g/cm(3) ) grinding. In contrast, the density of a sucrose lyophilisate before grinding determined with N2 was 1.33 g/cm(3) . On the basis of µCT and scanning electron microscopy pictures, it appears likely that the majority of pores are interconnected, with only a small fraction of closed pores. Helium is able to penetrate deep into the freeze-dried matrix and is supposedly absorbed by the material. The N2 molecules were not able to penetrate closed pores; therefore, the skeletal density of an intact lyophilisate was determined. Reproducibility of the established method was verified, and freeze-dried orally disintegrating tablets of different compositions were analyzed.

Influence of non-water-soluble placebo pellets of different sizes on the characteristics of orally disintegrating tablets manufactured by freeze-drying.

The present study describes the development of an orally disintegrating tablet containing a non-water-soluble drug delivery system. A model system was applied to evaluate the effect of different-sized particles on tablet characteristics. Cellets were incorporated into tablets prepared by freeze-drying from a 100 mg/mL mannitol or sucrose solution. Particle size distributions were 200-355 µm for Cellets 200 (C200) and 500-710 µm for Cellets 500 (C500). An examination of the tablets revealed that the particles could not be sufficiently embedded in mannitol because of its crystalline nature. The tablet hardness was also inadequate. In contrast, the hardness of sucrose tablets was increased by the addition of Cellets 500. Therefore, the sucrose-based formulation was studied further. Binders [hydroxyethylstarch, sodium alginate, methylcellulose (MC), and gelatin] were added in different concentrations, and tablets were made either with or without placebo pellets. A positive effect of the Cellets on the hardness of tablets was identified. Furthermore, disintegration time could be clearly reduced by Cellets for tablets made from 100 mg/mL sucrose with addition of 10 mg/mL MC, 20 or 40 mg/mL gelatin. The freeze-dried tablet index revealed that the formulations of sucrose with 50 mg/mL hydroxyethylstarch or 20 mg/mL gelatin were particularly advantageous.