Phase Diagrams of Polymer-Dispersed Liquid Crystal Systems of Itraconazole/Component Immiscibility Induced by Molecular Anisotropy

The Influence of PVP Polymer Topology on the Liquid Crystalline Order of Itraconazole in Binary Systems

This study presents a novel approach by utilizing poly(vinylpyrrolidone)s (PVPs) with various topologies as potential matrices for the liquid crystalline (LC) active pharmaceutical ingredient itraconazole (ITZ). We examined amorphous solid dispersions (ASDs) composed of ITZ and (i) self-synthesized linear PVP, (ii) self-synthesized star-shaped PVP, and (iii) commercial linear PVP K30. Differential scanning calorimetry, X-ray diffraction, and broad-band dielectric spectroscopy were employed to get a comprehensive insight into the thermal and structural properties, as well as global and local molecular dynamics of ITZ-PVP systems. The primary objective was to assess the influence of PVPs' topology and the composition of ASD on the LC ordering, changes in the temperature of transitions between mesophases, the rate of their restoration, and finally the solubility of ITZ in the prepared ASDs. Our research clearly showed that regardless of the PVP type, both LC transitions, from smectic (Sm) to nematic (N) and from N to isotropic (I) phases, are effectively suppressed. Moreover, a significant difference in the miscibility of different PVPs with the investigated API was found. This phenomenon also affected the solubility of API, which was the greatest, up to 100 μg/mL in the case of starPVP 85:15 w/w mixture in comparison to neat crystalline API (5 μg/mL). Obtained data emphasize the crucial role of the polymer's topology in designing new pharmaceutical formulations.

Characterization of Drug with Good Glass-Forming Ability Loaded Mesoporous Silica Nanoparticles and Its Impact Toward in vitro and in vivo Studies

Solid oral dosage forms are mostly preferred in pharmaceutical formulation development due to patient convenience, ease of product handling, high throughput, low manufacturing costs, with good physical and chemical stability. However, 70% of drug candidates have poor water solubility leading to compromised bioavailability. This phenomenon occurs because drug molecules are often absorbed after dissolving in gastrointestinal fluid. To address this limitation, delivery systems designed to improve the pharmacokinetics of drug molecules are needed to allow controlled release and target-specific delivery. Among various strategies, amorphous formulations show significantly high potential, particularly for molecules with solubility-limited dissolution rates. The ease of drug molecules to amorphized is known as their glass-forming ability (GFA). Specifically, drug molecules categorized into class III based on the Taylor classification have a low recrystallization tendency and high GFA after cooling, with substantial "glass stability" when heated. In the last decades, the application of mesoporous silica nanoparticles (MSNs) as drug delivery systems (DDS) has gained significant attention in various investigations and the pharmaceutical industry. This is attributed to the unique physicochemical properties of MSNs, including high loading capacity, recrystallization inhibition, excellent biocompatibility, and easy functionalization. Therefore, this study aimed to discuss the current state of good glass former drug loaded mesoporous silica and shows its impact on the pharmaceutical properties including dissolution and physical stability, along with in vivo study. The results show the importance of determining whether mesoporous structures are needed in amorphous formulations to improve the pharmaceutical properties of drug with a favorable GFA.

The Impact of Various Poly(vinylpyrrolidone) Polymers on the Crystallization Process of Metronidazole

In this paper, we propose one-step synthetic strategies for obtaining well-defined linear and star-shaped polyvinylpyrrolidone (linPVP and starPVP). The produced macromolecules and a commercial PVP K30 with linear topology were investigated as potential matrices for suppressing metronidazole (MTZ) crystallization. Interestingly, during the formation of binary mixtures (BMs) containing different polymers and MTZ, we found that linear PVPs exhibit maximum miscibility with the drug at a 50:50 weight ratio (w/w), while the star-shaped polymer mixes with MTZ even at a 30:70 w/w. To explain these observations, comprehensive studies of MTZ-PVP formulations with various contents of both components were performed using Fourier-transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction. The obtained results clearly showed that the polymer's topology plays a significant role in the type of interactions occurring between the matrix and MTZ. Additionally, we established that for MTZ-PVP 50:50 and 75:25 w/w BMs, linear polymers have the most substantial impact on inhibiting the crystallization of API. The star-shaped macromolecule turned out to be the least effective in stabilizing amorphous MTZ at these polymer concentrations. Nevertheless, long-term structural investigations of the MTZ-starPVP 30:70 w/w system (which is not achievable for linear PVPs) demonstrated its complete amorphousness for over one month.

Glass Microneedles: A Case Study for Regulatory Approval Using a Quality by Design Approach

In this paper, a roadmap is provided for the regulatory approval of one of the exciting and dynamic drug delivery fields, microneedles, by using a Quality by Design approach to pharmaceutical product development. In this regard, a quality target product profile (QTPP) and the critical quality attributes (CQA) of microneedles are identified. A case study of the recently patented method of fabricating glass microneedles entirely from a therapeutic agent, thus eliminating the requirement for additional excipients is discussed. The glass microneedle, ArrayPatch, is a propriety wearable device with platform potential consisting of an array of sharp, but painless, dissolvable microneedles manufactured with 100% drug. The microneedles penetrate the skin on application and dissolve to deliver a locally effective dose. The in vitro characterization of the microneedle CQAs under WHO-guided stability conditions will be described to assess the manufacturing readiness of ArrayPatch.  A live technical video is also provided, presenting a unique procedure of jugular vein cannulation through the ear vein of a pig animal model to study the in vivo pharmacokinetics of ArrayPatch compared to standard-of-care marketed products.

Effect of Shear Strain on the Supercooled Itraconazole

This article investigated the effect of shear strain on the nematic itraconazole (ITR) from both elastic and plastic deformation regions. The rheo-dielectric technique was used for this purpose. It has been demonstrated that shear strain can change the sample color, liquid crystal alignment as well as its dielectric and thermal properties. The observed modifications depend on the shear strain value. One can distinguish four regions regarding the slope of ITR stress-strain dependence and caused changes. Proper alignment changes (obtained after the shearing procedure) can additionally affect the further recrystallization of ITR to other than the initial, i.e., second polymorphic form.

Can amphotericin B and itraconazole be co-delivered orally? Tailoring oral fixed-dose combination coated granules for systemic mycoses

The incidence and prevalence of invasive fungal infections have increased significantly over the last few years, leading to a global health problem due to the lack of effective treatments. Amphotericin B (AmB) and itraconazole (ITR) are two antifungal drugs with different mechanisms of action. In this work, AmB and ITR have been formulated within granules to elicit an enhanced pharmacological effect, while enhancing the oral bioavailability of AmB. A Quality by Design (QbD) approach was utilised to prepare fixed-dose combination (FDC) granules consisting of a core containing AmB with functional excipients, such as inulin, microcrystalline cellulose (MCC), chitosan, sodium deoxycholate (NaDC) and Soluplus® and polyvinyl pyrrolidone (PVP), coated with a polymeric layer containing ITR with Soluplus® or a combination of Poloxamer 188 and hydroxypropyl methyl cellulose-acetyl succinate (HPMCAS). A Taguchi design of experiments (DoE) with 7 factors and 2 levels was carried out to understand the key factors impacting on the physicochemical properties of the formulation followed by a Box-Behnken design with 3 factors in 3 levels chosen to optimise the formulation parameters. The core of the FDC granules was obtained by wet granulation and later coated using a fluidized bed. In vitro antifungal efficacy was demonstrated by measuring the inhibition halo against different species of Candida spp., including C. albicans (24.19-30.48 mm), C. parapsilosis (26.38-27.84 mm) and C. krusei (11.48-17.92 mm). AmB release was prolonged from 3 to 24 h when the AmB granules were coated. In vivo in CD-1 male mice studies showed that these granules were more selective towards liver, spleen and lung compared to kidney (up to 5-fold more selective in liver, with an accumulation of 8.07 µg AmB/g liver after twice-daily 5 days administration of granules coated with soluplus-ITR), resulting in an excellent oral administration option in the treatment of invasive mycosis. Nevertheless, some biochemical alterations were found, including a decrease in blood urea nitrogen (∼17 g/dl) and alanine aminotransferase (<30 U/l) and an increase in the levels of bilirubin (∼0.2 mg/dl) and alkaline phosphatase (<80 U/l), which could be indicative of a liver failure. Once-daily regimen for 10 days can be a promising therapy.

The impact of the size of acetylated cyclodextrin on the stability of amorphous metronidazole

Modified oligosaccharides with cyclic topology seem to be promising excipients for the preparation of Amorphous Solid Dispersions (ASDs), especially with those Active Pharmaceutical Ingredients (APIs), which have a strong crystallization tendency from the amorphous/glassy state. Herein, the usefulness of two acetylated cyclodextrins (ac-α-CD and ac-β-CD) with various molecular weights (M_w) as stabilizers for the supercooled metronidazole (Met) has been discussed. X-ray diffraction (XRD) studies carried out on Met-acCDs mixtures (prepared in molar ratios from 1:2 to 5:1) showed that the system with ac-α-CD containing the highest amount of API (5:1 m/m) crystallizes immediately after preparation, whereas all Met-ac-β-CD ASDs remain stable. What is more, long-term XRD measurements confirmed that the Met-ac-α-CD 2:1 m/m system crystallizes after 100 days of storage in contrast to the same system containing ac-β-CD. The non-isothermal calorimetric data revealed that the activation barrier for crystallization (E_cr) in ASDs with the oligosaccharide having a greater M_w (i.e., composed of seven acGLU molecules) is slightly higher. Finally, to explain the differences in behavior between the mixtures with both acCDs, infrared studies, DFT calculations and Molecular Dynamics simulations were performed. All methods excluded the scenario of API incorporation inside the acCDs' core. On the other hand, obtained results suggested that in comparison to ac-α-CD, the greater amount of Met molecules might be bounded on the outside surface of ac-β-CD. Therefore, this modified saccharide is a better stabilizer of the examined API.

Factors Influencing the Crystallization-Onset Time of Metastable ASDs

In formulation development, amorphous solid dispersions (ASD) are considered to improve the bioavailability of poorly water-soluble active pharmaceutical ingredients (APIs). However, the crystallization of APIs often limits long-term stability and thus the shelf life of ASDs. It has already been shown earlier that the long-term stability of ASDs strongly depends on the storage conditions (relative humidity, temperature), the manufacturing methods, and the resulting particle sizes. In this work, ASDs composed of the model APIs Griseofulvin (GRI) or Itraconazole (ITR) and the polymers poly (vinylpyrrolidone-co-vinyl acetate) (PVPVA) or Soluplus® were manufactured via spray drying and hot-melt extrusion. Each API/polymer combination was manufactured using the two manufacturing methods with at least two different API loads and two particle-size distributions. It was a priori known that these ASDs were metastable and would crystallize over time, even in the dry stage. The amount of water absorbed by the ASD from humid air (40 °C/75% relative humidity), the solubility of the API in the ASD at humid conditions, and the resulting glass-transition temperature were predicted using the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) and the Gordon–Taylor approach, respectively. The onset of crystallization was determined via periodic powder X-ray diffraction (PXRD) measurements. It was shown that simple heuristics such as “larger particles always crystallize later than smaller particles” are correct within one manufacturing method but cannot be transferred from one manufacturing method to another. Moreover, amorphous phase separation in the ASDs was shown to also influence their crystallization kinetics. Counterintuitively, phase separation accelerated the crystallization time, which could be explained by the glass-transition temperatures of the evolving phases.

Encapsulation of drug into mesoporous silica by solvent evaporation: A comparative study of drug characterization in mesoporous silica with various molecular weights

Mesoporous silica (MS) is a promising material as a drug carrier that is used in pharmaceutical applications. It was discovered that the incorporation of drugs into MS has the potential to improve their dissolution and bioavailability due to the large specific surface area. This study aimed to characterize the drugs with various molecular weights in MS as well as to elucidate their impact on the loading amount and the amorphization within MS. The solvent evaporation method was used to encapsulate itraconazole (ITZ), nifedipine (NIF), and nicotinamide (NIC), respectively, into MS. The result shows the absence of glass transition and the melting peak of ITZ, NIF, and SAC within MS signifying the successful encapsulation. A hallo pattern was found in ITZ and NIF within MS indicating the amorphization. The high molecular weight and the interaction between the drug with the silica surface is reportedly contributed to the formation of the amorphous state. Meanwhile, the characteristic diffraction peaks of NIC crystal were observed for NIC within MS. In conclusion, the molecular weight of the drug has a significant effect on the loading amount and the amorphization of the drug within MS.

High-Pressure Dielectric Studies-a Way to Experimentally Determine the Solubility of a Drug in the Polymer Matrix at Low Temperatures

In this work, we employed broad-band dielectric spectroscopy to determine the solubility limits of nimesulide in the Kollidon VA64 matrix at ambient and elevated pressure conditions. Our studies confirmed that the solubility of the drug in the polymer matrix decreases with increasing pressure, and molecular dynamics controls the process of recrystallization of the excess of amorphous nimesulide from the supersaturated drug–polymer solution. More precisely, recrystallization initiated at a certain structural relaxation time of the sample stops when a molecular mobility different from the initial one is reached, regardless of the temperature and pressure conditions. Finally, based on the presented results, one can conclude that by transposing vertically the results obtained at elevated pressures, one can obtain the solubility limit values corresponding to low temperatures. This approach was validated by the comparison of the experimentally determined points with the theoretically obtained values based on the Flory–Huggins theory.

Role of Polymer Excipients in the Kinetic Stabilization of Drug-Rich Nanoparticles

Amorphous solid dispersions (ASDs) of crystallizable drugs and polymer excipients are attractive for enhancing the solubility and bioavailability of hydrophobic drug molecules. In this study, the solution behavior of poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) (PND) and poly(vinylpyrrolidone-co-vinylacetate) (PVPVA), as polymer excipients, and nilutamide (NLT), phenytoin (PHY), and itraconazole (ITN) as model drugs, were monitored by an in vitro dissolution assay, small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), and polarized optical microscopy (POM). High degrees of drug supersaturation were coincident with the formation of amorphous nanoparticles in each system. The difference in particle size and kinetic stability between PND and PVPVA systems suggest a difference in how the polymers interact with the drug-rich phase. A series of scenarios are proposed based on whether the polymer interacts more strongly with the drug-rich nanoparticles or with water. Understanding the contribution of drug-rich nanoparticles to achievable supersaturation and the effect of polymer excipients on these particles will inform the design of future solid dispersion systems through a better understanding of the polymer/drug solution relationship.

Isochronal Conditions-The Key To Maintain the Given Solubility Limit, of a Small Molecule within the Polymer Matrix, at Elevated Pressure

In this work, we proposed the method to maintain the desired level of drug's solubility within the polymer matrix by adjusting conditions to uphold the same molecular dynamics of the system (e.g., temperature for set elevated pressure or vice versa). Namely, we observed, that recrystallization of the drug from the supersaturated drug-polymer system, initiated for the same structural relaxation time of the sample (τα-1) ceases when certain, different than the initial, molecular mobility of the systems is reached (τα-2)-regardless of a given combination of temperature and pressure conditions. Based on the presented results, one can conclude that the molecular dynamics seem to control the process of recrystallization of the excess amount of solute from the supersaturated solution (e.g., small molecules dissolved within the polymer). Therefore, it appears that the elevated pressure compensates the effect of solubility enhancement caused by the elevated temperature. Such information not only is of fundamental relevance in science but also, from a much broader perspective, could be potentially very useful considering extrusion-based manufacturing methods.

Identification and Pharmaceutical Characterization of a New Itraconazole Terephthalic Acid Cocrystal

The crystallization of poorly soluble drug molecules with an excipient into new solid phases called cocrystals has gained a considerable popularity in the pharmaceutical field. In this work, the cocrystal approach was explored for a very poorly water soluble antifungal active, itraconazole (ITR), which was, for the first time, successfully converted into this multicomponent solid using an aromatic coformer, terephthalic acid (TER). The new cocrystal was characterized in terms of its solid-state and structural properties, and a panel of pharmaceutical tests including wettability and dissolution were performed. Evidence of the cocrystal formation was obtained from liquid-assisted grinding, but not neat grinding. An efficient method of the ITR–TER cocrystal formation was ball milling. The stoichiometry of the ITR–TER phase was 2:1 and the structure was stabilized by H-bonds. When comparing ITR–TER with other cocrystals, the intrinsic dissolution rates and powder dissolution profiles correlated with the aqueous solubility of the coformers. The rank order of the dissolution rates of the active pharmaceutical ingredient (API) from the cocrystals was ITR–oxalic acid > ITR–succinic acid > ITR–TER. Additionally, the ITR–TER cocrystal was stable in aqueous conditions and did not transform to the parent drug. In summary, this work presents another cocrystal of ITR that might be of use in pharmaceutical formulations.

Utility of Films to Anticipate Effect of Drug Load and Polymer on Dissolution Performance from Tablets of Amorphous Itraconazole Spray-Dried Dispersions

Because spray-dried dispersion (SDD) performance depends on polymer selection and drug load, time- and resource-sparing methods to screen drug/polymer combinations before spray drying are desirable. The primary objective was to assess the utility of films to anticipate the effects of drug load and polymer grade on dissolution performance of tablets containing SDDs of itraconazole (ITZ). A secondary objective was to characterize the solid-state attributes of films and SDDs to explain drug load and polymer effects on dissolution performance. SDDs employed three different grades of hypromellose acetate succinate (i.e., either HPMCAS-L, HPMCAS-M, or HPMCAS-H). Solid-state characterization employed differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and solid-state nuclear magnetic resonance (ssNMR) spectroscopy. Results indicate that films correctly anticipated the effects of drug load and polymer on dissolution performance. The best dissolution profiles were observed under the following conditions: 20% drug loading performed better than 30% for both films and SDDs, and the polymer grade rank order was HPMCAS-L > HPMCAS-M > HPMCAS-H for both films and SDDs. No dissolution was detected from films or SDDs containing HPMCAS-H. Solid-state characterization revealed percent crystallinity and phase miscibility as contributing factors to dissolution, but were not the sole factors. Amorphous content in films varied with drug load (10% > 20% > 30%) and polymer grades (HPMCAS-L > HPMCAS-M > HPMCAS-H), in agreement with dissolution. In conclusion, films anticipated the rank-order effects of drug load and polymer grade on dissolution performance from SDDs of ITZ, in part through percent crystallinity and phase miscibility influences.

How does the high pressure affects the solubility of the drug within the polymer matrix in solid dispersion systems

In this paper, we employed Broadband Dielectric Spectroscopy (BDS) in order to determine the effect of the high pressure on the solubility limits of the amorphous flutamide within Kollidon VA64 matrix. In order to achieve this goal, drug-polymer systems have been examined: (i) at ambient pressure and both isothermal and nonisothermal conditions by means of BDS as well as Differential Scanning Calorimetry (DSC), to validate proposed method; (ii) at high pressure conditions (20 and 50 MPa) and elevated temperatures (343 K, 353 K and 363 K) by means of dielectric spectroscopy. Our studies revealed that regardless of applied pressure the solubility of the flutamide within the co-polymer matrix increases with increasing temperature at isobar conditions. Moreover, our results clearly indicate that with increasing pressure the solubility of the drug within the polymer matrix is decreasing at isothermal conditions. Therefore, during the solubility limit studies one should consider the situation in which by increasing the pressure (at constant temperature) would achieve an effect similar to the lowering of the temperature (at constant pressure).