Lumefantrine co-amorphous systems using deoxycholic acid as a co-former: NIR at-line process monitoring by machine learning.

Multi-method coamorphous systems of lumefantrine with alpha ketoglutaric acid: Comprehensive characterization, biological evaluation and stability analysis.

Introduction Strategies to address the problem of poorly water-soluble drugs encompass the conversion of a crystalline drug into an amorphous form to promote its apparent solubility and dissolution. Co-amorphous systems (CAMs) incorporate low molecular mass molecules (co-formers), which are mixed with the drug to form one single phase [1,2]. The aim of this study is to understand the capability of different co-formers (amino, carboxylic and sulphonic acids), in the production of CAMs with olanzapine by ball milling, solvent evaporation and quench cooling. Materials and methods Mixtures (2 g) of olanzapine (OLZ) and each co-former [l-aspartate (ASP); l-tryptophan (TRY); l-arginine (ARG); l-proline (PRO); citric acid (CIT); tartaric acid (TAR); oxalic acid (OXA); saccharine (SAC); potassium acessulfame (ACE); cyclamic acid (CYC)] in 1:1 molar ratios were submitted to ball milling (BM), solvent evaporation (SE) and quench cooling (QC). CAMs were evaluated for the OLZ solubility increase, co-formability and storage stability over time, by differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD) and Fourier-transform infra-red spectroscopy (FTIR). Results The BM technique presented the most promising results followed by QC and SE (Table 1), since more CAMs were produced. All the sulphonic acids (SAC, CYC and ACE) formed CAMs regardless of the technique used, presenting complete amorphization probably due to their higher ability to produce intermolecular interactions, like hydrogen-bonding, thus increasing the stability of CAMs (more than 8 weeks at 25 °C/11 and 53% RH). Conversely, amino acids were the least efficient in producing CAMs. Crystalline OLZ presented low solubility (40.1 mg/L) in water and a general increase in the solubility of the CAMs was observed. Carboxylic acids (TAR, CIT, OXA) achieved the biggest increase (up to 269 times, BM with TART) followed by sulphonic acids (up to 199 times, SE with SAC), unveiling the possibility of improved dissolution profiles and bioavailability. Discussion and conclusions: The study has shown the possibility of converting a crystalline drug into an amorphous entity, particularly when in presence of co-formers which stabilise the amorphous structures formed. In fact, with sulphonic acids, both SE and BM, achieved complete amorphization and successfully stabilised the CAMs obtained. Due to the noteworthy increase in solubility, resulting from co-amorphization, this technique is considered to be adequate to process active compounds with poor water solubility, such as OLZ. Table 1. Comparison of the of co-amorphization ability using different techniques and co-formers. Mixtures QC SE BM OLZ:PRO Yesa No No OLZ:ARG No No No OLZ:TRY No No Yesa OLZ:SER No No No OLZ:ASP No No Yesa OLZ:CIT Yesa No Yesb OLZ:TAR Yesa No Yesb OLZ:OXA Yesa No No OLZ:SAC Yesb Yesb Yesb OLZ:CYC No Yesb Yesb OLZ:ACE Yesb Yesb Yesb aIncomplete amorphization; bcomplete amorphization.

Coamorphous Active Pharmaceutical Ingredient–Small Molecule Mixtures: Considerations in the Choice of Coformers for Enhancing Dissolution and Oral Bioavailability

Coamorphous systems using citric acid as a small molecular excipient were studied for improving physical stability and bioavailability of loratadine, a BCS class II drug with low water solubility and high permeability. Coamorphous loratadine-citric acid systems were prepared by solvent evaporation technique and characterized by differential scanning calorimetry, X-ray powder diffraction, and Fourier transform infrared spectroscopy. Solid-state analysis proofed that coamorphous loratadine-citric acid system (1:1) was amorphous and homogeneous, had a higher T g over amorphous loratadine, and the intermolecular hydrogen bond interactions between loratadine and citric acid exist. The solubility and dissolution of coamorphous loratadine-citric acid system (1:1) were found to be significantly greater than those of crystalline and amorphous form. The pharmacokinetic study in rats proved that coamorphous loratadine-citric acid system (1:1) could significantly improve absorption and bioavailability of loratadine. Coamorphous loratadine-citric acid system (1:1) showed excellently physical stability over a period of 3months at 25°C under 0% RH and 25°C under 60% RH conditions. The improved stability of coamorphous loratadine-citric acid system (1:1) could be related to an elevated T g over amorphous form and the intermolecular hydrogen bond interactions between loratadine and citric acid. These studies demonstrate that the developed coamorphous loratadine-citric acid system might be a promising oral formulation for improving solubility and bioavailability of loratadine.

Sinomenine-phenolic acid coamorphous drug systems: Solubilization, sustained release, and improved physical stability

Sulfonic Acid Derivatives in the Production of Stable Co-Amorphous Systems for Solubility Enhancement

Tranilast-matrine co-amorphous system: Strong intermolecular interactions, improved solubility, and physiochemical stability

Indomethacin co-amorphous drug-drug systems with improved solubility, supersaturation, dissolution rate and physical stability

Coamorphization of a poorly water-soluble active pharmaceutical ingredient (API) has been proven to be effective in improving its solubility. Generally, API can form multiple coamorphous systems with different coformers. However, it remains unclear how the pKa value of different coformers influences the solubility of the API. In this study, structurally related cinnamic acid (CA, pKa = 4.37) and p-hydroxycinnamic acid (pHCA, pKa = 4.65) were chosen as coformers for the coamorphization of lurasidone hydrochloride (LH). To investigate the influence of the pKa value of the coformers on the solubility of LH, LH-CA/pHCA coamorphous systems were prepared by the vacuum rotary evaporation method and characterized by powder X-ray diffraction and differential scanning calorimetry. Fourier-transform infrared spectroscopy, Raman spectroscopy, and molecular dynamics (MD) simulations were employed to investigate the intermolecular interaction of the coamorphous systems. It was found that the solubility of LH in the coamorphous LH–pHAC with a higher-pKa coformer was higher than that of the coamorphous LH-CA. In addition, according to the solubility product principle-based formula derivation, we established the functional relationship between the solubility of LH and the pKa of the coformers at different-pH buffering solution. It was found that the coformer with a larger pKa value would be more beneficial to improve the solubility profile of LH. Collectively, the current study offers an effective strategy to improve the poor solubility of drugs by increasing the pKa value of the coformer in coamorphous systems.

Structure and energetics of intermolecular association in two lurasidone co-amorphous drug systems

Two coamorphous drug-amino acid systems, indomethacin-tryptophan (Ind-Trp) and furosemide-tryptophan (Fur-Trp), were analyzed toward their ease of amorphization and mechanism of coamorphization during ball milling. The two mixtures were compared to the corresponding amorphization of the pure drug without amino acid. Powder blends at a 1:1 molar ratio were milled for varying times, and their physicochemical properties were investigated using XRPD, (13)C solid state NMR (ssNMR), and DSC. Comilling the drug with the amino acid reduced the milling time required to obtain an amorphous powder from more than 90 min in the case of the pure drugs to 30 min for the coamorphous powders. Amorphization was observed as reductions in XRPD reflections and was additionally quantified based on normalized principal component analysis (PCA) scores of the ssNMR spectra. Furthermore, the evolution in the glass temperature (Tg) of the coamorphous systems over time indicated complete coamorphization after 30 min of milling. Based on the DSC data it was possible to identify the formation mechanism of the two coamorphous systems. The Tg position of the samples suggested that coamorphous Ind-Trp was formed by the amino acid being dissolved in the amorphous drug, whereas coamorphous Fur-Trp was formed by the drug being dissolved in the amorphous amino acid.

The use of co-amorphous systems containing a combination of low molecular weight drugs and excipients is a relatively new technology in the pharmaceutical field to improve the solubility of poorly water-soluble drugs. However, some co-amorphous systems show a lower glass transition temperature ( Tg) than many of their polymeric solid dispersion counterparts. In this study, we aimed at designing a stable co-amorphous system with an elevated Tg. Carbamazepine (CBM) and citric acid (CA) were employed as the model drug and the coformer, respectively. co-amorphous CBM-CA at a 1:1 molar ratio was formed by ball milling, but a transition from the glassy to the supercooled melt state was observed under ambient conditions, due to the relatively low Tg of 38.8 °C of the co-amorphous system and moisture absorption. To improve the Tg of the coformer, salt formation of a combination of l-arginine (ARG) with CA was studied. First, ball milling of CA-ARG at molar ratios of 1:1, 1:2, and 1:3 forming co-amorphous systems was performed and led to a dramatic enhancement of the Tg, depending on the CA-ARG ratio. Salt formation between CA and ARG was observed by infrared spectroscopy. Next, ball milling of CBM-CA-ARG at molar ratios of 1:1:1, 1:1:2, and 1:1:3 resulted in co-amorphous blends, which had a single Tg at 77.8, 105.3, and 127.8 °C, respectively. These ternary co-amorphous samples remained in a solid amorphous form for 2 months at 40 °C. From these results, it can be concluded that blending of the salt coformer with a drug is a promising strategy to design stable co-amorphous formulations.

Background/Objectives: Tuberculosis (TB) remains a global health challenge due to long treatment durations, poor adherence, and growing drug resistance. Inhalable co-amorphous systems (COAMS) offer a promising strategy for targeted pulmonary delivery of fixed-dose combinations, improving efficacy and reducing systemic side effects. Methods: Our in-house-developed machine learning (ML) tool identified two promising API-API combinations for TB therapy, rifampicin (RIF)–moxifloxacin (MOX) and RIF–ethambutol (ETH). Physiologically based pharmacokinetic (PBPK) modeling was used to estimate therapeutic lung doses of RIF, ETH, and MOX following oral administration. Predicted lung doses were translated into molar ratios, and COAMS of RIF-ETH and RIF-MOX at both model-predicted (1:1) and PBPK-informed ratios were prepared by spray drying and co-milling, followed by comprehensive physicochemical and aerodynamic characterization. Results: RIF-MOX COAMS could be prepared in all molar ratios tested, whereas RIF-ETH failed to result in COAMS for therapeutically relevant molar ratios. Spray drying and ball milling successfully produced stable RIF-MOX formulations, with spray drying showing superior behavior in terms of morphology (narrow particle size distribution; lower Sauter mean diameter), aerosolization performance (fine particle fraction above 74% for RIF and MOX), and dissolution. Conclusions: This study demonstrated that PBPK modeling and ML are useful tools to develop COAMS for pulmonary delivery of active pharmaceutical ingredients (APIs) routinely applied through the oral route. It was also observed that COAMS may be less effective when the therapeutic lung dose ratio significantly deviates from the predicted 1:1 molar ratio. This suggests the need for alternative delivery strategies in such cases.

Co-crystals and co-amorphous systems are two strategies to improve the physical properties of an active pharmaceutical ingredient and, thus, have recently gained considerable interest both in academia and the pharmaceutical industry. In this study, the behavior of the recently identified sodium naproxen-lactose-tetrahydrate co-crystal and the co-amorphous mixture of sodium, naproxen, and lactose was investigated. The structure of the co-crystal is described using single-crystal X-ray diffraction. The structural analysis revealed a monoclinic lattice, space group P21, with the asymmetric unit containing one molecule of lactose, one of naproxen, sodium, and four water molecules. Upon heating, it was observed that the co-crystal transforms into a co-amorphous system due to the loss of its crystalline bound water. Dehydration and co-amorphization were studied using synchrotron X-ray radiation and thermogravimetric analysis (TGA). Subsequently, different processing techniques (ball milling, spray drying, and dehydration) were used to prepare the co-amorphous mixture of sodium, naproxen, and lactose. X-ray powder diffraction (XRPD) revealed the amorphous nature of the mixtures after preparation. Differential scanning calorimetry (DSC) analysis showed that the blends were single-phase co-amorphous systems as indicated by a single glass transition temperature. The samples were subsequently tested for physical stability under dry (silica gel at 25 and 40 °C) and humid conditions (25 °C/75% RH). The co-amorphous samples stored at 25 °C/75% RH quickly recrystallized into the co-crystalline state. On the other hand, the samples stored under dry conditions remained physically stable after five months of storage, except the ball milled sample stored at 40 °C which showed signs of recrystallization. Under these dry conditions, however, the ball-milled co-amorphous blend crystallized into the individual crystalline components.

The potential of supramolecular synthon to develop coamorphous systems with tailored physical stability: Mechanistic insights integrating kinetics and thermodynamics