Looking for the interactions between omeprazole and amoxicillin in a disordered phase. An experimental and theoretical study

Drug-drug co-amorphous systems: An emerging formulation strategy for poorly water-soluble drugs

Overcoming the poor water solubility of small-molecule drugs is a major challenge in the development of clinical pharmaceuticals. Amorphization of crystalline drugs is a highly effective strategy to improve their aqueous solubility. However, amorphous drugs are thermodynamically unstable and likely to crystallize during manufacturing and storage. Recently, drug-drug co-amorphous systems have emerged as a novel strategy to not only enable enhanced dissolution and physical stability of the individual drugs within the system but also to provide a strategy for combination therapy of the same or different clinical indications. This review serves to highlight advances in the methods used to manufacture and characterize drug-drug co-amorphous systems, summarize drug-drug co-amorphous applications reported in recent decades, and provide an outlook on future possibilities and perspectives.

Role of Hydrogen Bonds in Formation of Co-amorphous Valsartan/Nicotinamide Compositions of High Solubility and Durability with Anti-hypertension and Anti-COVID-19 Potential

Physicochemical properties, in particular solubility and the associated bioavailability, are key factors in determining efficacy of poorly water-soluble drugs, which constitute 40% of new drugs in the market, and improving them is an important challenge for modern pharmacy. A recent strategy to achieve this goal is formation of stable co-amorphous solid dispersions with co-formers of low molecular weight. Here, the amorphization strategy was applied for low-soluble anti-hypertensive valsartan (VAL), an angiotensin II receptor blocker, and nicotinamide, which exhibits lung- and cardio-protective effects. Through interactions with the renin-angiotensin-aldosteron system, VAL may be used to treat both hypertension and the current pandemic coronavirus SARS-CoV-2 infection. Using mechanochemical and liquid- and solid-state approaches, solvated co-amorphous solid dispersions of VAL with nicotinamide were obtained. They were characterized by spectroscopic, thermal, and X-ray analyses. The density functional theory, quantum theory of atoms in molecules, and non-covalent interaction index calculations revealed the presence of two types of hydrogen bonds between VAL and NIC (i.e., N-H···O and O-H···O). One of them had a partially covalent character, which caused conformational changes in the flexible VAL molecule, restricting contribution of the tetrazolyl N-H donor and thus limiting the possibility of co-crystal formation. The recognized VAL/NIC1- and VAL/NIC2-type heterodimeric interactions were responsible for the excellent durability of the solid compositions and up to 24-fold better solubility than VAL alone. The synthesized dispersions constitute a new class of dually acting drugs, containing an active pharmaceutical ingredient (VAL) and supporting nutraceutical (nicotinamide).

Co-Amorphous Drug Formulations in Numbers: Recent Advances in Co-Amorphous Drug Formulations with Focus on Co-Formability, Molar Ratio, Preparation Methods, Physical Stability, In Vitro and In Vivo Performance, and New Formulation Strategies

Co-amorphous drug delivery systems (CAMS) are characterized by the combination of two or more (initially crystalline) low molecular weight components that form a homogeneous single-phase amorphous system. Over the past decades, CAMS have been widely investigated as a promising approach to address the challenge of low water solubility of many active pharmaceutical ingredients. Most of the studies on CAMS were performed on a case-by-case basis, and only a few systematic studies are available. A quantitative analysis of the literature on CAMS under certain aspects highlights not only which aspects have been of great interest, but also which future developments are necessary to expand this research field. This review provides a comprehensive updated overview on the current published work on CAMS using a quantitative approach, focusing on three critical quality attributes of CAMS, i.e., co-formability, physical stability, and dissolution performance. Specifically, co-formability, molar ratio of drug and co-former, preparation methods, physical stability, and in vitro and in vivo performance were covered. For each aspect, a quantitative assessment on the current status was performed, allowing both recent advances and remaining research gaps to be identified. Furthermore, novel research aspects such as the design of ternary CAMS are discussed.

Insights into co-amorphous systems in therapeutic drug delivery

Co-amorphous (CAM) systems are promising drug-delivery systems in the arena of therapeutic drug delivery, addressing the poor aqueous solubility of drugs by enhancing solubility and thereby improving the oral bioavailability and therapeutic effect of the drug. A CAM system is a single-phase homogeneous blend of two or more low molecular weight molecules that can be drug–drug or drug–co-former, stabilized via intermolecular interactions, adding the benefit of thermodynamic stability. This review covers the fundamentals of CAM systems and recent advances in formulation development. In particular, we strive to address the theoretical, molecular, technical and biopharmaceutical aspects, advantages over polymeric amorphous solid dispersions, mechanisms of stabilization of amorphous forms, insights into unexplored in silico tools in excipient selection and regulatory viewpoints.

Dual-drug amorphous formulation of gliclazide

Amorphization is a well-established strategy to enhance the dissolution properties of poorly water-soluble drugs. However, the amorphous state is inherently unstable toward recrystallization. Coamorphous systems of a drug and a small-molecule excipient or of two complementary drugs often show an enhanced stability. Diabetes and hypertension are frequently coexistent. In this paper a study on the coamorphization of the poorly water-soluble antidiabetic drug gliclazide (glz) and the antihypertensive drug valsartan (val) is reported. Amorphous glz recrystallized after 1 d under ambient conditions, whereas coamorphous glz-val containing glz and val in a 1:1 or 1:2 molar ratio was stable for at least four months at 20 °C and 56% relative humidity. The dissolution rate of glz increased in the order crystalline glz < glz-val_1:1 < glz-val_1:2. Furthermore, ternary coamorphous systems of glz, val and an excipient were prepared; glz-val_1:1_PVP, glz-val_1:1_HPC, glz-val_1:1_ALM, glz-val_1:1_MCC (PVP = polyvinylpyrrolidone, HPC = hydroxypropyl cellulose, ALM = α-lactose monohydrate, MCC = microcrystalline cellulose). MCC and HPC did not affect the stability of the coamorphous system, while ALM promoted the recrystallization of glz in glz-val_1:1_ALM during storage and freshly prepared glz-val_1:1_PVP contained small amounts of crystalline glz. Glz-val_1:1_MCC showed enhanced dissolution properties compared to crystalline glz and glz-val_1:1 and is a viable fixed-dose formulation.

Modeling polypharmacy side effects with graph convolutional networks

Motivation

The use of drug combinations, termed polypharmacy, is common to treat patients with complex diseases or co-existing conditions. However, a major consequence of polypharmacy is a much higher risk of adverse side effects for the patient. Polypharmacy side effects emerge because of drug-drug interactions, in which activity of one drug may change, favorably or unfavorably, if taken with another drug. The knowledge of drug interactions is often limited because these complex relationships are rare, and are usually not observed in relatively small clinical testing. Discovering polypharmacy side effects thus remains an important challenge with significant implications for patient mortality and morbidity.

Results

Here, we present Decagon, an approach for modeling polypharmacy side effects. The approach constructs a multimodal graph of protein-protein interactions, drug-protein target interactions and the polypharmacy side effects, which are represented as drug-drug interactions, where each side effect is an edge of a different type. Decagon is developed specifically to handle such multimodal graphs with a large number of edge types. Our approach develops a new graph convolutional neural network for multirelational link prediction in multimodal networks. Unlike approaches limited to predicting simple drug-drug interaction values, Decagon can predict the exact side effect, if any, through which a given drug combination manifests clinically. Decagon accurately predicts polypharmacy side effects, outperforming baselines by up to 69%. We find that it automatically learns representations of side effects indicative of co-occurrence of polypharmacy in patients. Furthermore, Decagon models particularly well polypharmacy side effects that have a strong molecular basis, while on predominantly non-molecular side effects, it achieves good performance because of effective sharing of model parameters across edge types. Decagon opens up opportunities to use large pharmacogenomic and patient population data to flag and prioritize polypharmacy side effects for follow-up analysis via formal pharmacological studies.

Availability and implementation

Source code and preprocessed datasets are at: http://snap.stanford.edu/decagon.

Co-Amorphous Solid Dispersions for Solubility and Absorption Improvement of Drugs: Composition, Preparation, Characterization and Formulations for Oral Delivery

The amorphous solid state offers an improved apparent solubility and dissolution rate. However, due to thermodynamic instability and recrystallization tendencies during processing, storage and dissolution, their potential application is limited. For this reason, the production of amorphous drugs with adequate stability remains a major challenge and formulation strategies based on solid molecular dispersions are being exploited. Co-amorphous systems are a new formulation approach where the amorphous drug is stabilized through strong intermolecular interactions by a low molecular co-former. This review covers several topics applicable to co-amorphous drug delivery systems. In particular, it describes recent advances in the co-amorphous composition, preparation and solid-state characterization, as well as improvements of dissolution performance and absorption are detailed. Examples of drug-drug, drug-carboxylic acid and drug-amino acid co-amorphous dispersions interacting via hydrogen bonding, π−π interactions and ionic forces, are presented together with corresponding final dosage forms.