Active pharmaceutical ingredients (API) with unfavorable physicochemical properties and stability present a significant challenge during their processing into final dosage forms. Cocrystallization of such APIs with suitable coformers is an efficient approach to mitigate the solubility and stability concerns. A considerable number of cocrystal-based products are currently being marketed and show an upward trend. However, to improve the API properties by cocrystallization, coformer selection plays a paramount role. Selection of suitable coformers not only improves the drug’s physicochemical properties but also improves the therapeutic effectiveness and reduces side effects. Numerous coformers have been used till date to prepare pharmaceutically acceptable cocrystals. The carboxylic acid-based coformers, such as fumaric acid, oxalic acid, succinic acid, and citric acid, are the most commonly used coformers in the currently marketed cocrystal-based products. Carboxylic acid-based coformers are capable of forming the hydrogen bond and contain smaller carbon chain with the APIs. This review summarizes the role of coformers in improving the physicochemical and pharmaceutical properties of APIs, and deeply explains the utility of afore-mentioned coformers in API cocrystal formation. The review concludes with a brief discussion on the patentability and regulatory issues related to pharmaceutical cocrystals.

Stability is an essential quality attribute of any pharmaceutical formulation. Poor stability can change the color and physical appearance of a drug, directly impacting the patient’s perception. Unstable drug products may also face loss of active pharmaceutical ingredients (APIs) and degradation, making the medicine ineffective and toxic. Moisture content is known to be the leading cause of the degradation of nearly 50% of medicinal products, leading to impurities in solid dose formulations. The polarity of the atoms in an API and the surface chemistry of API particles majorly influence the affinity towards water molecules. Moisture induces chemical reactions, including free water that has also been identified as an important factor in determining drug product stability. Among the various approaches, crystal engineering and specifically co-crystals, have a proven ability to increase the stability of moisture-sensitive APIs. Other approaches, such as changing the salt form, can lead to solubility issues, thus making the co-crystal approach more suited to enhancing hygroscopic stability. There are many reported studies where co-crystals have exhibited reduced hygroscopicity compared to pure API, thereby improving the product’s stability. In this review, the authors focus on recent updates and trends in these studies related to improving the hygroscopic stability of compounds, discuss the reasons behind the enhanced stability, and briefly discuss the screening of co-formers for moisture-sensitive drugs.

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: Coronaviruses are a group of known RNA virus which primarily infects the respiratory tract, and also neurological, enteric, and hepatic systems. Endemic outbreaks of Middle East Coronavirus Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) have been observed in recent decades. A new strain named the SARS CoV-2(COVID-19) virus has now spread across the globe. SARS-CoV-2 is highly communicable and has culminated in a massive pandemic of COVID-19. Currently, no successful treatment is available. Therefore, an urgent need is there for new screening models that can aid in identifying the drugs with potential activity against COVID-19. The current review aims to discuss various in-silico, in-vitro and in-vivo screening methods, that can potentially be used to expedite the discovery of new active therapeutic candidates and vaccines, drug targets, and repurposing the commercially available drugs against COVID-19 for the effective management of the infection and thereby controlling this pandemic. Further, the current status of drugs and vaccines under clinical investigation has been summarized.