Novel Formulations of the Antiviral Drug Favipiravir: Improving Permeability and Tabletability

Abstract

Recently, favipiravir, as a broad-spectrum antiviral drug, has gain more attention because it might be a candidate to remedy the coronavirus disease 2019 (COVID-19). To improve its poor permeability and tabletability, four multicomponent crystals of favipiravir (FPV) were prepared by a slow evaporation or liquidassisted grinding method, including three cocrystals (FPVtheophylline, 1:1; FPV-saccharin, 1:1; FPV-5-fluorouracil, 1:1) and one salt (FPV-piperazine, 2:1). All of the crystal structures were solved by single-crystal X-ray diffraction. Interestingly, FPVtheophylline has a crystal structure similar to that of FPV, leading to similar properties, such as solubility, permeability, and tabletability. Except for FPV-theophylline, all of the other multicomponent crystals exhibit an enhanced permeability and tabletability. Our studies provide a new insight in overcoming the shortcomings of the important antiviral drug FPV.

Rational Development of a Carrier-Free Dry Powder Inhalation Formulation for Respiratory Viral Infections via Quality by Design: A Drug-Drug Cocrystal of Favipiravir and Theophylline

“…However, a similar search for FAV as of 2021, the CSD reports no adduct forms as this molecule as a coformer. However, very recent report of a similar THP-FAV cocrystal has emerged [73] but we can offer a more detailed view of crystal packing consistent with the robustness of this phase under the range of formulation conditions described.…”

Entacapone Polymorphs: Crystal Structures, Dissolution, Permeability, and Stability

“…Compared with the commercial form-I, the above results demonstrate that the permeability of novel ETP form-II is superior to that of the marketed form-I. Permeability of the commercial form-I is lower than that of the other polymorphs, and this observation prompts further studies to enhance not just solubility/dissolution but also drug permeability/flux pass in pharmaceutical crystal forms. − …”

Solid-state ion-selective electrodes for the first potentiometric determination of the anti-COVID 19 drug Remdesivir in human plasma; A comparative study

“…Thus, both have low water solubility. In contrast, the ionic size, solubility and lipophilicity of Favipiravir (Log P = -0.49) [50] and Molnupiravir (Log P = -0.8) [51] compared to RDS ions is primarily responsible for the strong selectivity against these compounds as they are more water soluble and less lipophilic in addition to their low molecular weights. Also, inorganic cations as sodium and potassium did not interfere due to the variations in their ionic size, mobility, and permeability when compared to the RDS ions.…”