Physicochemical Study of Ribavirin Complexes with α-, β- and γ-Cyclodextrins

Cyclodextrins in the antiviral therapy

The main antiviral drug-cyclodextrin interactions, changes in physicochemical and physiological properties of the most commonly used virucides are summarized. The potential complexation of antiviral molecules against the SARS-Cov2 also pointed out the lack of detailed information in designing effective and general medicines against viral infections. The principal problem of the current molecules is the 3D structures of the currently active compounds. Improving the solubility or bioavailability of antiviral molecules is possible, however, there is no universal solution, and the complexation experiments dominantly use the already approved cyclodextrin derivatives. This review discusses the basic properties of the different cyclodextrin derivatives, their potential in antiviral formulations, and the prevention and treatment of viral infections. The biologically active new cyclodextrin derivatives are also discussed.

In vivo nose-to-brain delivery of the hydrophilic antiviral ribavirin by microparticle agglomerates

Nasal administration has been proposed as a potential approach for the delivery of drugs to the central nervous system. Ribavirin (RBV), an antiviral drug potentially useful to treat viral infections both in humans and animals, has been previously demonstrated to attain several brain compartments after nasal administration. Here, a powder formulation in the form of agglomerates comprising micronized RBV and spray-dried microparticles containing excipients with potential absorption enhancing properties, i.e. mannitol, chitosan, and α-cyclodextrin, was developed for nasal insufflation. The agglomerates were characterized for particle size, agglomeration yield, and ex vivo RBV permeation across rabbit nasal mucosa as well as delivery from an animal dry powder insufflator device. Interestingly, permeation enhancers such as chitosan and mannitol showed a lower amount of RBV permeating across the excised nasal tissue, whereas α-cyclodextrin proved to outperform the other formulations and to match the highly soluble micronized RBV powder taken as a reference. In vivo nasal administration to rats of the agglomerates containing α-cyclodextrin showed an overall higher accumulation of RBV in all the brain compartments analyzed as compared with the micronized RBV administered as such without excipient microparticles. Hence, powder agglomerates are a valuable approach to obtain a nasal formulation potentially attaining nose-to-brain delivery of drugs with minimal processing of the APIs and improvement of the technological and biopharmaceutical properties of micronized API and excipients, as they combine optimal flow properties for handling and dosing, suitable particle size for nasal deposition, high surface area for drug dissolution, and penetration enhancing properties from excipients such as cyclodextrins.

4'-Hydroxy-6,7-methylenedioxy-3-methoxyflavone: A novel flavonoid from Dulacia egleri with potential inhibitory activity against cathepsins B and L

A new flavone, 4'-hydroxy-6,7-methylenedioxy-3-methoxyflavone 1, and two other nucleosides, ribavirin 2 and adenosine 3, were isolated from the leaves of Dulacia egleri. The nucleosides were identified by spectroscopic techniques (1D, 2D-NMR) while the structure of the flavonoid was established by 1D, 2D-NMR analysis, including HRESIMS data. The results obtained in the biological assays showed that the compound 1 was able to inhibit cathepsins B and L with IC₅₀ of 14.88 ± 0.18 μM and 3.19 ± 0.07 μM, respectively. The mechanism of inhibition for both enzymes were determined showing to be competitive at cathepsin B with Ki = 12.8 ± 0.6 μM and non-linear non-competitive with positive cooperativity inhibition at cathepsin L with K_i = 322 ± 33 μM, αK_i = 133 ± 15 μM, βK_i = 5.14 ± 0.41 μM and γK_i = 13.2 ± 13 μM.

Evaluation by Q-RTPCR of the efficacy of ribavirin complexed with beta-cyclodextrin against measles virus in a mouse encephalitis model

The objective of this work was to study the antiviral activity of ribavirin on measles encephalitis infection when using cyclodextrins as carriers. The use of cyclic oligosaccharides can promote the activity of many drugs and the benefit of the association of ribavirin with beta-cyclodextrin has already been demonstrated in vitro. Intracranial inoculation of the rodent adapted neurovirulent CAM/RB strain of measles virus induces encephalitis in CBA/ca mice. The antiviral activity of the complex ribavirin/beta-cyclodextrin at molar ratio 1:1 has been evaluated in vivo in the above encephalitis model. CBA/ca mice were treated with daily intraperitoneal injection of ribavirin (40 mg/kg) with or without beta-cyclodextrin. The viral load in the brain of mice was quantified by real-time Reverse transcription-Polymerase chain reaction. Treatment of mice by the complex ribavirin/beta-cyclodextrin (1:1) by intraperitoneal route decreases the viral load in the brain of 1.1 and 0.7 log(10) Eq copies x mL(-1) compared to distillated water and ribavirin treatment, respectively. At the same time, free ribavirin injection shows a negligible difference compared to treatment by distillated water.