Cyclodextrins in Antiviral Therapeutics and Vaccines

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The review of Braga et al. describes the various roles of cyclodextrins (CDs) in vaccines against
viruses and in antiviral therapeutics [1]. The first section describes the most commonly studied application of cyclodextrins—solubilisation and stabilisation of antiviral drugs; some examples also
refer to their beneficial taste-masking activity. The second part of the review describes the role
of cyclodextrins in antiviral vaccine development and stabilisation, where they are employed as
adjuvants and cryopreserving agents. In addition, cyclodextrin-based polymers as delivery systems
for mRNA are currently under development. Lastly, the use of cyclodextrins as pharmaceutical
active ingredients for the treatment of viral infections is explored. This new field of application is still
taking its first steps. Nevertheless, promising results from the use of cyclodextrins as agents to treat
other pathologies are encouraging.

We can learn that the recently approved vaccine of Janssen (ad26.cov2.s) contains HPβCD in the formulation as a cryopreservative, that is, to avoid cold-induced damage to the surface of the viral particles.

Pharmaceutics 13 00409 g006 550
Schematic representation of the interactions between adenovirus particles (orange) and HPβCD molecules (blue) in the ad26.cov2.s vaccine. Cyclodextrin molecules are used in large excess and claimed to act as cryopreservatives, helping to stabilise the surface of the virus during the freeze-drying step of the vaccine preparation.

In human vaccines, HPβCD is the best choice for adjuvanticity because it is already approved by the regulating entities and it has an excellent safety profile. Moreover, HPβCD is able to induce lymphocyte proliferation, especially the T-helper type 2 (Th2) cells. These cells, also known as CD4+ cells, are an important part of the immunisation effect of vaccines, contributing to maintaining a longer immune response. HPβCD is more advantageous than aluminium salts, which are currently the most commonly employed adjuvants. Unlike aluminium, HPβCD induces little immunoglobulin E (IgE) production, thus reducing the allergenic risk of the vaccine.

[1] Braga, S.S.; Barbosa, J.S.; Santos, N.E.; El-Saleh, F.; Paz, F.A.A. Cyclodextrins in Antiviral Therapeutics and Vaccines. Pharmaceutics 2021, 13, 409. https://doi.org/10.3390/pharmaceutics13030409

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