Zanamivir Microneedle Patches for Treatment of Influenza

Cidofovir structure (credit: wikipedia)

Cidofovir structure (credit: wikipedia)

Unmet Need

Many current and emerging antiviral drugs have chemical characteristics that result in poor cell penetration, which limits their ability to reach their intended target. These therapeutics cannot be given orally and must be delivered at high concentrations resulting in safety/toxicity issues that limit their widespread use in acute and preventative care settings.


TSRL, Inc. is developing novel antiviral analogues of proven therapeutics against a broad range of viral infections. Our prelead candidates are prodrugs of cidofovir and closely related acyclic nucleoside phosphonate (ANP) analogues. They are engineered to be orally available with substantially increased cell-based potency against human cytomegalovirus (CMV), including ganciclovir resistant-types, as well as a broad range of adenovirus strains, herpes viruses, polyoma viruses and smallpox.

Our approach has the potential to result in three major product advantages over existing therapies:

  1. Development of ANP therapeutics for treatment of AdV, CMV and other DNA virus infections as an alternative to cidofovir, valganciclovir, acyclovir and other antivirals;
  2. Substantially lower toxicity to kidneys; and
  3. Optimized dosing regimen based on a robust understanding of the pharmacokinetic (PK) to pharmacodynamics (PD) relationship.

Research Status

We are in the process of identifying a lead-candidate from the current set of preleads based on maximal broad-spectrum in vivo efficacy and largest therapeutic index for clinical use. Some of the supported intellectual property from our portfolio appears in the table below.

Supported Intellectual PropertyApp/Patent No.Filing DateExpiration Date
Cidofovir Peptide Conjugates as Prodrugs75110517/1/20053/12/26
Phosphonyl Ester Conjugates as Prodrugs80632093/16/200910/13/25
Tyrosine-based Prodrugs of Antiviral Agents89403134/23/20115/27/31

Expanding Access and Treatment Options

Healthcare Impact


Potential Regulatory Benefits


Market Potential


[1] T. Kojaoghlanian, P. Flomenberg and M. Horwitz, "The impact of adenovirus infection on the immunocompromised host," Rev. Med. Virol., vol. 13, p. 155–171, 2003.
[2] R. Schreier, "Infections in the Immunocompromised Host," MedScape, 2015.