EIDD-2801 (Molnupiravir)

  • Molecular formula: C13H19N3O7
  • CAS# 2349386-89-4
  • Molecular weight: 329.31
  • [(2R,3S,4R,5R)-3,4-dihydroxy-5-[4-(hydroxyamino)-2-oxopyrimidin-1-yl]oxolan-2-yl]methyl 2-methylpropanoate
  • Synonymum: MK-4482
  • EIDD-1931 prodrug
  • Patent# WO-2019173602-A1
  • ChemSrc, PubChem

EIDD-2801 is being investigated for its activity against many viral infections, including influenza, MERS-CoV and SARS-CoV-2.

Mechanism of action

EIDD-2801 is the isopropylester prodrug of [N4-hydroxycytidine]. With improved oral bioavailability in non human primates, it is hydrolyzed in vivo, and distributes into tissues where it becomes the active 5’-triphosphate form. The active drug incorporates into the genome of RNA viruses, leading to an accumulation of mutations known as viral error catastrophe. Recent studies have shown EIDD-2801 inhibits replication of human and bat coronaviruses, including SARS-CoV-2, in mice and human airway epithelial cells. A [remdesivir] resistant mutant mouse hepatitis virus has also been shown to have increased sensitivity to N4-hydroxycytidine.

Please note that the information mentioned below does not come from officially published results of clinical trials. This is information from one of the drug manufacturers.

EIDD-2801 testing in the treatment of FIP

At the end of 2020, testing of Molnupiravir for the treatment of FIP began.
A study entitled "Oral nutrition treatment effects on the survival time and quality of life for feline infectious peritonitis" included 286 cats diagnosed with FIP from around the world. Several animal clinics in the United States, the United Kingdom, Italy, Germany, France, Japan, Romania, Turkey, and China participated in this study. Due to ethical factors, no placebo control group was formed. The results of this study are: Of the 286 cases, no deaths occurred. 28/286 cases were cured after 4-6 weeks of treatment. 258/286 cases were cured after 8 weeks of treatment. 28/286 cases received this medicine at a dose of 30-40 mg / kg every 24 hours, of which 26 cases recovered after 4 weeks, including 2 cases with eye disease and 5 cases with neurological symptoms, while another 2 cases discontinued treatment after 6 weeks of treatment without relapse. At the time of publication of the results, all cats were still alive and without signs of disease 3-5 months after the end of treatment.

Dosage and duration of treatment

  • Dry/Wet FIP: 25mg/kg
  • Ocular FIP: 37,5mg/kg
  • Neurological FIP: 50mg/kg

Duration of treatment 5-10 weeks depending on the severity of the disease and the particular cat.
The price has not been determined yet.

Additional information

According to the available information, tablets containing EIDD-2801 from two known manufacturers of GS-441524 should appear on the market in the short term (~ 9-10 / 2021).

In the Czech Republic, one cat finished treatment with EIDD-2801 (end of treatment of wet FIP 24.7.2021 - we hope for a smooth posttreatment course). In the Slovak Republic there is a cat with a third relapse of neurological FIP after treatment with GS441524. Treatment of this relapse is performed with the concomitant use of GS441524 and EIDD-2801.