4 ms·

> This is a completely novel molecule that appears effective as an antiviral. This would a huge achievement for the field of drug design, and will hopefully lea

by est31 5y ago

> This is a completely novel molecule that appears effective as an antiviral. This would a huge achievement for the field of drug design, and will hopefully lead to all kinds of great medicine. According to the Pfizer press release [0] Paxlovid uses Ritonavir [1], which is a known HIV antiviral, originally patented in 1989. At the start of the covid pandemic, chinese scientists even tried Kaletra, a generic that combines Ritonavir with another HIV antiviral, and found it to not improve outcomes [2], but this might have been due to them not giving the drug early enough in the infection, but only to hospitalized patients, while Pfizer gave it to non-hospitalized patients with a risk of later hospitalization. [0]: https://investors.pfizer.com/investor-news/press-release-details/2021/Pfizers-Novel-COVID-19-Oral-Antiviral-Treatment-Candidate-Reduced-Risk-of-Hospitalization-or-Death-by-89-in-Interim-Analysis-of-Phase-23-EPIC-HR-Study/default.aspx https://investors.pfizer.com/investor-news/press-release-det... [1]: https://en.wikipedia.org/wiki/Ritonavir https://en.wikipedia.org/wiki/Ritonavir [2]: https://doi.org/10.1056/NEJMoa2001282 https://doi.org/10.1056/NEJMoa2001282

bvm 5y ago
It's a combo regimen that includes ritonavir and PF-07321332 which does not have a generic name yet. Both are protease inhibitors.
- est31 5y ago
  Oh thought that was some id name for ritonavir. Seems you are right: > PF-07321332 is designed to block the activity of the SARS-CoV-2-3CL protease, an enzyme that the coronavirus needs to replicate. Co-administration with a low dose of ritonavir helps slow the metabolism, or breakdown, of PF-07321332 in order for it to remain active in the body for longer periods of time at higher concentrations to help combat the virus. So the main job is done by PF-07321332 even, while ritonavir is only there to keep PF-07321332 a bit longer from being destroyed by the body.
lekanwang 5y ago
Yeah, as parent mentioned in another reply below, ritonavir is an antiviral, but has no effect on SARS-CoV-2 (https://pubmed.ncbi.nlm.nih.gov/34048671/ https://pubmed.ncbi.nlm.nih.gov/34048671/). Ritonavir is just used to inhibit CYP and therefore reducing clearance of the drug.

by est31 5y ago

bvm 5y ago

It's a combo regimen that includes ritonavir and PF-07321332 which does not have a generic name yet. Both are protease inhibitors.

est31 5y ago
Oh thought that was some id name for ritonavir. Seems you are right: > PF-07321332 is designed to block the activity of the SARS-CoV-2-3CL protease, an enzyme that the coronavirus needs to replicate. Co-administration with a low dose of ritonavir helps slow the metabolism, or breakdown, of PF-07321332 in order for it to remain active in the body for longer periods of time at higher concentrations to help combat the virus. So the main job is done by PF-07321332 even, while ritonavir is only there to keep PF-07321332 a bit longer from being destroyed by the body.

lekanwang 5y ago

Yeah, as parent mentioned in another reply below, ritonavir is an antiviral, but has no effect on SARS-CoV-2 (https://pubmed.ncbi.nlm.nih.gov/34048671/ https://pubmed.ncbi.nlm.nih.gov/34048671/). Ritonavir is just used to inhibit CYP and therefore reducing clearance of the drug.